diff --git a/tests/ActiveDataProviderTest.php b/tests/ActiveDataProviderTest.php
index 4d4579641..44efed6e7 100644
--- a/tests/ActiveDataProviderTest.php
+++ b/tests/ActiveDataProviderTest.php
@@ -3,9 +3,9 @@
 namespace yiiunit\extensions\mongodb;
 
 use MongoDB\BSON\ObjectID;
+use yii;
 use yii\data\ActiveDataProvider;
 use yii\mongodb\Query;
-use yiiunit\extensions\mongodb\data\ar\ActiveRecord;
 use yiiunit\extensions\mongodb\data\ar\Customer;
 
 class ActiveDataProviderTest extends TestCase
@@ -13,8 +13,6 @@ class ActiveDataProviderTest extends TestCase
     protected function setUp()
     {
         parent::setUp();
-        $this->mockApplication();
-        ActiveRecord::$db = $this->getConnection();
         $this->setUpTestRows();
     }
 
@@ -29,7 +27,7 @@ protected function tearDown()
      */
     protected function setUpTestRows()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = Yii::$app->mongodb->getCollection('customer');
         $rows = [];
         for ($i = 1; $i <= 10; $i++) {
             $rows[] = [
@@ -51,14 +49,12 @@ public function testQuery()
 
         $provider = new ActiveDataProvider([
             'query' => $query,
-            'db' => $this->getConnection(),
         ]);
         $models = $provider->getModels();
         $this->assertEquals(10, count($models));
 
         $provider = new ActiveDataProvider([
             'query' => $query,
-            'db' => $this->getConnection(),
             'pagination' => [
                 'pageSize' => 5,
             ]
diff --git a/tests/ActiveFixtureTest.php b/tests/ActiveFixtureTest.php
index b7b58bd74..19d9a0dee 100644
--- a/tests/ActiveFixtureTest.php
+++ b/tests/ActiveFixtureTest.php
@@ -10,11 +10,6 @@
 
 class ActiveFixtureTest extends TestCase
 {
-    protected function setUp()
-    {
-        parent::setUp();
-        $this->mockApplication();
-    }
 
     protected function tearDown()
     {
@@ -32,7 +27,7 @@ public function testLoadCollection()
         $fixture = $this->getMockBuilder(ActiveFixture::className())
             ->setConstructorArgs([
                 [
-                    'db' => $this->getConnection(),
+                    'db' => Yii::$app->mongodb,
                     'collectionName' => Customer::collectionName()
                 ]
             ])
@@ -45,7 +40,7 @@ public function testLoadCollection()
 
         $fixture->load();
 
-        $rows = $this->findAll($this->getConnection()->getCollection(Customer::collectionName()));
+        $rows = $this->findAll(Yii::$app->mongodb->getCollection(Customer::collectionName()));
         $this->assertCount(2, $rows);
     }
 
@@ -55,7 +50,7 @@ public function testLoadClass()
         $fixture = $this->getMockBuilder(ActiveFixture::className())
             ->setConstructorArgs([
                 [
-                    'db' => $this->getConnection(),
+                    'db' => yii::$app->mongodb,
                     'collectionName' => Customer::collectionName()
                 ]
             ])
@@ -68,7 +63,7 @@ public function testLoadClass()
 
         $fixture->load();
 
-        $rows = $this->findAll($this->getConnection()->getCollection(Customer::collectionName()));
+        $rows = $this->findAll(yii::$app->mongodb->getCollection(Customer::collectionName()));
         $this->assertCount(2, $rows);
     }
 
@@ -83,7 +78,7 @@ public function testLoadEmptyData()
         $fixture = $this->getMockBuilder(ActiveFixture::className())
             ->setConstructorArgs([
                 [
-                    'db' => $this->getConnection(),
+                    'db' => Yii::$app->mongodb,
                     'collectionName' => Customer::collectionName()
                 ]
             ])
@@ -95,7 +90,7 @@ public function testLoadEmptyData()
 
         $fixture->load(); // should be no error
 
-        $rows = $this->findAll($this->getConnection()->getCollection(Customer::collectionName()));
+        $rows = $this->findAll(Yii::$app->mongodb->getCollection(Customer::collectionName()));
         $this->assertEmpty($rows);
     }
 
@@ -106,7 +101,6 @@ public function testLoadEmptyData()
      */
     public function testDefaultDataFile()
     {
-        $db = $this->getConnection();
 
         $fixturePath = Yii::getAlias('@runtime/fixtures');
         $fixtureDataPath = $fixturePath . DIRECTORY_SEPARATOR . 'data';
@@ -138,29 +132,27 @@ class {$className} extends \yii\mongodb\ActiveFixture
             ['name' => 'name2'],
             ['name' => 'name3'],
         ];
-        $fixtureDataFile = $fixtureDataPath . DIRECTORY_SEPARATOR . $db->getDefaultDatabaseName() . '.' . Customer::collectionName() . '.php';
+        $fixtureDataFile = $fixtureDataPath . DIRECTORY_SEPARATOR . Yii::$app->mongodb->getDefaultDatabaseName() . '.' . Customer::collectionName() . '.php';
         $fixtureDataContent = '<?php return ' . VarDumper::export($fixtureData) . ';';
         file_put_contents($fixtureDataFile, $fixtureDataContent);
 
         /* @var $fixture ActiveFixture */
 
         $fixture = new $className([
-            'db' => $db,
             'collectionName' => Customer::collectionName(),
         ]);
         $fixture->load();
-        $rows = $this->findAll($this->getConnection()->getCollection(Customer::collectionName()));
+        $rows = $this->findAll(Yii::$app->mongodb->getCollection(Customer::collectionName()));
         $this->assertCount(2, $rows);
 
         $fixture = new $className([
-            'db' => $db,
             'collectionName' => [
-                $db->getDefaultDatabaseName(),
+                Yii::$app->mongodb->getDefaultDatabaseName(),
                 Customer::collectionName()
             ],
         ]);
         $fixture->load();
-        $rows = $this->findAll($this->getConnection()->getCollection(Customer::collectionName()));
+        $rows = $this->findAll(yii::$app->mongodb->getCollection(Customer::collectionName()));
         $this->assertCount(3, $rows);
     }
-}
\ No newline at end of file
+}
diff --git a/tests/ActiveRecordTest.php b/tests/ActiveRecordTest.php
index 7c259d6ed..d99d551cb 100644
--- a/tests/ActiveRecordTest.php
+++ b/tests/ActiveRecordTest.php
@@ -5,8 +5,8 @@
 use MongoDB\BSON\Binary;
 use MongoDB\BSON\ObjectID;
 use MongoDB\BSON\Regex;
+use yii;
 use yii\mongodb\ActiveQuery;
-use yiiunit\extensions\mongodb\data\ar\ActiveRecord;
 use yiiunit\extensions\mongodb\data\ar\Customer;
 use yiiunit\extensions\mongodb\data\ar\Animal;
 use yiiunit\extensions\mongodb\data\ar\Dog;
@@ -22,7 +22,6 @@ class ActiveRecordTest extends TestCase
     protected function setUp()
     {
         parent::setUp();
-        ActiveRecord::$db = $this->getConnection();
         $this->setUpTestRows();
     }
 
@@ -37,7 +36,7 @@ protected function tearDown()
      */
     protected function setUpTestRows()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $rows = [];
         for ($i = 1; $i <= 10; $i++) {
             $rows[] = [
@@ -282,44 +281,42 @@ public function testExists()
 
     public function testScalar()
     {
-        $connection = $this->getConnection();
 
         $result = Customer::find()
             ->select(['name' => true, '_id' => false])
             ->orderBy(['name' => SORT_ASC])
             ->limit(1)
-            ->scalar($connection);
+            ->scalar();
         $this->assertSame('name1', $result);
 
         $result = Customer::find()
             ->select(['name' => true, '_id' => false])
             ->andWhere(['status' => -1])
-            ->scalar($connection);
+            ->scalar();
         $this->assertSame(false, $result);
 
         $result = Customer::find()
             ->select(['name'])
             ->orderBy(['name' => SORT_ASC])
             ->limit(1)
-            ->scalar($connection);
+            ->scalar();
         $this->assertSame('name1', $result);
 
         $result = Customer::find()
             ->select(['_id'])
             ->limit(1)
-            ->scalar($connection);
+            ->scalar();
         $this->assertTrue($result instanceof ObjectID);
     }
 
     public function testColumn()
     {
-        $connection = $this->getConnection();
 
         $result = Customer::find()
             ->select(['name' => true, '_id' => false])
             ->orderBy(['name' => SORT_ASC])
             ->limit(2)
-            ->column($connection);
+            ->column();
         $this->assertEquals(['name1', 'name10'], $result);
 
         $result = Customer::find()
@@ -327,21 +324,21 @@ public function testColumn()
             ->andWhere(['status' => -1])
             ->orderBy(['name' => SORT_ASC])
             ->limit(2)
-            ->column($connection);
+            ->column();
         $this->assertEquals([], $result);
 
         $result = Customer::find()
             ->select(['name'])
             ->orderBy(['name' => SORT_ASC])
             ->limit(2)
-            ->column($connection);
+            ->column();
         $this->assertEquals(['name1', 'name10'], $result);
 
         $result = Customer::find()
             ->select(['_id'])
             ->orderBy(['name' => SORT_ASC])
             ->limit(2)
-            ->column($connection);
+            ->column();
         $this->assertTrue($result[0] instanceof ObjectID);
         $this->assertTrue($result[1] instanceof ObjectID);
     }
diff --git a/tests/ActiveRelationTest.php b/tests/ActiveRelationTest.php
index 0f2cd9748..b0ebe9c5e 100644
--- a/tests/ActiveRelationTest.php
+++ b/tests/ActiveRelationTest.php
@@ -2,7 +2,7 @@
 
 namespace yiiunit\extensions\mongodb;
 
-use yiiunit\extensions\mongodb\data\ar\ActiveRecord;
+use yii;
 use yiiunit\extensions\mongodb\data\ar\Customer;
 use yiiunit\extensions\mongodb\data\ar\CustomerOrder;
 use yiiunit\extensions\mongodb\data\ar\Item;
@@ -12,7 +12,6 @@ class ActiveRelationTest extends TestCase
     protected function setUp()
     {
         parent::setUp();
-        ActiveRecord::$db = $this->getConnection();
         $this->setUpTestRows();
     }
 
@@ -38,7 +37,7 @@ protected function setUpTestRows()
                 'status' => $i,
             ];
         }
-        $customerCollection = $this->getConnection()->getCollection('customer');
+        $customerCollection = yii::$app->mongodb->getCollection('customer');
         $customers = $customerCollection->batchInsert($customers);
 
         $items = [];
@@ -48,7 +47,7 @@ protected function setUpTestRows()
                 'price' => $i,
             ];
         }
-        $itemCollection = $this->getConnection()->getCollection('item');
+        $itemCollection = yii::$app->mongodb->getCollection('item');
         $items = $itemCollection->batchInsert($items);
 
         $customerOrders = [];
@@ -70,7 +69,7 @@ protected function setUpTestRows()
                 ],
             ];
         }
-        $customerOrderCollection = $this->getConnection()->getCollection('customer_order');
+        $customerOrderCollection = yii::$app->mongodb->getCollection('customer_order');
         $customerOrderCollection->batchInsert($customerOrders);
     }
 
diff --git a/tests/BatchQueryResultTest.php b/tests/BatchQueryResultTest.php
index af04a3813..d47134eba 100644
--- a/tests/BatchQueryResultTest.php
+++ b/tests/BatchQueryResultTest.php
@@ -2,9 +2,9 @@
 
 namespace yiiunit\extensions\mongodb;
 
+use yii;
 use yii\mongodb\BatchQueryResult;
 use yii\mongodb\Query;
-use yiiunit\extensions\mongodb\data\ar\ActiveRecord;
 use yiiunit\extensions\mongodb\data\ar\Customer;
 use yiiunit\extensions\mongodb\data\ar\CustomerOrder;
 
@@ -13,7 +13,6 @@ class BatchQueryResultTest extends TestCase
     protected function setUp()
     {
         parent::setUp();
-        ActiveRecord::$db = $this->getConnection();
         $this->setUpTestRows();
     }
 
@@ -38,7 +37,7 @@ protected function setUpTestRows()
                 'status' => $i,
             ];
         }
-        $customerCollection = $this->getConnection()->getCollection('customer');
+        $customerCollection = yii::$app->mongodb->getCollection('customer');
         $customers = $customerCollection->batchInsert($customers);
 
         $customerOrders = [];
@@ -52,7 +51,7 @@ protected function setUpTestRows()
                 'number' => $customer['status'] + 100,
             ];
         }
-        $customerOrderCollection = $this->getConnection()->getCollection('customer_order');
+        $customerOrderCollection = yii::$app->mongodb->getCollection('customer_order');
         $customerOrderCollection->batchInsert($customerOrders);
     }
 
@@ -60,12 +59,11 @@ protected function setUpTestRows()
 
     public function testQuery()
     {
-        $db = $this->getConnection();
 
         // initialize property test
         $query = new Query();
         $query->from('customer')->orderBy('id');
-        $result = $query->batch(2, $db);
+        $result = $query->batch(2);
         $this->assertTrue($result instanceof BatchQueryResult);
         $this->assertEquals(2, $result->batchSize);
         $this->assertTrue($result->query === $query);
@@ -74,7 +72,7 @@ public function testQuery()
         $query = new Query();
         $query->from('customer');
         $allRows = [];
-        $batch = $query->batch(2, $db);
+        $batch = $query->batch(2);
         foreach ($batch as $rows) {
             $allRows = array_merge($allRows, $rows);
         }
@@ -84,7 +82,7 @@ public function testQuery()
         $query = new Query();
         $query->from('customer')->orderBy('name');
         $allRows = [];
-        $batch = $query->batch(2, $db);
+        $batch = $query->batch(2);
         foreach ($batch as $rows) {
             $allRows = array_merge($allRows, $rows);
         }
@@ -106,7 +104,7 @@ public function testQuery()
         $query = new Query();
         $query->from('customer')->where(['name' => 'unexistingName']);
         $allRows = [];
-        $batch = $query->batch(2, $db);
+        $batch = $query->batch(2);
         foreach ($batch as $rows) {
             $allRows = array_merge($allRows, $rows);
         }
@@ -116,7 +114,7 @@ public function testQuery()
         $query = new Query();
         $query->from('customer')->indexBy('name');
         $allRows = [];
-        foreach ($query->batch(2, $db) as $rows) {
+        foreach ($query->batch(2) as $rows) {
             $allRows = array_merge($allRows, $rows);
         }
         $this->assertEquals(9, count($allRows));
@@ -128,7 +126,7 @@ public function testQuery()
         $query = new Query();
         $query->from('customer')->orderBy('name');
         $allRows = [];
-        foreach ($query->each(100, $db) as $rows) {
+        foreach ($query->each(100) as $rows) {
             $allRows[] = $rows;
         }
         $this->assertEquals(9, count($allRows));
@@ -140,7 +138,7 @@ public function testQuery()
         $query = new Query();
         $query->from('customer')->orderBy('name')->indexBy('name');
         $allRows = [];
-        foreach ($query->each(100, $db) as $key => $row) {
+        foreach ($query->each(100) as $key => $row) {
             $allRows[$key] = $row;
         }
         $this->assertEquals(9, count($allRows));
@@ -151,11 +149,10 @@ public function testQuery()
 
     public function testActiveQuery()
     {
-        $db = $this->getConnection();
 
         $query = Customer::find()->orderBy('id');
         $customers = [];
-        foreach ($query->batch(2, $db) as $models) {
+        foreach ($query->batch(2) as $models) {
             $customers = array_merge($customers, $models);
         }
         $this->assertEquals(9, count($customers));
@@ -166,7 +163,7 @@ public function testActiveQuery()
         // batch with eager loading
         $query = Customer::find()->with('orders')->orderBy('id');
         $customers = [];
-        foreach ($query->batch(2, $db) as $models) {
+        foreach ($query->batch(2) as $models) {
             $customers = array_merge($customers, $models);
             foreach ($models as $model) {
                 $this->assertTrue($model->isRelationPopulated('orders'));
diff --git a/tests/CacheTest.php b/tests/CacheTest.php
index 16050d511..4f3596172 100644
--- a/tests/CacheTest.php
+++ b/tests/CacheTest.php
@@ -26,7 +26,6 @@ protected function createCache()
     {
         return Yii::createObject([
             'class' => Cache::className(),
-            'db' => $this->getConnection(),
             'cacheCollection' => static::$cacheCollection,
             'gcProbability' => 0,
         ]);
diff --git a/tests/CollectionTest.php b/tests/CollectionTest.php
index a18c5330d..7a9c3e25c 100644
--- a/tests/CollectionTest.php
+++ b/tests/CollectionTest.php
@@ -4,6 +4,7 @@
 
 use MongoDB\BSON\ObjectID;
 use MongoDB\Driver\Cursor;
+use yii;
 
 class CollectionTest extends TestCase
 {
@@ -19,21 +20,21 @@ protected function tearDown()
     public function testGetName()
     {
         $collectionName = 'customer';
-        $collection = $this->getConnection()->getCollection($collectionName);
+        $collection = yii::$app->mongodb->getCollection($collectionName);
         $this->assertEquals($collectionName, $collection->name);
-        $this->assertEquals($this->getConnection()->getDefaultDatabaseName() . '.' . $collectionName, $collection->getFullName());
+        $this->assertEquals(yii::$app->mongodb->getDefaultDatabaseName() . '.' . $collectionName, $collection->getFullName());
     }
 
     public function testFind()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $cursor = $collection->find();
         $this->assertTrue($cursor instanceof Cursor);
     }
 
     public function testInsert()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $data = [
             'name' => 'customer 1',
             'address' => 'customer 1 address',
@@ -49,7 +50,7 @@ public function testInsert()
      */
     public function testFindOne()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $data = [
             'name' => 'customer 1',
             'address' => 'customer 1 address',
@@ -69,7 +70,7 @@ public function testFindOne()
      */
     public function testFindAll()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $data = [
             'name' => 'customer 1',
             'address' => 'customer 1 address',
@@ -90,7 +91,7 @@ public function testFindAll()
      */
     public function testBatchInsert()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $rows = [
             [
                 'name' => 'customer 1',
@@ -109,7 +110,7 @@ public function testBatchInsert()
 
     public function testSave()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $data = [
             'name' => 'customer 1',
             'address' => 'customer 1 address',
@@ -124,7 +125,7 @@ public function testSave()
      */
     public function testUpdateBySave()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $data = [
             'name' => 'customer 1',
             'address' => 'customer 1 address',
@@ -145,7 +146,7 @@ public function testUpdateBySave()
      */
     public function testRemove()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $data = [
             'name' => 'customer 1',
             'address' => 'customer 1 address',
@@ -165,7 +166,7 @@ public function testRemove()
      */
     public function testRemoveComplexCondition()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $collection->batchInsert([
             [
                 'name' => 'customer 1',
@@ -193,7 +194,7 @@ public function testRemoveComplexCondition()
      */
     public function testUpdate()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $data = [
             'name' => 'customer 1',
             'address' => 'customer 1 address',
@@ -215,7 +216,7 @@ public function testUpdate()
      */
     public function testGroup()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $rows = [
             [
                 'name' => 'customer 1',
@@ -239,7 +240,7 @@ public function testGroup()
 
     public function testFindAndModify()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $rows = [
             [
                 'name' => 'customer 1',
@@ -294,7 +295,7 @@ public function testFindAndModify()
      */
     public function testMapReduce()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $rows = [
             [
                 'name' => 'customer 1',
@@ -327,7 +328,7 @@ public function testMapReduce()
         );
         $this->assertEquals('mapReduceOut', $result);
 
-        $outputCollection = $this->getConnection()->getCollection($result);
+        $outputCollection = yii::$app->mongodb->getCollection($result);
         $rows = $this->findAll($outputCollection);
         $expectedRows = [
             [
@@ -347,7 +348,7 @@ public function testMapReduce()
      */
     public function testMapReduceInline()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $rows = [
             [
                 'name' => 'customer 1',
@@ -393,7 +394,7 @@ public function testMapReduceInline()
 
     public function testCreateIndex()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $columns = [
             'name',
             'status' => SORT_DESC
@@ -408,7 +409,7 @@ public function testCreateIndex()
      */
     public function testDropIndex()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
 
         $collection->createIndex('name');
         $this->assertTrue($collection->dropIndex('name'));
@@ -425,7 +426,7 @@ public function testDropIndex()
      */
     public function testDropIndexWithPlugin()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
 
         $columns = [
             'name' => 'text'
@@ -442,7 +443,7 @@ public function testDropIndexWithPlugin()
      */
     public function testDropAllIndexes()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $collection->createIndex('name');
         $this->assertEquals(2, $collection->dropAllIndexes());
         $indexInfo = $collection->listIndexes();
@@ -451,7 +452,7 @@ public function testDropAllIndexes()
 
     public function testCreateIndexes()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $columns = [
             ['key' => ['name']],
             ['key' => ['status' => SORT_DESC]]
@@ -466,7 +467,7 @@ public function testCreateIndexes()
      */
     public function testDropIndexes()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $columns = [
             [
                 'key' => ['name'],
@@ -491,7 +492,7 @@ public function testDropIndexes()
      */
     public function testFindByNotObjectId()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
 
         $data = [
             'name' => 'customer 1',
@@ -516,7 +517,7 @@ public function testFindByNotObjectId()
      */
     public function testInsertMongoBin()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
 
         $fileName = __FILE__;
         $data = [
@@ -534,7 +535,7 @@ public function testInsertMongoBin()
      */
     public function testDistinct()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
 
         $rows = [
             [
diff --git a/tests/CommandTest.php b/tests/CommandTest.php
index d7660d155..2b3a41c77 100644
--- a/tests/CommandTest.php
+++ b/tests/CommandTest.php
@@ -4,6 +4,7 @@
 
 use MongoDB\BSON\ObjectID;
 use MongoDB\Driver\Cursor;
+use yii;
 use yii\helpers\ArrayHelper;
 
 class CommandTest extends TestCase
@@ -16,7 +17,7 @@ protected function tearDown()
 
     public function testCreateCollection()
     {
-        $command = $this->getConnection()->createCommand();
+        $command = yii::$app->mongodb->createCommand();
         $this->assertTrue($command->createCollection('customer'));
     }
 
@@ -25,20 +26,20 @@ public function testCreateCollection()
      */
     public function testDropCollection()
     {
-        $command = $this->getConnection()->createCommand();
+        $command = yii::$app->mongodb->createCommand();
         $command->createCollection('customer');
         $this->assertTrue($command->dropCollection('customer'));
     }
 
     public function testCount()
     {
-        $command = $this->getConnection()->createCommand();
+        $command = yii::$app->mongodb->createCommand();
         $this->assertEquals(0, $command->count('customer'));
     }
 
     public function testCreateIndexes()
     {
-        $command = $this->getConnection()->createCommand();
+        $command = yii::$app->mongodb->createCommand();
         $this->assertTrue($command->createIndexes('customer', [
             [
                 'key' => ['name' => +1],
@@ -57,7 +58,7 @@ public function testCreateIndexes()
      */
     public function testListIndexes()
     {
-        $command = $this->getConnection()->createCommand();
+        $command = yii::$app->mongodb->createCommand();
         $command->createIndexes('customer', [
             [
                 'key' => ['name' => +1],
@@ -75,7 +76,7 @@ public function testListIndexes()
      */
     public function testDropIndexes()
     {
-        $command = $this->getConnection()->createCommand();
+        $command = yii::$app->mongodb->createCommand();
         $command->createIndexes('customer', [
             [
                 'key' => ['name' => +1],
@@ -100,7 +101,7 @@ public function testDropIndexes()
 
     public function testInsert()
     {
-        $command = $this->getConnection()->createCommand();
+        $command = yii::$app->mongodb->createCommand();
         $insertedId = $command->insert('customer', ['name' => 'John']);
         $this->assertTrue($insertedId instanceof ObjectID);
     }
@@ -110,7 +111,7 @@ public function testInsert()
      */
     public function testBatchInsert()
     {
-        $command = $this->getConnection()->createCommand();
+        $command = yii::$app->mongodb->createCommand();
         $insertedIds = $command->batchInsert('customer', [
             ['name' => 'John'],
             ['name' => 'Sara'],
@@ -124,11 +125,10 @@ public function testBatchInsert()
      */
     public function testUpdate()
     {
-        $connection = $this->getConnection();
 
-        $newRecordId = $connection->createCommand()->insert('customer', ['name' => 'John']);
+        $newRecordId = yii::$app->mongodb->createCommand()->insert('customer', ['name' => 'John']);
 
-        $result = $connection->createCommand()->update('customer', ['_id' => $newRecordId], ['name' => 'Mike']);
+        $result = yii::$app->mongodb->createCommand()->update('customer', ['_id' => $newRecordId], ['name' => 'Mike']);
 
         $this->assertEquals(1, $result->getModifiedCount());
     }
@@ -138,11 +138,10 @@ public function testUpdate()
      */
     public function testDelete()
     {
-        $connection = $this->getConnection();
 
-        $newRecordId = $connection->createCommand()->insert('customer', ['name' => 'John']);
+        $newRecordId = yii::$app->mongodb->createCommand()->insert('customer', ['name' => 'John']);
 
-        $result = $connection->createCommand()->delete('customer', ['_id' => $newRecordId]);
+        $result = yii::$app->mongodb->createCommand()->delete('customer', ['_id' => $newRecordId]);
 
         $this->assertEquals(1, $result->getDeletedCount());
     }
@@ -152,11 +151,10 @@ public function testDelete()
      */
     public function testFind()
     {
-        $connection = $this->getConnection();
 
-        $connection->createCommand()->insert('customer', ['name' => 'John']);
+        yii::$app->mongodb->createCommand()->insert('customer', ['name' => 'John']);
 
-        $cursor = $connection->createCommand()->find('customer', []);
+        $cursor = yii::$app->mongodb->createCommand()->find('customer', []);
         $rows = $cursor->toArray();
         $this->assertCount(1, $rows);
         $this->assertEquals('John', $rows[0]['name']);
@@ -167,7 +165,6 @@ public function testFind()
      */
     public function testFindAndModify()
     {
-        $connection = $this->getConnection();
         $rows = [
             [
                 'name' => 'customer 1',
@@ -180,20 +177,20 @@ public function testFindAndModify()
                 'amount' => 200,
             ],
         ];
-        $command = $connection->createCommand();
+        $command = yii::$app->mongodb->createCommand();
         $command->batchInsert('customer', $rows);
 
         // increment field
-        $result = $connection->createCommand()->findAndModify('customer', ['name' => 'customer 1'], ['$inc' => ['status' => 1]]);
+        $result = yii::$app->mongodb->createCommand()->findAndModify('customer', ['name' => 'customer 1'], ['$inc' => ['status' => 1]]);
         $this->assertEquals('customer 1', $result['name']);
         $this->assertEquals(1, $result['status']);
 
-        $cursor = $connection->createCommand()->find('customer', ['name' => 'customer 1']);
+        $cursor = yii::$app->mongodb->createCommand()->find('customer', ['name' => 'customer 1']);
         $newResult = current($cursor->toArray());
         $this->assertEquals(2, $newResult['status']);
 
         // $set and return modified document
-        $result = $connection->createCommand()->findAndModify(
+        $result = yii::$app->mongodb->createCommand()->findAndModify(
             'customer',
             ['name' => 'customer 2'],
             ['$set' => ['status' => 2]],
@@ -207,7 +204,7 @@ public function testFindAndModify()
             'name' => 'customer 3',
             'city' => 'Minsk'
         ];
-        $result = $connection->createCommand()->findAndModify(
+        $result = yii::$app->mongodb->createCommand()->findAndModify(
             'customer',
             ['name' => 'customer 2'],
             $data,
@@ -219,7 +216,7 @@ public function testFindAndModify()
 
         // Test exceptions
         $this->expectException('\yii\mongodb\Exception');
-        $connection->createCommand()->findAndModify('customer',['name' => 'customer 1'], ['$wrongOperator' => ['status' => 1]]);
+        yii::$app->mongodb->createCommand()->findAndModify('customer',['name' => 'customer 1'], ['$wrongOperator' => ['status' => 1]]);
     }
 
     /**
@@ -227,7 +224,6 @@ public function testFindAndModify()
      */
     public function testAggregate()
     {
-        $connection = $this->getConnection();
         $rows = [
             [
                 'name' => 'customer 1',
@@ -240,7 +236,7 @@ public function testAggregate()
                 'amount' => 200,
             ],
         ];
-        $command = $connection->createCommand();
+        $command = yii::$app->mongodb->createCommand();
         $command->batchInsert('customer', $rows);
 
         $pipelines = [
@@ -256,7 +252,7 @@ public function testAggregate()
                 ]
             ]
         ];
-        $result = $connection->createCommand()->aggregate('customer', $pipelines);
+        $result = yii::$app->mongodb->createCommand()->aggregate('customer', $pipelines);
 
         $this->assertEquals(['_id' => '1', 'total' => 300], $result[0]);
     }
@@ -268,7 +264,6 @@ public function testAggregate()
      */
     public function testAggregateCursor()
     {
-        $connection = $this->getConnection();
         $rows = [
             [
                 'name' => 'customer 1',
@@ -291,7 +286,7 @@ public function testAggregateCursor()
                 'amount' => 200,
             ],
         ];
-        $command = $connection->createCommand();
+        $command = yii::$app->mongodb->createCommand();
         $command->batchInsert('customer', $rows);
 
         $pipelines = [
@@ -307,7 +302,7 @@ public function testAggregateCursor()
                 ]
             ]
         ];
-        $result = $connection->createCommand()->aggregate('customer', $pipelines, ['cursor' => ['batchSize' => 2]]);
+        $result = yii::$app->mongodb->createCommand()->aggregate('customer', $pipelines, ['cursor' => ['batchSize' => 2]]);
         $this->assertTrue($result instanceof Cursor);
 
         $this->assertEquals(['_id' => '1', 'total' => 600], $result->toArray()[0]);
@@ -318,11 +313,10 @@ public function testAggregateCursor()
      */
     public function testExplain()
     {
-        $connection = $this->getConnection();
 
-        $connection->createCommand()->insert('customer', ['name' => 'John']);
+        yii::$app->mongodb->createCommand()->insert('customer', ['name' => 'John']);
 
-        $result = $connection->createCommand()->explain('customer', [
+        $result = yii::$app->mongodb->createCommand()->explain('customer', [
             'filter' => [
                 'name' => 'John'
             ],
@@ -337,11 +331,10 @@ public function testExplain()
      */
     public function testListCollections()
     {
-        $connection = $this->getConnection();
 
-        $connection->createCommand()->createCollection('customer');
+        yii::$app->mongodb->createCommand()->createCollection('customer');
 
-        $collections = $connection->createCommand()->listCollections();
+        $collections = yii::$app->mongodb->createCommand()->listCollections();
         $collectionNames = ArrayHelper::getColumn($collections, 'name');
         $this->assertContains('customer', $collectionNames);
     }
@@ -354,22 +347,21 @@ public function testListCollections()
      */
     public function testUpdateUpsert()
     {
-        $connection = $this->getConnection();
 
-        $connection->createCommand()->insert('customer', ['name' => 'John']);
+        yii::$app->mongodb->createCommand()->insert('customer', ['name' => 'John']);
 
-        $result = $connection->createCommand()
+        $result = yii::$app->mongodb->createCommand()
             ->update('customer', ['name' => 'Mike'], ['name' => 'Jack']);
 
         $this->assertEquals(0, $result->getModifiedCount());
         $this->assertEquals(0, $result->getUpsertedCount());
-        $this->assertEquals(1, $connection->createCommand()->count('customer'));
+        $this->assertEquals(1, yii::$app->mongodb->createCommand()->count('customer'));
 
-        $result = $connection->createCommand()
+        $result = yii::$app->mongodb->createCommand()
             ->update('customer', ['name' => 'Mike'], ['name' => 'Jack'], ['upsert' => true]);
 
         $this->assertEquals(0, $result->getModifiedCount());
         $this->assertEquals(1, $result->getUpsertedCount());
-        $this->assertEquals(2, $connection->createCommand()->count('customer'));
+        $this->assertEquals(2, yii::$app->mongodb->createCommand()->count('customer'));
     }
 }
\ No newline at end of file
diff --git a/tests/ConnectionTest.php b/tests/ConnectionTest.php
index a3665a662..123ff4a53 100644
--- a/tests/ConnectionTest.php
+++ b/tests/ConnectionTest.php
@@ -2,6 +2,7 @@
 
 namespace yiiunit\extensions\mongodb;
 
+use yii;
 use yii\mongodb\Collection;
 use yii\mongodb\Command;
 use yii\mongodb\file\Collection as FileCollection;
@@ -13,7 +14,7 @@ class ConnectionTest extends TestCase
 {
     public function testConstruct()
     {
-        $connection = $this->getConnection(false);
+        $connection = $this->getConnection(true,false);
         $params = $this->mongoDbConfig;
 
         $connection->open();
@@ -25,7 +26,7 @@ public function testConstruct()
 
     public function testOpenClose()
     {
-        $connection = $this->getConnection(false, false);
+        $connection = $this->getConnection(true, false);
 
         $this->assertFalse($connection->isActive);
         $this->assertEquals(null, $connection->manager);
@@ -46,17 +47,16 @@ public function testOpenClose()
 
     public function testGetDatabase()
     {
-        $connection = $this->getConnection();
 
-        $database = $connection->getDatabase($connection->defaultDatabaseName);
+        $database = yii::$app->mongodb->getDatabase(yii::$app->mongodb->defaultDatabaseName);
         $this->assertTrue($database instanceof Database);
-        $this->assertSame($connection, $database->connection);
-        $this->assertSame($connection->defaultDatabaseName, $database->name);
+        $this->assertSame(yii::$app->mongodb, $database->connection);
+        $this->assertSame(yii::$app->mongodb->defaultDatabaseName, $database->name);
 
-        $database2 = $connection->getDatabase($connection->defaultDatabaseName);
+        $database2 = yii::$app->mongodb->getDatabase(yii::$app->mongodb->defaultDatabaseName);
         $this->assertTrue($database === $database2);
 
-        $databaseRefreshed = $connection->getDatabase($connection->defaultDatabaseName, true);
+        $databaseRefreshed = yii::$app->mongodb->getDatabase(yii::$app->mongodb->defaultDatabaseName, true);
         $this->assertFalse($database === $databaseRefreshed);
     }
 
@@ -110,15 +110,14 @@ public function testGetDefaultDatabase()
      */
     public function testGetCollection()
     {
-        $connection = $this->getConnection();
 
-        $collection = $connection->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $this->assertTrue($collection instanceof Collection);
 
-        $collection2 = $connection->getCollection('customer');
+        $collection2 = yii::$app->mongodb->getCollection('customer');
         $this->assertTrue($collection === $collection2);
 
-        $collection2 = $connection->getCollection('customer', true);
+        $collection2 = yii::$app->mongodb->getCollection('customer', true);
         $this->assertFalse($collection === $collection2);
     }
 
@@ -127,31 +126,28 @@ public function testGetCollection()
      */
     public function testGetFileCollection()
     {
-        $connection = $this->getConnection();
 
-        $collection = $connection->getFileCollection('testfs');
+        $collection = yii::$app->mongodb->getFileCollection('testfs');
         $this->assertTrue($collection instanceof FileCollection);
 
-        $collection2 = $connection->getFileCollection('testfs');
+        $collection2 = yii::$app->mongodb->getFileCollection('testfs');
         $this->assertTrue($collection === $collection2);
 
-        $collection2 = $connection->getFileCollection('testfs', true);
+        $collection2 = yii::$app->mongodb->getFileCollection('testfs', true);
         $this->assertFalse($collection === $collection2);
     }
 
     public function testGetQueryBuilder()
     {
-        $connection = $this->getConnection();
 
-        $this->assertTrue($connection->getQueryBuilder() instanceof QueryBuilder);
+        $this->assertTrue(yii::$app->mongodb->getQueryBuilder() instanceof QueryBuilder);
     }
 
     public function testCreateCommand()
     {
-        $connection = $this->getConnection();
 
-        $command = $connection->createCommand();
+        $command = yii::$app->mongodb->createCommand();
         $this->assertTrue($command instanceof Command);
-        $this->assertSame($connection, $command->db);
+        $this->assertSame(yii::$app->mongodb, $command->db);
     }
 }
diff --git a/tests/DatabaseTest.php b/tests/DatabaseTest.php
index 35700bb29..5999d8378 100644
--- a/tests/DatabaseTest.php
+++ b/tests/DatabaseTest.php
@@ -2,6 +2,7 @@
 
 namespace yiiunit\extensions\mongodb;
 
+use yii;
 use yii\mongodb\Collection;
 use yii\mongodb\Command;
 use yii\mongodb\file\Collection as FileCollection;
@@ -19,7 +20,7 @@ protected function tearDown()
 
     public function testGetCollection()
     {
-        $database = $this->getConnection()->getDatabase();
+        $database = yii::$app->mongodb->getDatabase();
 
         $collection = $database->getCollection('customer');
         $this->assertTrue($collection instanceof Collection);
@@ -34,7 +35,7 @@ public function testGetCollection()
 
     public function testGetFileCollection()
     {
-        $database = $this->getConnection()->getDatabase();
+        $database = yii::$app->mongodb->getDatabase();
 
         $collection = $database->getFileCollection('testfs');
         $this->assertTrue($collection instanceof FileCollection);
@@ -49,7 +50,7 @@ public function testGetFileCollection()
 
     public function testCreateCommand()
     {
-        $database = $this->getConnection()->getDatabase();
+        $database = yii::$app->mongodb->getDatabase();
 
         $command = $database->createCommand();
         $this->assertTrue($command instanceof Command);
@@ -58,7 +59,7 @@ public function testCreateCommand()
 
     public function testCreateCollection()
     {
-        $database = $this->getConnection()->getDatabase();
+        $database = yii::$app->mongodb->getDatabase();
         $this->assertTrue($database->createCollection('customer'));
     }
 }
diff --git a/tests/LogBuilderTest.php b/tests/LogBuilderTest.php
index 08b9c9b29..83bc5c4c0 100644
--- a/tests/LogBuilderTest.php
+++ b/tests/LogBuilderTest.php
@@ -4,6 +4,7 @@
 
 use MongoDB\BSON\Javascript;
 use MongoDB\BSON\ObjectID;
+use yii;
 
 class LogBuilderTest extends TestCase
 {
@@ -37,7 +38,7 @@ public function dataProviderEncodeData()
      */
     public function testEncodeData($data, $expectedResult)
     {
-        $logBuilder = $this->getConnection()->getLogBuilder();
+        $logBuilder = yii::$app->mongodb->getLogBuilder();
         $this->assertTrue(strcasecmp($expectedResult, $logBuilder->encodeData($data)) === 0);
     }
 }
\ No newline at end of file
diff --git a/tests/MigrationTest.php b/tests/MigrationTest.php
index a14a8fb51..f7438bb34 100644
--- a/tests/MigrationTest.php
+++ b/tests/MigrationTest.php
@@ -12,19 +12,11 @@ protected function tearDown()
         parent::tearDown();
     }
 
-    /**
-     * @return Migration migration instance.
-     */
-    protected function createMigration()
-    {
-        return new Migration(['db' => $this->getConnection()]);
-    }
-
     // Tests :
 
     public function testCollectionOperations()
     {
-        $migration = $this->createMigration();
+        $migration = new Migration;
 
         $migration->createCollection('customer');
         $this->assertNotEmpty($migration->db->getDatabase()->listCollections(['name' => 'customer']));
@@ -35,7 +27,7 @@ public function testCollectionOperations()
 
     public function testIndexOperations()
     {
-        $migration = $this->createMigration();
+        $migration = new Migration;
 
         $migration->createIndexes('customer', [
             ['key' => 'name']
@@ -58,7 +50,7 @@ public function testIndexOperations()
 
     public function testDataOperations()
     {
-        $migration = $this->createMigration();
+        $migration = new Migration;
 
         $id = $migration->insert('customer', ['name' => 'John Doe']);
         $this->assertTrue($id instanceof ObjectID);
@@ -85,7 +77,7 @@ public function testDataOperations()
      */
     public function testCommandOutput()
     {
-        $migration = $this->createMigration();
+        $migration = new Migration;
 
         $migration->compact = false;
         $migration->createCollection('customer');
diff --git a/tests/QueryRunTest.php b/tests/QueryRunTest.php
index c3a97616f..318da4080 100644
--- a/tests/QueryRunTest.php
+++ b/tests/QueryRunTest.php
@@ -3,6 +3,7 @@
 namespace yiiunit\extensions\mongodb;
 
 use MongoDB\BSON\ObjectID;
+use yii;
 use yii\mongodb\Query;
 
 class QueryRunTest extends TestCase
@@ -24,7 +25,7 @@ protected function tearDown()
      */
     protected function setUpTestRows()
     {
-        $collection = $this->getConnection()->getCollection('customer');
+        $collection = yii::$app->mongodb->getCollection('customer');
         $rows = [];
         for ($i = 1; $i <= 10; $i++) {
             $rows[] = [
@@ -46,43 +47,39 @@ protected function setUpTestRows()
 
     public function testAll()
     {
-        $connection = $this->getConnection();
         $query = new Query();
-        $rows = $query->from('customer')->all($connection);
+        $rows = $query->from('customer')->all();
         $this->assertEquals(10, count($rows));
     }
 
     public function testDirectMatch()
     {
-        $connection = $this->getConnection();
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['name' => 'name1'])
-            ->all($connection);
+            ->all();
         $this->assertEquals(1, count($rows));
         $this->assertEquals('name1', $rows[0]['name']);
     }
 
     public function testIndexBy()
     {
-        $connection = $this->getConnection();
         $query = new Query();
         $rows = $query->from('customer')
             ->indexBy('name')
-            ->all($connection);
+            ->all();
         $this->assertEquals(10, count($rows));
         $this->assertNotEmpty($rows['name1']);
     }
 
     public function testInCondition()
     {
-        $connection = $this->getConnection();
         $query = new Query();
         $rows = $query->from('customer')
             ->where([
                 'name' => ['name1', 'name5']
             ])
-            ->all($connection);
+            ->all();
         $this->assertEquals(2, count($rows));
         $this->assertEquals('name1', $rows[0]['name']);
         $this->assertEquals('name5', $rows[1]['name']);
@@ -90,18 +87,17 @@ public function testInCondition()
 
     public function testNotInCondition()
     {
-        $connection = $this->getConnection();
 
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['not in', 'name', ['name1', 'name5']])
-            ->all($connection);
+            ->all();
         $this->assertEquals(8, count($rows));
 
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['not in', 'name', ['name1']])
-            ->all($connection);
+            ->all();
         $this->assertEquals(9, count($rows));
     }
 
@@ -110,7 +106,6 @@ public function testNotInCondition()
      */
     public function testCompositeInCondition()
     {
-        $connection = $this->getConnection();
         $query = new Query();
         $rows = $query->from('customer')
             ->where([
@@ -122,7 +117,7 @@ public function testCompositeInCondition()
                     ['status' => 5, 'name' => 'name7'],
                 ]
             ])
-            ->all($connection);
+            ->all();
         $this->assertEquals(2, count($rows));
         $this->assertEquals('name1', $rows[0]['name']);
         $this->assertEquals('name3', $rows[1]['name']);
@@ -130,12 +125,11 @@ public function testCompositeInCondition()
 
     public function testOrCondition()
     {
-        $connection = $this->getConnection();
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['name' => 'name1'])
             ->orWhere(['address' => 'address5'])
-            ->all($connection);
+            ->all();
         $this->assertEquals(2, count($rows));
         $this->assertEquals('name1', $rows[0]['name']);
         $this->assertEquals('address5', $rows[1]['address']);
@@ -143,21 +137,19 @@ public function testOrCondition()
 
     public function testCombinedInAndCondition()
     {
-        $connection = $this->getConnection();
         $query = new Query();
         $rows = $query->from('customer')
             ->where([
                 'name' => ['name1', 'name5']
             ])
             ->andWhere(['name' => 'name1'])
-            ->all($connection);
+            ->all();
         $this->assertEquals(1, count($rows));
         $this->assertEquals('name1', $rows[0]['name']);
     }
 
     public function testCombinedInLikeAndCondition()
     {
-        $connection = $this->getConnection();
         $query = new Query();
         $rows = $query->from('customer')
             ->where([
@@ -165,14 +157,13 @@ public function testCombinedInLikeAndCondition()
             ])
             ->andWhere(['LIKE', 'name', 'me1'])
             ->andWhere(['name' => 'name10'])
-            ->all($connection);
+            ->all();
         $this->assertEquals(1, count($rows));
         $this->assertEquals('name10', $rows[0]['name']);
     }
 
     public function testNestedCombinedInAndCondition()
     {
-        $connection = $this->getConnection();
         $query = new Query();
         $rows = $query->from('customer')
             ->where([
@@ -185,7 +176,7 @@ public function testNestedCombinedInAndCondition()
                 ['name' => ['name4', 'name5', 'name6']],
                 ['name' => 'name6']
             ])
-            ->all($connection);
+            ->all();
         $this->assertEquals(2, count($rows));
         $this->assertEquals('name1', $rows[0]['name']);
         $this->assertEquals('name6', $rows[1]['name']);
@@ -193,40 +184,37 @@ public function testNestedCombinedInAndCondition()
 
     public function testOrder()
     {
-        $connection = $this->getConnection();
 
         $query = new Query();
         $rows = $query->from('customer')
             ->orderBy(['name' => SORT_DESC])
-            ->all($connection);
+            ->all();
         $this->assertEquals('name9', $rows[0]['name']);
 
         $query = new Query();
         $rows = $query->from('customer')
             ->orderBy(['avatar.height' => SORT_DESC])
-            ->all($connection);
+            ->all();
         $this->assertEquals('name10', $rows[0]['name']);
     }
 
     public function testMatchPlainId()
     {
-        $connection = $this->getConnection();
         $query = new Query();
-        $row = $query->from('customer')->one($connection);
+        $row = $query->from('customer')->one();
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['_id' => $row['_id']->__toString()])
-            ->all($connection);
+            ->all();
         $this->assertEquals(1, count($rows));
     }
 
     public function testRegex()
     {
-        $connection = $this->getConnection();
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['REGEX', 'name', '/me1/'])
-            ->all($connection);
+            ->all();
         $this->assertEquals(2, count($rows));
         $this->assertEquals('name1', $rows[0]['name']);
         $this->assertEquals('name10', $rows[1]['name']);
@@ -234,12 +222,11 @@ public function testRegex()
 
     public function testLike()
     {
-        $connection = $this->getConnection();
 
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['LIKE', 'name', 'me1'])
-            ->all($connection);
+            ->all();
         $this->assertEquals(2, count($rows));
         $this->assertEquals('name1', $rows[0]['name']);
         $this->assertEquals('name10', $rows[1]['name']);
@@ -247,76 +234,72 @@ public function testLike()
         $query = new Query();
         $rowsUppercase = $query->from('customer')
             ->where(['LIKE', 'name', 'ME1'])
-            ->all($connection);
+            ->all();
         $this->assertEquals($rows, $rowsUppercase);
     }
 
     public function testCompare()
     {
-        $connection = $this->getConnection();
 
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['$gt', 'status', 8])
-            ->all($connection);
+            ->all();
         $this->assertEquals(2, count($rows));
 
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['>', 'status', 8])
-            ->all($connection);
+            ->all();
         $this->assertEquals(2, count($rows));
 
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['<=', 'status', 3])
-            ->all($connection);
+            ->all();
         $this->assertEquals(3, count($rows));
     }
 
     public function testNot()
     {
-        $connection = $this->getConnection();
 
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['not', 'status', ['$gte' => 10]])
-            ->all($connection);
+            ->all();
         $this->assertEquals(9, count($rows));
 
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['not', 'name', 'name1'])
-            ->all($connection);
+            ->all();
         $this->assertEquals(9, count($rows));
 
         $query = new Query();
         $rows = $query->from('customer')
             ->where(['not', 'name', null])
-            ->all($connection);
+            ->all();
         $this->assertEquals(10, count($rows));
     }
 
     public function testExists()
     {
-        $connection = $this->getConnection();
 
         $query = new Query();
         $exists = $query->from('customer')
             ->where(['name' => 'name1'])
-            ->exists($connection);
+            ->exists();
         $this->assertTrue($exists);
 
         $query = new Query();
         $exists = $query->from('customer')
             ->where(['name' => 'un-existing-name'])
-            ->exists($connection);
+            ->exists();
         $this->assertFalse($exists);
     }
 
     public function testModify()
     {
-        $connection = $this->getConnection();
 
         $query = new Query();
 
@@ -324,19 +307,19 @@ public function testModify()
         $newName = 'new name';
         $row = $query->from('customer')
             ->where(['name' => $searchName])
-            ->modify(['$set' => ['name' => $newName]], ['new' => false], $connection);
+            ->modify(['$set' => ['name' => $newName]], ['new' => false]);
         $this->assertEquals($searchName, $row['name']);
 
         $searchName = 'name7';
         $newName = 'new name';
         $row = $query->from('customer')
             ->where(['name' => $searchName])
-            ->modify(['$set' => ['name' => $newName]], ['new' => true], $connection);
+            ->modify(['$set' => ['name' => $newName]], ['new' => true]);
         $this->assertEquals($newName, $row['name']);
 
         $row = $query->from('customer')
             ->where(['name' => 'not existing name'])
-            ->modify(['$set' => ['name' => 'new name']], ['new' => false], $connection);
+            ->modify(['$set' => ['name' => 'new name']], ['new' => false]);
         $this->assertNull($row);
     }
 
@@ -348,7 +331,6 @@ public function testModify()
      */
     public function testInConditionIgnoreKeys()
     {
-        $connection = $this->getConnection();
         $query = new Query();
         $rows = $query->from('customer')
             /*->where([
@@ -361,7 +343,7 @@ public function testInConditionIgnoreKeys()
                 10 => 'name1',
                 15 => 'name5'
             ]])
-            ->all($connection);
+            ->all();
         $this->assertEquals(2, count($rows));
         $this->assertEquals('name1', $rows[0]['name']);
         $this->assertEquals('name5', $rows[1]['name']);
@@ -373,7 +355,7 @@ public function testInConditionIgnoreKeys()
                 10 => $rows[0]['_id'],
                 15 => $rows[1]['_id']
             ]])
-            ->all($connection);
+            ->all();
         $this->assertEquals(2, count($rows));
     }
 
@@ -382,12 +364,11 @@ public function testInConditionIgnoreKeys()
      */
     public function testSelect()
     {
-        $connection = $this->getConnection();
         $query = new Query();
         $rows = $query->from('customer')
             ->select(['name' => true, '_id' => false])
             ->limit(1)
-            ->all($connection);
+            ->all();
         $row = array_pop($rows);
         $this->assertArrayHasKey('name', $row);
         $this->assertArrayNotHasKey('address', $row);
@@ -396,21 +377,20 @@ public function testSelect()
 
     public function testScalar()
     {
-        $connection = $this->getConnection();
 
         $result = (new Query())
             ->select(['name' => true, '_id' => false])
             ->from('customer')
             ->orderBy(['name' => SORT_ASC])
             ->limit(1)
-            ->scalar($connection);
+            ->scalar();
         $this->assertSame('name1', $result);
 
         $result = (new Query())
             ->select(['name' => true, '_id' => false])
             ->from('customer')
             ->andWhere(['status' => -1])
-            ->scalar($connection);
+            ->scalar();
         $this->assertSame(false, $result);
 
         $result = (new Query())
@@ -418,26 +398,25 @@ public function testScalar()
             ->from('customer')
             ->orderBy(['name' => SORT_ASC])
             ->limit(1)
-            ->scalar($connection);
+            ->scalar();
         $this->assertSame('name1', $result);
 
         $result = (new Query())
             ->select(['_id'])
             ->from('customer')
             ->limit(1)
-            ->scalar($connection);
+            ->scalar();
         $this->assertTrue($result instanceof ObjectID);
     }
 
     public function testColumn()
     {
-        $connection = $this->getConnection();
 
         $result = (new Query())->from('customer')
             ->select(['name' => true, '_id' => false])
             ->orderBy(['name' => SORT_ASC])
             ->limit(2)
-            ->column($connection);
+            ->column();
         $this->assertEquals(['name1', 'name10'], $result);
 
         $result = (new Query())->from('customer')
@@ -445,21 +424,21 @@ public function testColumn()
             ->andWhere(['status' => -1])
             ->orderBy(['name' => SORT_ASC])
             ->limit(2)
-            ->column($connection);
+            ->column();
         $this->assertEquals([], $result);
 
         $result = (new Query())->from('customer')
             ->select(['name'])
             ->orderBy(['name' => SORT_ASC])
             ->limit(2)
-            ->column($connection);
+            ->column();
         $this->assertEquals(['name1', 'name10'], $result);
 
         $result = (new Query())->from('customer')
             ->select(['_id'])
             ->orderBy(['name' => SORT_ASC])
             ->limit(2)
-            ->column($connection);
+            ->column();
         $this->assertTrue($result[0] instanceof ObjectID);
         $this->assertTrue($result[1] instanceof ObjectID);
     }
@@ -469,14 +448,13 @@ public function testColumn()
      */
     public function testColumnIndexBy()
     {
-        $connection = $this->getConnection();
 
         $result = (new Query())->from('customer')
             ->select(['name'])
             ->orderBy(['name' => SORT_ASC])
             ->limit(2)
             ->indexBy('status')
-            ->column($connection);
+            ->column();
         $this->assertEquals([1 => 'name1', 10 => 'name10'], $result);
 
         $result = (new Query())->from('customer')
@@ -486,7 +464,7 @@ public function testColumnIndexBy()
             ->indexBy(function ($row) {
                 return $row['status'] * 2;
             })
-            ->column($connection);
+            ->column();
         $this->assertEquals([2 => 'name1', 20 => 'name10'], $result);
 
         $result = (new Query())->from('customer')
@@ -494,7 +472,7 @@ public function testColumnIndexBy()
             ->orderBy(['name' => SORT_ASC])
             ->limit(2)
             ->indexBy('name')
-            ->column($connection);
+            ->column();
         $this->assertEquals(['name1' => 'name1', 'name10' => 'name10'], $result);
     }
 
@@ -505,84 +483,82 @@ public function testEmulateExecution()
             $this->markTestSkipped('"yii2" version 2.0.11 or higher required');
         }
 
-        $db = $this->getConnection();
-
-        $this->assertGreaterThan(0, $query->from('customer')->count('*', $db));
+        $this->assertGreaterThan(0, $query->from('customer')->count());
 
         $rows = (new Query())
             ->from('customer')
             ->emulateExecution()
-            ->all($db);
+            ->all();
         $this->assertSame([], $rows);
 
         $row = (new Query())
             ->from('customer')
             ->emulateExecution()
-            ->one($db);
+            ->one();
         $this->assertSame(false, $row);
 
         $exists = (new Query())
             ->from('customer')
             ->emulateExecution()
-            ->exists($db);
+            ->exists();
         $this->assertSame(false, $exists);
 
         $count = (new Query())
             ->from('customer')
             ->emulateExecution()
-            ->count('*', $db);
+            ->count();
         $this->assertSame(0, $count);
 
         $sum = (new Query())
             ->from('customer')
             ->emulateExecution()
-            ->sum('id', $db);
+            ->sum('id');
         $this->assertSame(0, $sum);
 
         $sum = (new Query())
             ->from('customer')
             ->emulateExecution()
-            ->average('id', $db);
+            ->average('id');
         $this->assertSame(0, $sum);
 
         $max = (new Query())
             ->from('customer')
             ->emulateExecution()
-            ->max('id', $db);
+            ->max('id');
         $this->assertSame(null, $max);
 
         $min = (new Query())
             ->from('customer')
             ->emulateExecution()
-            ->min('id', $db);
+            ->min('id');
         $this->assertSame(null, $min);
 
         $scalar = (new Query())
             ->select(['id'])
             ->from('customer')
             ->emulateExecution()
-            ->scalar($db);
+            ->scalar();
         $this->assertSame(null, $scalar);
 
         $column = (new Query())
             ->select(['id'])
             ->from('customer')
             ->emulateExecution()
-            ->column($db);
+            ->column();
         $this->assertSame([], $column);
 
         $row = (new Query())
             ->select(['id'])
             ->from('customer')
             ->emulateExecution()
-            ->modify(['name' => 'new name'], [], $db);
+            ->modify(['name' => 'new name']);
         $this->assertSame(null, $row);
 
         $values = (new Query())
             ->select(['id'])
             ->from('customer')
             ->emulateExecution()
-            ->distinct('name', $db);
+            ->distinct('name');
         $this->assertSame([], $values);
     }
 
@@ -593,18 +569,17 @@ public function testEmulateExecution()
      */
     public function testOffsetLimit()
     {
-        $db = $this->getConnection();
 
         $rows = (new Query())
             ->from('customer')
             ->limit(2)
-            ->all($db);
+            ->all();
         $this->assertCount(2, $rows);
 
         $rows = (new Query())
             ->from('customer')
             ->limit(-1)
-            ->all($db);
+            ->all();
         $this->assertCount(10, $rows);
 
         $rows = (new Query())
@@ -612,7 +587,7 @@ public function testOffsetLimit()
             ->orderBy(['name' => SORT_ASC])
             ->offset(2)
             ->limit(1)
-            ->all($db);
+            ->all();
         $this->assertCount(1, $rows);
         $this->assertEquals('name2', $rows[0]['name']);
 
@@ -621,54 +596,55 @@ public function testOffsetLimit()
             ->orderBy(['name' => SORT_ASC])
             ->offset(-1)
             ->limit(1)
-            ->all($db);
+            ->all();
         $this->assertCount(1, $rows);
         $this->assertEquals('name1', $rows[0]['name']);
     }
 
     public function testDistinct()
     {
-        $db = $this->getConnection();
 
         $rows = (new Query())
             ->from('customer')
-            ->distinct('group', $db);
+            ->distinct('group');
+
+        #difference order after php 7
+        sort($rows);
 
-        $this->assertSame(['odd', 'even'], $rows);
+        $this->assertSame(['even', 'odd'], $rows);
     }
 
     public function testAggregationShortcuts()
     {
-        $db = $this->getConnection();
 
         $max = (new Query())
             ->from('customer')
             ->where(['group' => 'odd'])
-            ->count('*', $db);
+            ->count();
         $this->assertSame(5, $max);
 
         $max = (new Query())
             ->from('customer')
             ->where(['group' => 'even'])
-            ->max('status', $db);
+            ->max('status');
         $this->assertSame(10, $max);
 
         $max = (new Query())
             ->from('customer')
             ->where(['group' => 'even'])
-            ->min('status', $db);
+            ->min('status');
         $this->assertSame(2, $max);
 
         $max = (new Query())
             ->from('customer')
             ->where(['group' => 'even'])
-            ->sum('status', $db);
+            ->sum('status');
         $this->assertSame(30, $max);
 
         $max = (new Query())
             ->from('customer')
             ->where(['group' => 'even'])
-            ->average('status', $db);
+            ->average('status');
         $this->assertEquals(6, $max);
     }
 }
\ No newline at end of file
diff --git a/tests/SessionTest.php b/tests/SessionTest.php
index b1f8e5173..77c4c68e5 100755
--- a/tests/SessionTest.php
+++ b/tests/SessionTest.php
@@ -26,7 +26,6 @@ protected function createSession()
     {
         return Yii::createObject([
             'class' => Session::className(),
-            'db' => $this->getConnection(),
             'sessionCollection' => static::$sessionCollection,
         ]);
     }
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 7c876e453..df91a00a6 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -34,7 +34,7 @@ protected function setUp()
         if (!empty($config)) {
             $this->mongoDbConfig = $config;
         }
-        //$this->mockApplication();
+        $this->mockApplication();
     }
 
     protected function tearDown()
@@ -74,6 +74,9 @@ protected function mockApplication($config = [], $appClass = '\yii\console\Appli
             'basePath' => __DIR__,
             'vendorPath' => $this->getVendorPath(),
             'runtimePath' => dirname(__DIR__) . '/runtime',
+            'components' => [
+                'mongodb' => $this->getConnection(),
+            ],
         ], $config));
     }
 
diff --git a/tests/console/controllers/MigrateControllerTest.php b/tests/console/controllers/MigrateControllerTest.php
index 44b821c2e..593860532 100644
--- a/tests/console/controllers/MigrateControllerTest.php
+++ b/tests/console/controllers/MigrateControllerTest.php
@@ -47,22 +47,17 @@ public function setUp()
         $this->migrationNamespace = 'yiiunit\extensions\mongodb\runtime\test_migrations';
 
         $this->setUpMigrationPath();
-
-        $this->mockApplication();
-        Yii::$app->setComponents(['mongodb' => $this->getConnection()]);
     }
 
     public function tearDown()
     {
-        parent::tearDown();
-        if (extension_loaded('mongodb')) {
-            try {
-                $this->getConnection()->getCollection('migration')->drop();
-            } catch (Exception $e) {
-                // shutdown exception
-            }
+        try {
+            yii::$app->mongodb->getCollection('migration')->drop();
+        } catch (Exception $e) {
+            // shutdown exception
         }
         $this->tearDownMigrationPath();
+        parent::tearDown();
     }
 
     public function setUpMigrationPath()
@@ -501,7 +496,6 @@ public function testNamespaceTo()
      */
     public function testGetMigrationHistory()
     {
-        $connection = $this->getConnection();
 
         $controllerConfig = [
             'migrationPath' => null,
@@ -509,9 +503,9 @@ public function testGetMigrationHistory()
         ];
 
         $controller = $this->createMigrateController($controllerConfig);
-        $controller->db = $this->getConnection();
+        $controller->db = yii::$app->mongodb;
 
-        $connection->createCommand()->batchInsert('migration', [
+        yii::$app->mongodb->createCommand()->batchInsert('migration', [
             [
                 'version' => 'app\migrations\M140506102106One',
                 'apply_time' => 10,
@@ -574,9 +568,7 @@ public function testRefreshMigration()
             $this->markTestSkipped('Method "yii\console\controllers\BaseMigrateController::actionFresh()" does not exist in this Yii framework version.');
         }
 
-        $connection = $this->getConnection();
-
-        $collection = $connection->getCollection('hall_of_fame');
+        $collection = yii::$app->mongodb->getCollection('hall_of_fame');
         $collection->insert(['name' => 'Qiang Xue']);
         $collection->insert(['name' => 'Alexander Makarov']);
 
@@ -585,6 +577,6 @@ public function testRefreshMigration()
         $this->assertContains('Collection hall_of_fame dropped.', $result);
         $this->assertContains('No new migrations found. Your system is up-to-date.', $result);
 
-        $this->assertEmpty($connection->getDatabase()->listCollections(['name' => $collection->name]));
+        $this->assertEmpty(yii::$app->mongodb->getDatabase()->listCollections(['name' => $collection->name]));
     }
 }
\ No newline at end of file
diff --git a/tests/data/ar/ActiveRecord.php b/tests/data/ar/ActiveRecord.php
deleted file mode 100644
index 7229ea957..000000000
--- a/tests/data/ar/ActiveRecord.php
+++ /dev/null
@@ -1,20 +0,0 @@
-<?php
-
-namespace yiiunit\extensions\mongodb\data\ar;
-
-/**
- * Test Mongo ActiveRecord
- */
-class ActiveRecord extends \yii\mongodb\ActiveRecord
-{
-    public static $db;
-
-
-    /**
-     * {@inheritdoc}
-     */
-    public static function getDb()
-    {
-        return self::$db;
-    }
-}
diff --git a/tests/data/ar/Animal.php b/tests/data/ar/Animal.php
index 113d9b0b3..82b086eef 100644
--- a/tests/data/ar/Animal.php
+++ b/tests/data/ar/Animal.php
@@ -2,6 +2,8 @@
 
 namespace yiiunit\extensions\mongodb\data\ar;
 
+use yii\mongodb\ActiveRecord;
+
 /**
  * Animal
  *
diff --git a/tests/data/ar/Customer.php b/tests/data/ar/Customer.php
index 4eeda5f2e..28602ec23 100644
--- a/tests/data/ar/Customer.php
+++ b/tests/data/ar/Customer.php
@@ -3,6 +3,7 @@
 namespace yiiunit\extensions\mongodb\data\ar;
 
 use yiiunit\extensions\mongodb\data\ar\file\CustomerFile;
+use yii\mongodb\ActiveRecord;
 
 /**
  * @property \MongoDB\BSON\ObjectID|string $_id
diff --git a/tests/data/ar/CustomerOrder.php b/tests/data/ar/CustomerOrder.php
index 2d5a0724e..a3c24ea69 100644
--- a/tests/data/ar/CustomerOrder.php
+++ b/tests/data/ar/CustomerOrder.php
@@ -2,6 +2,8 @@
 
 namespace yiiunit\extensions\mongodb\data\ar;
 
+use yii\mongodb\ActiveRecord;
+
 /**
  * @property \MongoDB\BSON\ObjectID|string $_id
  * @property int $number
diff --git a/tests/data/ar/Dog.php b/tests/data/ar/Dog.php
index 2a9643baf..ac7bdd33b 100644
--- a/tests/data/ar/Dog.php
+++ b/tests/data/ar/Dog.php
@@ -2,6 +2,8 @@
 
 namespace yiiunit\extensions\mongodb\data\ar;
 
+use yii\mongodb\ActiveRecord;
+
 /**
  * Dog
  *
diff --git a/tests/data/ar/Item.php b/tests/data/ar/Item.php
index 396db0d35..af8df3443 100644
--- a/tests/data/ar/Item.php
+++ b/tests/data/ar/Item.php
@@ -2,6 +2,8 @@
 
 namespace yiiunit\extensions\mongodb\data\ar;
 
+use \yii\mongodb\ActiveRecord;
+
 /**
  * @property \MongoDB\BSON\ObjectID|string $_id
  * @property string $name
diff --git a/tests/data/ar/file/ActiveRecord.php b/tests/data/ar/file/ActiveRecord.php
deleted file mode 100644
index 8fe45f92d..000000000
--- a/tests/data/ar/file/ActiveRecord.php
+++ /dev/null
@@ -1,19 +0,0 @@
-<?php
-
-namespace yiiunit\extensions\mongodb\data\ar\file;
-
-/**
- * Test Mongo ActiveRecord
- */
-class ActiveRecord extends \yii\mongodb\file\ActiveRecord
-{
-    public static $db;
-
-    /**
-     * {@inheritdoc}
-     */
-    public static function getDb()
-    {
-        return self::$db;
-    }
-}
diff --git a/tests/data/ar/file/CustomerFile.php b/tests/data/ar/file/CustomerFile.php
index 52be57985..5081cba19 100644
--- a/tests/data/ar/file/CustomerFile.php
+++ b/tests/data/ar/file/CustomerFile.php
@@ -1,7 +1,8 @@
 <?php
-
 namespace yiiunit\extensions\mongodb\data\ar\file;
 
+use yii\mongodb\file\ActiveRecord;
+
 class CustomerFile extends ActiveRecord
 {
     /**
diff --git a/tests/file/ActiveRecordTest.php b/tests/file/ActiveRecordTest.php
index 1b9b6249e..00350467c 100644
--- a/tests/file/ActiveRecordTest.php
+++ b/tests/file/ActiveRecordTest.php
@@ -23,7 +23,6 @@ class ActiveRecordTest extends TestCase
     protected function setUp()
     {
         parent::setUp();
-        ActiveRecord::$db = $this->getConnection();
         $this->dropFileCollection(CustomerFile::collectionName());
         $this->setUpTestRows();
         $filePath = $this->getTestFilePath();
@@ -55,7 +54,7 @@ protected function getTestFilePath()
      */
     protected function setUpTestRows()
     {
-        $collection = $this->getConnection()->getFileCollection(CustomerFile::collectionName());
+        $collection = yii::$app->mongodb->getFileCollection(CustomerFile::collectionName());
         $rows = [];
         for ($i = 1; $i <= 10; $i++) {
             $record = [
diff --git a/tests/file/ActiveRelationTest.php b/tests/file/ActiveRelationTest.php
index 9c5eb47ed..4a2a279ca 100644
--- a/tests/file/ActiveRelationTest.php
+++ b/tests/file/ActiveRelationTest.php
@@ -5,6 +5,7 @@
 use yiiunit\extensions\mongodb\data\ar\Customer;
 use yiiunit\extensions\mongodb\data\ar\file\CustomerFile;
 use yiiunit\extensions\mongodb\TestCase;
+use yii;
 
 /**
  * @group file
@@ -14,8 +15,6 @@ class ActiveRelationTest extends TestCase
     protected function setUp()
     {
         parent::setUp();
-        \yiiunit\extensions\mongodb\data\ar\ActiveRecord::$db = $this->getConnection();
-        \yiiunit\extensions\mongodb\data\ar\file\ActiveRecord::$db = $this->getConnection();
         $this->setUpTestRows();
     }
 
@@ -31,7 +30,7 @@ protected function tearDown()
      */
     protected function setUpTestRows()
     {
-        $fileCollection = $this->getConnection()->getFileCollection(CustomerFile::collectionName());
+        $fileCollection = yii::$app->mongodb->getFileCollection(CustomerFile::collectionName());
         $customers = [];
         $files = [];
         for ($i = 1; $i <= 5; $i++) {
@@ -52,7 +51,7 @@ protected function setUpTestRows()
                 'file_id' => $file['_id'],
             ];
         }
-        $customerCollection = $this->getConnection()->getCollection(Customer::collectionName());
+        $customerCollection = yii::$app->mongodb->getCollection(Customer::collectionName());
         $customers = $customerCollection->batchInsert($customers);
     }
 
diff --git a/tests/file/CollectionTest.php b/tests/file/CollectionTest.php
index 07c4350d2..3fb263cff 100644
--- a/tests/file/CollectionTest.php
+++ b/tests/file/CollectionTest.php
@@ -3,6 +3,7 @@
 namespace yiiunit\extensions\mongodb\file;
 
 use MongoDB\BSON\ObjectID;
+use yii;
 use yii\mongodb\file\Cursor;
 use yii\mongodb\file\Download;
 use yiiunit\extensions\mongodb\TestCase;
@@ -22,7 +23,7 @@ protected function tearDown()
 
     public function testGetChunkCollection()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
         $chunkCollection = $collection->getChunkCollection();
         $this->assertTrue($chunkCollection instanceof \yii\mongodb\Collection);
         $this->assertTrue($chunkCollection->database instanceof \yii\mongodb\Database);
@@ -30,7 +31,7 @@ public function testGetChunkCollection()
 
     public function testGetFileCollection()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
         $fileCollection = $collection->getFileCollection();
         $this->assertTrue($fileCollection instanceof \yii\mongodb\Collection);
         $this->assertTrue($fileCollection->database instanceof \yii\mongodb\Database);
@@ -38,7 +39,7 @@ public function testGetFileCollection()
 
     public function testEnsureIndexes()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $collection->ensureIndexes();
         $this->assertCount(2, $collection->listIndexes());
@@ -54,14 +55,14 @@ public function testEnsureIndexes()
 
     public function testFind()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
         $cursor = $collection->find();
         $this->assertTrue($cursor instanceof Cursor);
     }
 
     public function testInsertFile()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $filename = __FILE__;
         $id = $collection->insertFile($filename);
@@ -77,7 +78,7 @@ public function testInsertFile()
 
     public function testInsertFileContent()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $bytes = 'Test file content';
         $id = $collection->insertFileContent($bytes);
@@ -97,7 +98,7 @@ public function testInsertFileContent()
      */
     public function testGet()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $bytes = 'Test file content';
         $id = $collection->insertFileContent($bytes);
@@ -112,7 +113,7 @@ public function testGet()
      */
     public function testDeleteFile()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $bytes = 'Test file content';
         $id = $collection->insertFileContent($bytes);
@@ -128,7 +129,7 @@ public function testDeleteFile()
      */
     public function testRemove()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         for ($i = 1; $i <=10; $i++) {
             $bytes = 'Test file content ' . $i;
diff --git a/tests/file/DownloadTest.php b/tests/file/DownloadTest.php
index 0fb3dd037..512743e02 100644
--- a/tests/file/DownloadTest.php
+++ b/tests/file/DownloadTest.php
@@ -3,7 +3,7 @@
 namespace yiiunit\extensions\mongodb\file;
 
 use yiiunit\extensions\mongodb\TestCase;
-
+use yii;
 /**
  * @group file
  */
@@ -19,7 +19,7 @@ protected function tearDown()
 
     public function testToStream()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $upload = $collection->createUpload();
         $document = $upload->addContent('test content')->complete();
@@ -34,7 +34,7 @@ public function testToStream()
 
     public function testToFile()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $upload = $collection->createUpload();
         $document = $upload->addContent('test content')->complete();
@@ -49,7 +49,7 @@ public function testToFile()
 
     public function testSubstr()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $upload = $collection->createUpload();
         $upload->chunkSize = 10;
diff --git a/tests/file/QueryTest.php b/tests/file/QueryTest.php
index 46b2a564c..b622cde4a 100644
--- a/tests/file/QueryTest.php
+++ b/tests/file/QueryTest.php
@@ -2,6 +2,7 @@
 
 namespace yiiunit\extensions\mongodb\file;
 
+use yii;
 use yii\mongodb\file\Download;
 use yii\mongodb\file\Query;
 use yiiunit\extensions\mongodb\TestCase;
@@ -28,7 +29,7 @@ protected function tearDown()
      */
     protected function setUpTestRows()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
         for ($i = 1; $i <= 10; $i++) {
             $collection->insertFileContent('content' . $i, [
                 'filename' => 'name' . $i,
@@ -41,28 +42,25 @@ protected function setUpTestRows()
 
     public function testAll()
     {
-        $connection = $this->getConnection();
         $query = new Query();
-        $rows = $query->from('fs')->all($connection);
+        $rows = $query->from('fs')->all();
         $this->assertEquals(10, count($rows));
     }
 
     public function testOne()
     {
-        $connection = $this->getConnection();
         $query = new Query();
-        $row = $query->from('fs')->one($connection);
+        $row = $query->from('fs')->one();
         $this->assertTrue(is_array($row));
         $this->assertTrue($row['file'] instanceof Download);
     }
 
     public function testDirectMatch()
     {
-        $connection = $this->getConnection();
         $query = new Query();
         $rows = $query->from('fs')
             ->where(['file_index' => 5])
-            ->all($connection);
+            ->all();
         $this->assertEquals(1, count($rows));
 
         $file = $rows[0];
diff --git a/tests/file/StreamWrapperTest.php b/tests/file/StreamWrapperTest.php
index ac82c14dc..8269079cf 100644
--- a/tests/file/StreamWrapperTest.php
+++ b/tests/file/StreamWrapperTest.php
@@ -2,15 +2,15 @@
 
 namespace yiiunit\extensions\mongodb\file;
 
+use yii;
 use yiiunit\extensions\mongodb\TestCase;
 
 class StreamWrapperTest extends TestCase
 {
     protected function tearDown()
     {
-        $connection = $this->getConnection();
-        if (in_array($connection->fileStreamProtocol, stream_get_wrappers())) {
-            stream_wrapper_unregister($connection->fileStreamProtocol);
+        if (in_array(yii::$app->mongodb->fileStreamProtocol, stream_get_wrappers())) {
+            stream_wrapper_unregister(yii::$app->mongodb->fileStreamProtocol);
         }
 
         $this->dropFileCollection('fs');
@@ -22,7 +22,7 @@ protected function tearDown()
 
     public function testCreateFromDownload()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $upload = $collection->createUpload();
         $document = $upload->addContent('test content')->complete();
@@ -36,15 +36,8 @@ public function testCreateFromDownload()
 
     public function testWriteResource()
     {
-        $connection = $this->getConnection();
-        $this->mockApplication([
-            'components' => [
-                'mongodb' => $connection
-            ],
-        ]);
-
-        $connection->registerFileStreamWrapper(true);
-        $databaseName = $connection->getDefaultDatabaseName();
+        yii::$app->mongodb->registerFileStreamWrapper(true);
+        $databaseName = yii::$app->mongodb->getDefaultDatabaseName();
 
         $url = "gridfs://{$databaseName}.fs?filename=test.txt";
         $resource = fopen($url, 'w');
@@ -52,7 +45,7 @@ public function testWriteResource()
         fwrite($resource, 'end');
         fclose($resource);
 
-        $collection = $connection->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
         $document = $collection->findOne(['filename' => 'test.txt']);
         $this->assertNotEmpty($document);
 
@@ -61,19 +54,12 @@ public function testWriteResource()
 
     public function testReadResource()
     {
-        $connection = $this->getConnection();
-        $this->mockApplication([
-            'components' => [
-                'mongodb' => $connection
-            ],
-        ]);
-
-        $collection = $connection->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
         $upload = $collection->createUpload();
         $document = $upload->addContent('test content')->complete();
 
-        $connection->registerFileStreamWrapper(true);
-        $databaseName = $connection->getDefaultDatabaseName();
+        yii::$app->mongodb->registerFileStreamWrapper(true);
+        $databaseName = yii::$app->mongodb->getDefaultDatabaseName();
 
         $url = "gridfs://{$databaseName}.fs?_id=" . $document['_id'];
         $resource = fopen($url, 'r');
@@ -83,15 +69,8 @@ public function testReadResource()
     
     public function testSeek()
     {
-        $connection = $this->getConnection();
-        $this->mockApplication([
-            'components' => [
-                'mongodb' => $connection
-            ],
-        ]);
-
-        $connection->registerFileStreamWrapper(true);
-        $databaseName = $connection->getDefaultDatabaseName();
+        yii::$app->mongodb->registerFileStreamWrapper(true);
+        $databaseName = yii::$app->mongodb->getDefaultDatabaseName();
 
         $url = "gridfs://{$databaseName}.fs?filename=test.txt";
         $resource = fopen($url, 'w');
diff --git a/tests/file/UploadTest.php b/tests/file/UploadTest.php
index 95983d4e8..56c76bad9 100644
--- a/tests/file/UploadTest.php
+++ b/tests/file/UploadTest.php
@@ -3,6 +3,7 @@
 namespace yiiunit\extensions\mongodb\file;
 
 use MongoDB\BSON\ObjectID;
+use yii;
 use yiiunit\extensions\mongodb\TestCase;
 
 /**
@@ -20,7 +21,7 @@ protected function tearDown()
 
     public function testAddContent()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $upload = $collection->createUpload();
         $document = $upload->addContent('content line 1')
@@ -37,7 +38,7 @@ public function testAddContent()
      */
     public function testAddContentChunk()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $upload = $collection->createUpload();
         $upload->chunkSize = 10;
@@ -50,7 +51,7 @@ public function testAddContentChunk()
 
     public function testAddStream()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $upload = $collection->createUpload();
 
@@ -68,7 +69,7 @@ public function testAddStream()
      */
     public function testCancel()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $upload = $collection->createUpload();
         $document = $upload->addContent('content line 1');
@@ -85,7 +86,7 @@ public function testCancel()
      */
     public function testCustomId()
     {
-        $collection = $this->getConnection()->getFileCollection();
+        $collection = yii::$app->mongodb->getFileCollection();
 
         $id = new ObjectID();
         $upload = $collection->createUpload([
diff --git a/tests/i18n/MongoDbMessageSourceTest.php b/tests/i18n/MongoDbMessageSourceTest.php
index d2f7273a9..33667745b 100644
--- a/tests/i18n/MongoDbMessageSourceTest.php
+++ b/tests/i18n/MongoDbMessageSourceTest.php
@@ -2,6 +2,7 @@
 
 namespace yiiunit\extensions\mongodb\i18n;
 
+use yii;
 use yii\i18n\I18N;
 use yii\mongodb\i18n\MongoDbMessageSource;
 use yiiunit\extensions\mongodb\TestCase;
@@ -33,8 +34,7 @@ protected function tearDown()
      */
     protected function setupTestRows()
     {
-        $db = $this->getConnection();
-        $collection = $db->getCollection('message');
+        $collection = yii::$app->mongodb->getCollection('message');
         $collection->batchInsert([
             [
                 'language' => 'de',
@@ -104,7 +104,6 @@ protected function setupI18N()
         $this->i18n = new I18N([
             'translations' => [
                 '*' => new MongoDbMessageSource([
-                    'db' => $this->getConnection(),
                     'sourceLanguage' => 'en-US',
                 ])
             ]
diff --git a/tests/log/MongoDbTargetTest.php b/tests/log/MongoDbTargetTest.php
index 2c9847f19..7335bcffa 100644
--- a/tests/log/MongoDbTargetTest.php
+++ b/tests/log/MongoDbTargetTest.php
@@ -14,21 +14,11 @@ protected function tearDown()
         parent::tearDown();
     }
 
-    /**
-     * @return MongoDbTarget test log target
-     */
-    protected function createLogTarget()
-    {
-        return new MongoDbTarget([
-            'db' => $this->getConnection(),
-        ]);
-    }
-
     // Tests :
 
     public function testExport()
     {
-        $target = $this->createLogTarget();
+        $target = new MongoDbTarget();
 
         $target->messages = [
             [
diff --git a/tests/rbac/MongoDbManagerTest.php b/tests/rbac/MongoDbManagerTest.php
index 5800aef55..16510ab70 100644
--- a/tests/rbac/MongoDbManagerTest.php
+++ b/tests/rbac/MongoDbManagerTest.php
@@ -23,7 +23,7 @@ class MongoDbManagerTest extends TestCase
     protected function setUp()
     {
         parent::setUp();
-        $this->auth = $this->createManager();
+        $this->auth = new MongoDbManager();
     }
 
     protected function tearDown()
@@ -34,14 +34,6 @@ protected function tearDown()
         parent::tearDown();
     }
 
-    /**
-     * @return MongoDbManager
-     */
-    protected function createManager()
-    {
-        return new MongoDbManager(['db' => $this->getConnection()]);
-    }
-
     // Tests :
 
     public function testCreateRole()
@@ -354,7 +346,7 @@ public function testAssignMultipleRoles()
         $this->auth->assign($reader, 'readingAuthor');
         $this->auth->assign($author, 'readingAuthor');
 
-        $this->auth = $this->createManager();
+        $this->auth = new MongoDbManager();
 
         $roles = $this->auth->getRolesByUser('readingAuthor');
         $roleNames = [];
@@ -376,7 +368,7 @@ public function testAssignmentsToIntegerId()
         $this->auth->assign($author, 1337);
         $this->auth->assign($reader, 1337);
 
-        $this->auth = $this->createManager();
+        $this->auth = new MongoDbManager();
 
         $this->assertEquals(0, count($this->auth->getAssignments(0)));
         $this->assertEquals(1, count($this->auth->getAssignments(42)));
@@ -389,7 +381,7 @@ public function testGetAssignmentsByRole()
         $reader = $this->auth->getRole('reader');
         $this->auth->assign($reader, 123);
 
-        $this->auth = $this->createManager();
+        $this->auth = new MongoDbManager();
 
         $this->assertEquals([], $this->auth->getUserIdsByRole('nonexisting'));
         $this->assertEquals(['reader A', '123'], $this->auth->getUserIdsByRole('reader'), '', 0.0, 10, true);
diff --git a/tests/validators/MongoDateValidatorTest.php b/tests/validators/MongoDateValidatorTest.php
index 32faf0efe..bb89195a8 100644
--- a/tests/validators/MongoDateValidatorTest.php
+++ b/tests/validators/MongoDateValidatorTest.php
@@ -12,7 +12,6 @@ class MongoDateValidatorTest extends TestCase
     protected function setUp()
     {
         parent::setUp();
-        $this->mockApplication();
         date_default_timezone_set('UTC');
     }
 
diff --git a/tests/validators/MongoIdValidatorTest.php b/tests/validators/MongoIdValidatorTest.php
index 6c8208163..e066fb2f6 100644
--- a/tests/validators/MongoIdValidatorTest.php
+++ b/tests/validators/MongoIdValidatorTest.php
@@ -9,12 +9,6 @@
 
 class MongoIdValidatorTest extends TestCase
 {
-    protected function setUp()
-    {
-        parent::setUp();
-        $this->mockApplication();
-    }
-
     public function testValidateValue()
     {
         $validator = new MongoIdValidator();