Add unit test for http client factory

test/Unit/Http/PrismicHttpClientFactoryTest.php

@@ -0,0 +1,53 @@
+<?php
+declare(strict_types=1);
+
+namespace PrimoTest\Unit\Http;
+
+use PHPUnit\Framework\MockObject\MockObject;
+use Primo\Http\PrismicHttpClientFactory;
+use PrimoTest\Unit\TestCase;
+use Psr\Container\ContainerInterface;
+use Psr\Http\Client\ClientInterface;
+
+class PrismicHttpClientFactoryTest extends TestCase
+{
+    /** @var MockObject|ClientInterface */
+    private $container;
+
+    protected function setUp() : void
+    {
+        parent::setUp();
+        $this->container = $this->createMock(ContainerInterface::class);
+    }
+
+    private function clientInContainer(bool $value) : void
+    {
+        $this->container->expects($this->once())
+            ->method('has')
+            ->with(ClientInterface::class)
+            ->willReturn($value);
+    }
+
+    public function testThatClientInContainerWillBeReturnedWhenAvailable() : void
+    {
+        $client = $this->createMock(ClientInterface::class);
+        $this->clientInContainer(true);
+
+        $this->container->expects($this->once())
+            ->method('get')
+            ->with(ClientInterface::class)
+            ->willReturn($client);
+
+        $factory = new PrismicHttpClientFactory();
+        $this->assertSame($client, $factory($this->container));
+    }
+
+    public function testThatClientDiscoveryWillBeUsedWhenNoClientIsInTheContainer() : void
+    {
+        $this->clientInContainer(false);
+        $this->container->expects($this->never())->method('get');
+        $factory = new PrismicHttpClientFactory();
+        $factory($this->container);
+        $this->addToAssertionCount(1);
+    }
+}