Added ontime validator picks

src/Vouchers/Bag.php

@@ -57,11 +57,34 @@ public function fill($number = 0)
      *
      * @return Voucher $voucher
      */
-    public function pick()
+    public function pick(callable $callback = null)
     {
+        if ($callback) {
+            return $this->pickWithCallback($callback);
+        }
+
         return $this->values[array_rand($this->values)];
     }
 
+    /**
+     * Receive a callback and use it to pick
+     * a voucher.
+     *
+     * @param callable $callback
+     * @throws NoValidVouchers
+     * @return Voucher $voucher
+     */
+    public function pickWithCallback(callable $callback)
+    {
+        foreach ($this->values as $voucher) {
+            if ($callback($voucher)) {
+                return $voucher;
+            }
+        }
+
+        throw new \Vouchers\Exceptions\NoValidVouchers();
+    }
+
     /**
      * Add an array to our collection.
      *

tests/Vouchers/BagTest.php

@@ -206,4 +206,44 @@ public function testFindAVoucher()
         $test = $bag->find("MY-VOUCHER");
         $this->assertSame($voucher, $test);
     }
+
+    /**
+     * Test pick with callback.
+     */
+    public function testPickWithACallback()
+    {
+        $bag = new \Vouchers\Bag();
+        $voucher = new \Vouchers\Voucher([
+            'code'  => 'MY-Test-code',
+            'owner' => 'tester'
+        ]);
+        $bag->add($voucher);
+
+        $test = $bag->pick(function ($voucher) {
+            return $voucher->get('owner') == "tester";
+        });
+
+        $this->assertSame($test, $voucher);
+    }
+
+    /**
+     * Test pick with callback.
+     *
+     * @expectedException \Vouchers\Exceptions\NoValidVouchers
+     */
+    public function testPickWithACallbackFails()
+    {
+        $bag = new \Vouchers\Bag();
+        $voucher = new \Vouchers\Voucher([
+            'code'  => 'MY-Test-code',
+            'owner' => 'tester'
+        ]);
+        $bag->add($voucher);
+
+        $test = $bag->pick(function ($voucher) {
+            return $voucher->get('owner') == "not a tester";
+        });
+
+        $this->assertSame($test, $voucher);
+    }
 }