diff --git a/lib/internal/Magento/Framework/Reflection/Test/Unit/MethodsMapTest.php b/lib/internal/Magento/Framework/Reflection/Test/Unit/MethodsMapTest.php
index 35af774c7ba45fba1b49f52cb2779602f2deb8fd..67a372c4d33ca754d7d35e9005730c55a55e4a19 100644
--- a/lib/internal/Magento/Framework/Reflection/Test/Unit/MethodsMapTest.php
+++ b/lib/internal/Magento/Framework/Reflection/Test/Unit/MethodsMapTest.php
@@ -86,44 +86,46 @@ class MethodsMapTest extends \PHPUnit_Framework_TestCase
 
     public function testGetMethodsMap()
     {
+        $data = [
+            'getMethodReturnType' => [
+                'type' => 'string',
+                'isRequired' => true,
+                'description' => null,
+                'parameterCount' => 2,
+            ],
+            'getMethodsMap' => [
+                'type' => 'array',
+                'isRequired' => true,
+                'description' => "<pre> Service methods' reflection data stored in cache as 'methodName' => "
+                    . "'returnType' ex. [ 'create' => '\Magento\Customer\Api\Data\Customer', 'validatePassword' "
+                    . "=> 'boolean' ] </pre>",
+                'parameterCount' => 1,
+            ],
+            'getMethodParams' => [
+                'type' => 'array',
+                'isRequired' => true,
+                'description' => null,
+                'parameterCount' => 2
+            ],
+            'isMethodValidForDataField' => [
+                'type' => 'bool',
+                'isRequired' => true,
+                'description' => null,
+                'parameterCount' => 2,
+            ],
+            'isMethodReturnValueRequired' => [
+                'type' => 'bool',
+                'isRequired' => true,
+                'description' => null,
+                'parameterCount' => 2,
+            ],
+        ];
         $this->serializerMock->expects($this->once())
-            ->method('serialize');
+            ->method('serialize')
+            ->with($data);
         $methodsMap = $this->object->getMethodsMap(\Magento\Framework\Reflection\MethodsMap::class);
         $this->assertEquals(
-            [
-                'getMethodReturnType' => [
-                    'type' => 'string',
-                    'isRequired' => true,
-                    'description' => null,
-                    'parameterCount' => 2,
-                ],
-                'getMethodsMap' => [
-                    'type' => 'array',
-                    'isRequired' => true,
-                    'description' => "<pre> Service methods' reflection data stored in cache as 'methodName' => "
-                        . "'returnType' ex. [ 'create' => '\Magento\Customer\Api\Data\Customer', 'validatePassword' "
-                        . "=> 'boolean' ] </pre>",
-                    'parameterCount' => 1,
-                ],
-                'getMethodParams' => [
-                    'type' => 'array',
-                    'isRequired' => true,
-                    'description' => null,
-                    'parameterCount' => 2
-                ],
-                'isMethodValidForDataField' => [
-                    'type' => 'bool',
-                    'isRequired' => true,
-                    'description' => null,
-                    'parameterCount' => 2,
-                ],
-                'isMethodReturnValueRequired' => [
-                    'type' => 'bool',
-                    'isRequired' => true,
-                    'description' => null,
-                    'parameterCount' => 2,
-                ],
-            ],
+            $data,
             $methodsMap
         );
     }
diff --git a/lib/internal/Magento/Framework/Webapi/Test/Unit/ServiceInputProcessorTest.php b/lib/internal/Magento/Framework/Webapi/Test/Unit/ServiceInputProcessorTest.php
index 4892c96a220580d2a678c3ce69f3f75752bab8ef..658755d38a4e86ea8ffcc4e8333e30e4f6507658 100644
--- a/lib/internal/Magento/Framework/Webapi/Test/Unit/ServiceInputProcessorTest.php
+++ b/lib/internal/Magento/Framework/Webapi/Test/Unit/ServiceInputProcessorTest.php
@@ -100,13 +100,9 @@ class ServiceInputProcessorTest extends \PHPUnit_Framework_TestCase
         );
         $serializerMock = $this->getMock(SerializerInterface::class);
         $serializerMock->method('serialize')
-            ->willReturnCallback(function ($data) {
-                return json_encode($data);
-            });
+            ->willReturn('serializedData');
         $serializerMock->method('unserialize')
-            ->willReturnCallback(function ($string) {
-                return json_decode($string, true);
-            });
+            ->willReturn('unserializedData');
         $objectManager->setBackwardCompatibleProperty(
             $this->methodsMap,
             'serializer',