diff --git a/Normalizer/DenormalizerInterface.php b/Normalizer/DenormalizerInterface.php
index 54e41431e0ce..7a12d20f1132 100644
--- a/Normalizer/DenormalizerInterface.php
+++ b/Normalizer/DenormalizerInterface.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\Serializer\Normalizer;
 
 use Symfony\Component\Serializer\Exception\BadMethodCallException;
+use Symfony\Component\Serializer\Exception\ExceptionInterface;
 use Symfony\Component\Serializer\Exception\ExtraAttributesException;
 use Symfony\Component\Serializer\Exception\InvalidArgumentException;
 use Symfony\Component\Serializer\Exception\LogicException;
@@ -41,6 +42,7 @@ interface DenormalizerInterface
      * @throws ExtraAttributesException Occurs when the item doesn't have attribute to receive given data
      * @throws LogicException           Occurs when the normalizer is not supposed to denormalize
      * @throws RuntimeException         Occurs if the class cannot be instantiated
+     * @throws ExceptionInterface       Occurs for all the other cases of errors
      */
     public function denormalize($data, $class, $format = null, array $context = []);
 
diff --git a/Normalizer/NormalizerInterface.php b/Normalizer/NormalizerInterface.php
index 09aca60ff23e..02a211858492 100644
--- a/Normalizer/NormalizerInterface.php
+++ b/Normalizer/NormalizerInterface.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\Serializer\Normalizer;
 
 use Symfony\Component\Serializer\Exception\CircularReferenceException;
+use Symfony\Component\Serializer\Exception\ExceptionInterface;
 use Symfony\Component\Serializer\Exception\InvalidArgumentException;
 use Symfony\Component\Serializer\Exception\LogicException;
 
@@ -35,6 +36,7 @@ interface NormalizerInterface
      * @throws CircularReferenceException Occurs when the normalizer detects a circular reference when no circular
      *                                    reference handler can fix it
      * @throws LogicException             Occurs when the normalizer is not called in an expected context
+     * @throws ExceptionInterface         Occurs for all the other cases of errors
      */
     public function normalize($object, $format = null, array $context = []);
 
diff --git a/Tests/Mapping/ClassMetadataTest.php b/Tests/Mapping/ClassMetadataTest.php
index f62967935dc5..636d8a8ab891 100644
--- a/Tests/Mapping/ClassMetadataTest.php
+++ b/Tests/Mapping/ClassMetadataTest.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\Serializer\Tests\Mapping;
 
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\Serializer\Mapping\AttributeMetadata;
 use Symfony\Component\Serializer\Mapping\ClassMetadata;
 
 /**
@@ -29,11 +30,8 @@ public function testAttributeMetadata()
     {
         $classMetadata = new ClassMetadata('c');
 
-        $a1 = $this->getMockBuilder('Symfony\Component\Serializer\Mapping\AttributeMetadataInterface')->getMock();
-        $a1->method('getName')->willReturn('a1');
-
-        $a2 = $this->getMockBuilder('Symfony\Component\Serializer\Mapping\AttributeMetadataInterface')->getMock();
-        $a2->method('getName')->willReturn('a2');
+        $a1 = new AttributeMetadata('a1');
+        $a2 = new AttributeMetadata('a2');
 
         $classMetadata->addAttributeMetadata($a1);
         $classMetadata->addAttributeMetadata($a2);
@@ -46,33 +44,28 @@ public function testMerge()
         $classMetadata1 = new ClassMetadata('c1');
         $classMetadata2 = new ClassMetadata('c2');
 
-        $ac1 = $this->getMockBuilder('Symfony\Component\Serializer\Mapping\AttributeMetadataInterface')->getMock();
-        $ac1->method('getName')->willReturn('a1');
-        $ac1->method('getGroups')->willReturn(['a', 'b']);
-
-        $ac2 = $this->getMockBuilder('Symfony\Component\Serializer\Mapping\AttributeMetadataInterface')->getMock();
-        $ac2->method('getName')->willReturn('a1');
-        $ac2->method('getGroups')->willReturn(['b', 'c']);
+        $ac1 = new AttributeMetadata('a1');
+        $ac1->addGroup('a');
+        $ac1->addGroup('b');
+        $ac2 = new AttributeMetadata('a1');
+        $ac2->addGroup('b');
+        $ac2->addGroup('c');
 
         $classMetadata1->addAttributeMetadata($ac1);
         $classMetadata2->addAttributeMetadata($ac2);
 
         $classMetadata1->merge($classMetadata2);
 
-        $ac1->method('getGroups')->willReturn('a', 'b', 'c');
-
-        $this->assertEquals(['a1' => $ac1], $classMetadata2->getAttributesMetadata());
+        $this->assertSame(['a', 'b', 'c'], $ac1->getGroups());
+        $this->assertEquals(['a1' => $ac1], $classMetadata1->getAttributesMetadata());
     }
 
     public function testSerialize()
     {
         $classMetadata = new ClassMetadata('a');
 
-        $a1 = $this->getMockBuilder('Symfony\Component\Serializer\Mapping\AttributeMetadataInterface')->getMock();
-        $a1->method('getName')->willReturn('b1');
-
-        $a2 = $this->getMockBuilder('Symfony\Component\Serializer\Mapping\AttributeMetadataInterface')->getMock();
-        $a2->method('getName')->willReturn('b2');
+        $a1 = new AttributeMetadata('b1');
+        $a2 = new AttributeMetadata('b2');
 
         $classMetadata->addAttributeMetadata($a1);
         $classMetadata->addAttributeMetadata($a2);