bug symfony#18732 [PropertyAccess][DX] Enhance exception that say that some methods are missing if they don't (nykopol)

This PR was squashed before being merged into the 2.7 branch (closes symfony#18732).

Discussion
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[PropertyAccess][DX] Enhance exception that say that some methods are missing if they don't

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#18694
| License       | MIT
| Doc PR        |

When you try do define a manyToMany association but you don't give an array or \Traversable, the raised exception say that some methods are missing while they don't. This PR check if the adder and setter methods exists and if so, give a exception that pointing on the real problem.

Commits
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c46519b [PropertyAccess][DX] Enhance exception that say that some methods are missing if they don't

Author: fabpot

src/Symfony/Component/PropertyAccess/PropertyAccessor.php

@@ -714,6 +714,17 @@ private function getWriteAccessInfo($class, $property, $value)
                     // we call the getter and hope the __call do the job
                     $access[self::ACCESS_TYPE] = self::ACCESS_TYPE_MAGIC;
                     $access[self::ACCESS_NAME] = $setter;
+                } elseif (null !== $methods = $this->findAdderAndRemover($reflClass, $singulars)) {
+                    $access[self::ACCESS_TYPE] = self::ACCESS_TYPE_NOT_FOUND;
+                    $access[self::ACCESS_NAME] = sprintf(
+                        'The property "%s" in class "%s" can be defined with the methods "%s()" but '.
+                        'the new value must be an array or an instance of \Traversable, '.
+                        '"%s" given.',
+                        $property,
+                        $reflClass->name,
+                        implode('()", "', $methods),
+                        is_object($value) ? get_class($value) : gettype($value)
+                    );
                 } else {
                     $access[self::ACCESS_TYPE] = self::ACCESS_TYPE_NOT_FOUND;
                     $access[self::ACCESS_NAME] = sprintf(

src/Symfony/Component/PropertyAccess/Tests/PropertyAccessorCollectionTest.php

@@ -194,4 +194,15 @@ public function testIsWritableReturnsFalseIfNoAdderNorRemoverExists()
 
         $this->assertFalse($this->propertyAccessor->isWritable($car, 'axes', $axes));
     }
+
+    /**
+     * @expectedException \Symfony\Component\PropertyAccess\Exception\NoSuchPropertyException
+     * expectedExceptionMessageRegExp /The property "axes" in class "Mock_PropertyAccessorCollectionTest_Car[^"]*" can be defined with the methods "addAxis()", "removeAxis()" but the new value must be an array or an instance of \Traversable, "string" given./
+     */
+    public function testSetValueFailsIfAdderAndRemoverExistButValueIsNotTraversable()
+    {
+        $car = $this->getMock(__CLASS__.'_Car');
+
+        $this->propertyAccessor->setValue($car, 'axes', 'Not an array or Traversable');
+    }
 }