Don't run checks which assume a defined instance against undefined

Validation tests for an undefined instance should be limited to those
tests which are actually applicable (e.g. required, default). Tests
which assume an instance previously attempted to validate an internal
default when the instance is undefined, rather than ignoring it, which
is incorrect behavior.

Closes #566.

Author: erayd

src/JsonSchema/Constraints/UndefinedConstraint.php

@@ -153,6 +153,12 @@ protected function validateCommonProperties(&$value, $schema = null, JsonPointer
                     $propertyName = end($propertyPaths);
                     $this->addError(ConstraintError::REQUIRED(), $path, array('property' => $propertyName));
                 }
+            } else {
+                // If the value is both undefined and not required, skip remaining checks
+                // in this method which assume an actual, defined instance when validating.
+                if ($value instanceof self) {
+                    return;
+                }
             }
         }
 

tests/Constraints/NotTest.php

@@ -31,6 +31,20 @@ public function getInvalidTests()
                         }
                     }
                 }'
+            ),
+            array( // check that a missing, required property is correctly validated
+                '{"y": "foo"}',
+                '{
+                    "type": "object",
+                    "required": ["x"],
+                    "properties": {
+                        "x": {
+                            "not": {
+                                "type": "null"
+                            }
+                        }
+                    }
+                }'
             )
         );
     }
@@ -69,6 +83,19 @@ public function getValidTests()
                         }
                     }
                 }'
+            ),
+            array( // check that a missing, non-required property isn't validated
+                '{"y": "foo"}',
+                '{
+                    "type": "object",
+                    "properties": {
+                        "x": {
+                            "not": {
+                                "type": "null"
+                            }
+                        }
+                    }
+                }'
             )
         );
     }