Warning added if defaultProps were defined as an instance property (#9433)

* Added warning when defaultProps was defined as an instance property

* Added testcases to check warning message for defaultProps

* Update fiber tests

scripts/fiber/tests-passing.txt

@@ -461,6 +461,7 @@ src/renderers/__tests__/ReactCompositeComponent-test.js
 * should call componentWillUnmount before unmounting
 * should warn when shouldComponentUpdate() returns undefined
 * should warn when componentDidUnmount method is defined
+* should warn when defaultProps was defined as an instance property
 * should pass context to children when not owner
 * should skip update when rerendering element in container
 * should pass context when re-rendered for static child

src/renderers/__tests__/ReactCompositeComponent-test.js

@@ -488,6 +488,29 @@ describe('ReactCompositeComponent', () => {
     );
   });
 
+  it('should warn when defaultProps was defined as an instance property', () => {
+    spyOn(console, 'error');
+
+    class Component extends React.Component {
+      constructor(props) {
+        super(props);
+        this.defaultProps = {name: 'Abhay'};
+      }
+
+      render() {
+        return <div />;
+      }
+    }
+
+    ReactTestUtils.renderIntoDocument(<Component />);
+
+    expectDev(console.error.calls.count()).toBe(1);
+    expectDev(console.error.calls.argsFor(0)[0]).toBe(
+      'Warning: defaultProps was defined as an instance property ' +
+        'on Component. Use a static property to define defaultProps instead.',
+    );
+  });
+
   it('should pass context to children when not owner', () => {
     class Parent extends React.Component {
       render() {

src/renderers/shared/fiber/ReactFiberClassComponent.js

@@ -228,6 +228,13 @@ module.exports = function(
         name,
         name,
       );
+      const noInstanceDefaultProps = !instance.defaultProps;
+      warning(
+        noInstanceDefaultProps,
+        'defaultProps was defined as an instance property on %s. Use a static ' +
+          'property to define defaultProps instead.',
+        name,
+      );
     }
 
     const state = instance.state;

src/renderers/shared/stack/reconciler/ReactCompositeComponent.js

@@ -299,6 +299,12 @@ var ReactCompositeComponent = {
           'componentWillRecieveProps(). Did you mean componentWillReceiveProps()?',
         this.getName() || 'A component',
       );
+      warning(
+        !inst.defaultProps,
+        'defaultProps was defined as an instance property on %s. Use a static ' +
+          'property to define defaultProps instead.',
+        this.getName() || 'a component',
+      );
     }
 
     var initialState = inst.state;