Add late class validation warnings for statics

ES6 classes won't have an early validation step. Therefore I added some
extra validation later on in the process. These would've normally have
been caught by createClass in classic React.

src/classic/class/ReactClass.js

@@ -868,6 +868,12 @@ var ReactClass = {
     // Initialize the defaultProps property after all mixins have been merged
     if (Constructor.getDefaultProps) {
       Constructor.defaultProps = Constructor.getDefaultProps();
+      if (__DEV__) {
+        // This is a tag to indicate that this use of getDefaultProps is ok,
+        // since it's used with createClass. If it's not, then it's likely a
+        // mistake so we'll warn you to use the static property instead.
+        Constructor.getDefaultProps._isReactClassApproved = true;
+      }
     }
 
     invariant(

src/classic/element/ReactElementValidator.js

@@ -20,10 +20,12 @@
 
 var ReactElement = require('ReactElement');
 var ReactPropTypeLocations = require('ReactPropTypeLocations');
+var ReactPropTypeLocationNames = require('ReactPropTypeLocationNames');
 var ReactCurrentOwner = require('ReactCurrentOwner');
 
 var getIteratorFn = require('getIteratorFn');
 var monitorCodeUse = require('monitorCodeUse');
+var invariant = require('invariant');
 var warning = require('warning');
 
 /**
@@ -236,6 +238,16 @@ function checkPropTypes(componentName, propTypes, props, location) {
       // fail the render phase where it didn't fail before. So we log it.
       // After these have been cleaned up, we'll let them throw.
       try {
+        // This is intentionally an invariant that gets caught. It's the same
+        // behavior as without this statement except with a better message.
+        invariant(
+          typeof propTypes[propName] === 'function',
+          '%s: %s type `%s` is invalid; it must be a function, usually from ' +
+          'React.PropTypes.',
+          componentName || 'React class',
+          ReactPropTypeLocationNames[location],
+          propName
+        );
         error = propTypes[propName](props, propName, componentName, location);
       } catch (ex) {
         error = ex;
@@ -296,7 +308,15 @@ var ReactElementValidator = {
           ReactPropTypeLocations.context
         );
       }
+      if (typeof type.getDefaultProps === 'function') {
+        warning(
+          type.getDefaultProps._isReactClassApproved,
+          'getDefaultProps is only used on classic React.createClass ' +
+          'definitions. Use a static property named `defaultProps` instead.'
+        );
+      }
     }
+
     return element;
   },
 

src/core/ReactCompositeComponent.js

@@ -19,6 +19,7 @@ var ReactElement = require('ReactElement');
 var ReactInstanceMap = require('ReactInstanceMap');
 var ReactPerf = require('ReactPerf');
 var ReactPropTypeLocations = require('ReactPropTypeLocations');
+var ReactPropTypeLocationNames = require('ReactPropTypeLocationNames');
 var ReactUpdates = require('ReactUpdates');
 
 var assign = require('Object.assign');
@@ -515,8 +516,22 @@ var ReactCompositeComponentMixin = assign({},
                         this._instance.constructor.name;
     for (var propName in propTypes) {
       if (propTypes.hasOwnProperty(propName)) {
-        var error =
-          propTypes[propName](props, propName, componentName, location);
+        var error;
+        try {
+          // This is intentionally an invariant that gets caught. It's the same
+          // behavior as without this statement except with a better message.
+          invariant(
+            typeof propTypes[propName] === 'function',
+            '%s: %s type `%s` is invalid; it must be a function, usually ' +
+            'from React.PropTypes.',
+            componentName || 'React class',
+            ReactPropTypeLocationNames[location],
+            propName
+          );
+          error = propTypes[propName](props, propName, componentName, location);
+        } catch (ex) {
+          error = ex;
+        }
         if (error instanceof Error) {
           // We may want to extend this logic for similar errors in
           // React.render calls, so I'm abstracting it away into

src/modern/element/__tests__/ReactJSXElementValidator-test.js

@@ -290,4 +290,62 @@ describe('ReactJSXElementValidator', function() {
     expect(console.warn.calls.length).toBe(2);
   });
 
+  it('should warn on invalid prop types', function() {
+    // Since there is no prevalidation step for ES6 classes, there is no hook
+    // for us to issue a warning earlier than element creation when the error
+    // actually occurs. Since this step is skipped in production, we should just
+    // warn instead of throwing for this case.
+    spyOn(console, 'warn');
+    class Component {
+      render() {
+        return <span>{this.props.prop}</span>;
+      }
+    }
+    Component.propTypes = {
+      prop: null
+    };
+    ReactTestUtils.renderIntoDocument(<Component />);
+    expect(console.warn.calls.length).toBe(1);
+    expect(console.warn.calls[0].args[0]).toContain(
+      'Invariant Violation: Component: prop type `prop` is invalid; ' +
+      'it must be a function, usually from React.PropTypes.'
+    );
+  });
+
+  it('should warn on invalid context types', function() {
+    spyOn(console, 'warn');
+    class Component {
+      render() {
+        return <span>{this.props.prop}</span>;
+      }
+    }
+    Component.contextTypes = {
+      prop: null
+    };
+    ReactTestUtils.renderIntoDocument(<Component />);
+    expect(console.warn.calls.length).toBe(1);
+    expect(console.warn.calls[0].args[0]).toContain(
+      'Invariant Violation: Component: context type `prop` is invalid; ' +
+      'it must be a function, usually from React.PropTypes.'
+    );
+  });
+
+  it('should warn if getDefaultProps is specificed on the class', function() {
+    spyOn(console, 'warn');
+    class Component {
+      render() {
+        return <span>{this.props.prop}</span>;
+      }
+    }
+    Component.getDefaultProps = () => ({
+      prop: 'foo'
+    });
+    ReactTestUtils.renderIntoDocument(<Component />);
+    expect(console.warn.calls.length).toBe(1);
+    expect(console.warn.calls[0].args[0]).toContain(
+      'getDefaultProps is only used on classic React.createClass definitions.' +
+      ' Use a static property named `defaultProps` instead.'
+    );
+  });
+
 });