Unit tests for unmounted setState and isMounted

src/renderers/shared/reconciler/__tests__/ReactComponentLifeCycle-test.js

@@ -257,6 +257,32 @@ describe('ReactComponentLifeCycle', function() {
     );
   });
 
+  it('should correctly determine if a null component is mounted', function() {
+    spyOn(console, 'error');
+    var Component = React.createClass({
+      componentWillMount: function() {
+        expect(this.isMounted()).toBeFalsy();
+      },
+      componentDidMount: function() {
+        expect(this.isMounted()).toBeTruthy();
+      },
+      render: function() {
+        expect(this.isMounted()).toBeFalsy();
+        return null;
+      },
+    });
+
+    var element = <Component />;
+
+    var instance = ReactTestUtils.renderIntoDocument(element);
+    expect(instance.isMounted()).toBeTruthy();
+
+    expect(console.error.argsForCall.length).toBe(1);
+    expect(console.error.argsForCall[0][0]).toContain(
+      'Component is accessing isMounted inside its render()'
+    );
+  });
+
   it('isMounted should return false when unmounted', function () {
     var Component = React.createClass({
       render: function() {

src/renderers/shared/reconciler/__tests__/ReactCompositeComponent-test.js

@@ -286,11 +286,14 @@ describe('ReactCompositeComponent', function() {
     var container = document.createElement('div');
     document.body.appendChild(container);
 
+    var renders = 0;
+
     var Component = React.createClass({
       getInitialState: function() {
         return {value: 0};
       },
       render: function() {
+        renders++;
         return <div />;
       },
     });
@@ -299,12 +302,20 @@ describe('ReactCompositeComponent', function() {
     expect(instance.setState).not.toBeDefined();
 
     instance = React.render(instance, container);
+
+    expect(renders).toBe(1);
+
     instance.setState({value: 1});
 
     expect(console.error.calls.length).toBe(0);
 
+    expect(renders).toBe(2);
+
     React.unmountComponentAtNode(container);
     instance.setState({value: 2});
+
+    expect(renders).toBe(2);
+
     expect(console.error.calls.length).toBe(1);
     expect(console.error.argsForCall[0][0]).toBe(
       'Warning: setState(...): Can only update a mounted or ' +