Fixes umount setState error. closes #4

Author: ctrlplusb

src/__tests__/createAsyncComponent.test.js

@@ -0,0 +1,25 @@
+import React from 'react';
+import sinon from 'sinon';
+import { mount } from 'enzyme';
+
+import createAsyncComponent from '../createAsyncComponent';
+
+describe('createAsyncComponent', () => {
+  it('should handle unmounting ensuring that resolved promises do not call setState', () => {
+    const resolveDelay = 10;
+    const Bob = createAsyncComponent({
+      resolve: () => new Promise(resolve =>
+        setTimeout(
+          () => resolve(() => <div>bob</div>),
+          resolveDelay,
+        ),
+      ),
+    });
+    const setStateSpy = sinon.spy(Bob.prototype, 'setState');
+    const renderWrapper = mount(<Bob />);
+    expect(setStateSpy.callCount).toEqual(0);
+    renderWrapper.unmount();
+    return new Promise(resolve => setTimeout(resolve, resolveDelay + 2))
+      .then(() => expect(setStateSpy.callCount).toEqual(0));
+  });
+});

src/createAsyncComponent.js

@@ -63,11 +63,19 @@ function createAsyncComponent(args) {
     }
 
     resolveComponent() {
-      return getResolver().then(Component =>
+      return getResolver().then((Component) => {
+        if (this.unmounted) {
+          // The component is unmounted, so no need to set the state.
+          return;
+        }
         this.setState({
           Component: es6Resolve(Component),
-        }),
-      );
+        });
+      });
+    }
+
+    componentWillUnmount() {
+      this.unmounted = true;
     }
 
     render() {