Fix react-is memo and lazy type checks

Author: Brian Vaughn

packages/react-is/src/ReactIs.js

@@ -48,14 +48,14 @@ export function typeOf(object: any) {
             switch ($$typeofType) {
               case REACT_CONTEXT_TYPE:
               case REACT_FORWARD_REF_TYPE:
+              case REACT_LAZY_TYPE:
+              case REACT_MEMO_TYPE:
               case REACT_PROVIDER_TYPE:
                 return $$typeofType;
               default:
                 return $$typeof;
             }
         }
-      case REACT_LAZY_TYPE:
-      case REACT_MEMO_TYPE:
       case REACT_PORTAL_TYPE:
         return $$typeof;
     }

packages/react-is/src/__tests__/ReactIs-test.js

@@ -71,6 +71,7 @@ describe('ReactIs', () => {
 
   it('should identify context consumers', () => {
     const Context = React.createContext(false);
+    expect(ReactIs.isValidElementType(Context.Consumer)).toBe(true);
     expect(ReactIs.typeOf(<Context.Consumer />)).toBe(ReactIs.ContextConsumer);
     expect(ReactIs.isContextConsumer(<Context.Consumer />)).toBe(true);
     expect(ReactIs.isContextConsumer(<Context.Provider />)).toBe(false);
@@ -79,6 +80,7 @@ describe('ReactIs', () => {
 
   it('should identify context providers', () => {
     const Context = React.createContext(false);
+    expect(ReactIs.isValidElementType(Context.Provider)).toBe(true);
     expect(ReactIs.typeOf(<Context.Provider />)).toBe(ReactIs.ContextProvider);
     expect(ReactIs.isContextProvider(<Context.Provider />)).toBe(true);
     expect(ReactIs.isContextProvider(<Context.Consumer />)).toBe(false);
@@ -106,13 +108,15 @@ describe('ReactIs', () => {
 
   it('should identify ref forwarding component', () => {
     const RefForwardingComponent = React.forwardRef((props, ref) => null);
+    expect(ReactIs.isValidElementType(RefForwardingComponent)).toBe(true);
     expect(ReactIs.typeOf(<RefForwardingComponent />)).toBe(ReactIs.ForwardRef);
     expect(ReactIs.isForwardRef(<RefForwardingComponent />)).toBe(true);
     expect(ReactIs.isForwardRef({type: ReactIs.StrictMode})).toBe(false);
     expect(ReactIs.isForwardRef(<div />)).toBe(false);
   });
 
   it('should identify fragments', () => {
+    expect(ReactIs.isValidElementType(React.Fragment)).toBe(true);
     expect(ReactIs.typeOf(<React.Fragment />)).toBe(ReactIs.Fragment);
     expect(ReactIs.isFragment(<React.Fragment />)).toBe(true);
     expect(ReactIs.isFragment({type: ReactIs.Fragment})).toBe(false);
@@ -124,35 +128,40 @@ describe('ReactIs', () => {
   it('should identify portals', () => {
     const div = document.createElement('div');
     const portal = ReactDOM.createPortal(<div />, div);
+    expect(ReactIs.isValidElementType(portal)).toBe(false);
     expect(ReactIs.typeOf(portal)).toBe(ReactIs.Portal);
     expect(ReactIs.isPortal(portal)).toBe(true);
     expect(ReactIs.isPortal(div)).toBe(false);
   });
 
   it('should identify memo', () => {
     const Component = () => React.createElement('div');
-    const memoized = React.memo(Component);
-    expect(ReactIs.typeOf(memoized)).toBe(ReactIs.Memo);
-    expect(ReactIs.isMemo(memoized)).toBe(true);
-    expect(ReactIs.isMemo(Component)).toBe(false);
+    const Memoized = React.memo(Component);
+    expect(ReactIs.isValidElementType(Memoized)).toBe(true);
+    expect(ReactIs.typeOf(<Memoized />)).toBe(ReactIs.Memo);
+    expect(ReactIs.isMemo(<Memoized />)).toBe(true);
+    expect(ReactIs.isMemo(<Component />)).toBe(false);
   });
 
   it('should identify lazy', () => {
     const Component = () => React.createElement('div');
-    const lazyComponent = React.lazy(() => Component);
-    expect(ReactIs.typeOf(lazyComponent)).toBe(ReactIs.Lazy);
-    expect(ReactIs.isLazy(lazyComponent)).toBe(true);
-    expect(ReactIs.isLazy(Component)).toBe(false);
+    const LazyComponent = React.lazy(() => Component);
+    expect(ReactIs.isValidElementType(LazyComponent)).toBe(true);
+    expect(ReactIs.typeOf(<LazyComponent />)).toBe(ReactIs.Lazy);
+    expect(ReactIs.isLazy(<LazyComponent />)).toBe(true);
+    expect(ReactIs.isLazy(<Component />)).toBe(false);
   });
 
   it('should identify strict mode', () => {
+    expect(ReactIs.isValidElementType(React.StrictMode)).toBe(true);
     expect(ReactIs.typeOf(<React.StrictMode />)).toBe(ReactIs.StrictMode);
     expect(ReactIs.isStrictMode(<React.StrictMode />)).toBe(true);
     expect(ReactIs.isStrictMode({type: ReactIs.StrictMode})).toBe(false);
     expect(ReactIs.isStrictMode(<div />)).toBe(false);
   });
 
   it('should identify suspense', () => {
+    expect(ReactIs.isValidElementType(React.Suspense)).toBe(true);
     expect(ReactIs.typeOf(<React.Suspense />)).toBe(ReactIs.Suspense);
     expect(ReactIs.isSuspense(<React.Suspense />)).toBe(true);
     expect(ReactIs.isSuspense({type: ReactIs.Suspense})).toBe(false);
@@ -161,6 +170,7 @@ describe('ReactIs', () => {
   });
 
   it('should identify profile root', () => {
+    expect(ReactIs.isValidElementType(React.Profiler)).toBe(true);
     expect(
       ReactIs.typeOf(<React.Profiler id="foo" onRender={jest.fn()} />),
     ).toBe(ReactIs.Profiler);

packages/react-test-renderer/src/ReactShallowRenderer.js

@@ -542,7 +542,7 @@ class ReactShallowRenderer {
     );
     invariant(
       isForwardRef(element) ||
-        (typeof element.type === 'function' || isMemo(element.type)),
+        (typeof element.type === 'function' || isMemo(element)),
       'ReactShallowRenderer render(): Shallow rendering works only with custom ' +
         'components, but the provided element type was `%s`.',
       Array.isArray(element.type)
@@ -559,15 +559,15 @@ class ReactShallowRenderer {
       this._reset();
     }
 
-    const elementType = isMemo(element.type) ? element.type.type : element.type;
+    const elementType = isMemo(element) ? element.type.type : element.type;
     const previousElement = this._element;
 
     this._rendering = true;
     this._element = element;
     this._context = getMaskedContext(elementType.contextTypes, context);
 
     // Inner memo component props aren't currently validated in createElement.
-    if (isMemo(element.type) && elementType.propTypes) {
+    if (isMemo(element) && elementType.propTypes) {
       currentlyValidatingElement = element;
       checkPropTypes(
         elementType.propTypes,
@@ -618,7 +618,7 @@ class ReactShallowRenderer {
         this._mountClassComponent(elementType, element, this._context);
       } else {
         let shouldRender = true;
-        if (isMemo(element.type) && previousElement !== null) {
+        if (isMemo(element) && previousElement !== null) {
           // This is a Memo component that is being re-rendered.
           const compare = element.type.compare || shallowEqual;
           if (compare(previousElement.props, element.props)) {
@@ -807,7 +807,7 @@ function getDisplayName(element) {
   } else if (typeof element.type === 'string') {
     return element.type;
   } else {
-    const elementType = isMemo(element.type) ? element.type.type : element.type;
+    const elementType = isMemo(element) ? element.type.type : element.type;
     return elementType.displayName || elementType.name || 'Unknown';
   }
 }