Warn when second argument is passed to useCallback (#14729)

Author: gaearon

packages/react-dom/src/__tests__/ReactDOMServerIntegrationHooks-test.internal.js

@@ -613,8 +613,114 @@ describe('ReactDOMServerHooks', () => {
 });
 
 describe('useContext',()=>{
+itThrowsWhenRendering(
+'if used inside a class component',
+asyncrender=>{
+constContext=React.createContext({},()=>{});
+classCounterextendsReact.Component{
+render(){
+let[count]=useContext(Context);
+return<Texttext={count}/>;
+}
+}
+
+returnrender(<Counter/>);
+},
+'Hooks can only be called inside the body of a function component.',
+);
+});
+
+itRenders(
+'can use the same context multiple times in the same function',
+asyncrender=>{
+constContext=React.createContext({foo: 0,bar: 0,baz: 0});
+
+functionProvider(props){
+return(
+<Context.Provider
+value={{foo: props.foo,bar: props.bar,baz: props.baz}}>
+{props.children}
+</Context.Provider>
+);
+}
+
+functionFooAndBar(){
+const{foo}=useContext(Context);
+const{bar}=useContext(Context);
+return<Texttext={`Foo: ${foo}, Bar: ${bar}`}/>;
+}
+
+functionBaz(){
+const{baz}=useContext(Context);
+return<Texttext={'Baz: '+baz}/>;
+}
+
+classIndirectionextendsReact.Component{
+render(){
+returnthis.props.children;
+}
+}
+
+functionApp(props){
+return(
+<div>
+<Providerfoo={props.foo}bar={props.bar}baz={props.baz}>
+<Indirection>
+<Indirection>
+<FooAndBar/>
+</Indirection>
+<Indirection>
+<Baz/>
+</Indirection>
+</Indirection>
+</Provider>
+</div>
+);
+}
+
+constdomNode=awaitrender(<Appfoo={1}bar={3}baz={5}/>);
+expect(clearYields()).toEqual(['Foo: 1, Bar: 3','Baz: 5']);
+expect(domNode.childNodes.length).toBe(2);
+expect(domNode.firstChild.tagName).toEqual('SPAN');
+expect(domNode.firstChild.textContent).toEqual('Foo: 1, Bar: 3');
+expect(domNode.lastChild.tagName).toEqual('SPAN');
+expect(domNode.lastChild.textContent).toEqual('Baz: 5');
+},
+);
+
+itRenders('warns when bitmask is passed to useContext',asyncrender=>{
+letContext=React.createContext('Hi');
+
+functionFoo(){
+return<span>{useContext(Context,1)}</span>;
+}
+
+constdomNode=awaitrender(<Foo/>,1);
+expect(domNode.textContent).toBe('Hi');
+});
+
+describe('useDebugValue',()=>{
+itRenders('is a noop',asyncrender=>{
+functionCounter(props){
+constdebugValue=useDebugValue(123);
+return<Texttext={typeofdebugValue}/>;
+}
+
+constdomNode=awaitrender(<Counter/>);
+expect(domNode.textContent).toEqual('undefined');
+});
+});
+
+describe('readContext',()=>{
+functionreadContext(Context,observedBits){
+constdispatcher=
+React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED
+.ReactCurrentDispatcher.current;
+returndispatcher.readContext(Context,observedBits);
+}
+
 itRenders(
-'can use the same context multiple times in the same function',
+'can read the same context multiple times in the same function',
 asyncrender=>{
 constContext=React.createContext(
 {foo: 0,bar: 0,baz: 0},
@@ -643,13 +749,13 @@ describe('ReactDOMServerHooks', () => {
 }
 
 functionFooAndBar(){
-const{foo}=useContext(Context,0b001);
-const{bar}=useContext(Context,0b010);
+const{foo}=readContext(Context,0b001);
+const{bar}=readContext(Context,0b010);
 return<Texttext={`Foo: ${foo}, Bar: ${bar}`}/>;
 }
 
 functionBaz(){
-const{baz}=useContext(Context,0b100);
+const{baz}=readContext(Context,0b100);
 return<Texttext={'Baz: '+baz}/>;
 }
 
@@ -689,43 +795,6 @@ describe('ReactDOMServerHooks', () => {
 },
 );
 
-itThrowsWhenRendering(
-'if used inside a class component',
-asyncrender=>{
-constContext=React.createContext({},()=>{});
-classCounterextendsReact.Component{
-render(){
-let[count]=useContext(Context);
-return<Texttext={count}/>;
-}
-}
-
-returnrender(<Counter/>);
-},
-'Hooks can only be called inside the body of a function component.',
-);
-});
-
-describe('useDebugValue',()=>{
-itRenders('is a noop',asyncrender=>{
-functionCounter(props){
-constdebugValue=useDebugValue(123);
-return<Texttext={typeofdebugValue}/>;
-}
-
-constdomNode=awaitrender(<Counter/>);
-expect(domNode.textContent).toEqual('undefined');
-});
-});
-
-describe('readContext',()=>{
-functionreadContext(Context,observedBits){
-constdispatcher=
-React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED
-.ReactCurrentDispatcher.current;
-returndispatcher.readContext(Context,observedBits);
-}
-
 itRenders('with a warning inside useMemo and useReducer',asyncrender=>{
 constContext=React.createContext(42);