react-debug-tools accepts currentDispatcher ref as param (#14556)

* react-debug-tools accepts currentDispatcher ref as param

* ReactDebugHooks injected dispatcher ref is optional

Author: bvaughn

Diff for: packages/react-debug-tools/src/ReactDebugHooks.js

@@ -20,7 +20,7 @@ import {
   ForwardRef,
 } from 'shared/ReactWorkTags';
 
-const ReactCurrentDispatcher = ReactSharedInternals.ReactCurrentDispatcher;
+type CurrentDispatcherRef = typeof ReactSharedInternals.ReactCurrentDispatcher;
 
 // Used to track hooks called during a render
 
@@ -408,18 +408,25 @@ function buildTree(rootStack, readHookLog): HooksTree {
 export function inspectHooks<Props>(
   renderFunction: Props => React$Node,
   props: Props,
+  currentDispatcher: ?CurrentDispatcherRef,
 ): HooksTree {
-  let previousDispatcher = ReactCurrentDispatcher.current;
+  // DevTools will pass the current renderer's injected dispatcher.
+  // Other apps might compile debug hooks as part of their app though.
+  if (currentDispatcher == null) {
+    currentDispatcher = ReactSharedInternals.ReactCurrentDispatcher;
+  }
+
+  let previousDispatcher = currentDispatcher.current;
   let readHookLog;
-  ReactCurrentDispatcher.current = Dispatcher;
+  currentDispatcher.current = Dispatcher;
   let ancestorStackError;
   try {
     ancestorStackError = new Error();
     renderFunction(props);
   } finally {
     readHookLog = hookLog;
     hookLog = [];
-    ReactCurrentDispatcher.current = previousDispatcher;
+    currentDispatcher.current = previousDispatcher;
   }
   let rootStack = ErrorStackParser.parse(ancestorStackError);
   return buildTree(rootStack, readHookLog);
@@ -450,18 +457,19 @@ function inspectHooksOfForwardRef<Props, Ref>(
   renderFunction: (Props, Ref) => React$Node,
   props: Props,
   ref: Ref,
+  currentDispatcher: CurrentDispatcherRef,
 ): HooksTree {
-  let previousDispatcher = ReactCurrentDispatcher.current;
+  let previousDispatcher = currentDispatcher.current;
   let readHookLog;
-  ReactCurrentDispatcher.current = Dispatcher;
+  currentDispatcher.current = Dispatcher;
   let ancestorStackError;
   try {
     ancestorStackError = new Error();
     renderFunction(props, ref);
   } finally {
     readHookLog = hookLog;
     hookLog = [];
-    ReactCurrentDispatcher.current = previousDispatcher;
+    currentDispatcher.current = previousDispatcher;
   }
   let rootStack = ErrorStackParser.parse(ancestorStackError);
   return buildTree(rootStack, readHookLog);
@@ -482,7 +490,16 @@ function resolveDefaultProps(Component, baseProps) {
   return baseProps;
 }
 
-export function inspectHooksOfFiber(fiber: Fiber) {
+export function inspectHooksOfFiber(
+  fiber: Fiber,
+  currentDispatcher: ?CurrentDispatcherRef,
+) {
+  // DevTools will pass the current renderer's injected dispatcher.
+  // Other apps might compile debug hooks as part of their app though.
+  if (currentDispatcher == null) {
+    currentDispatcher = ReactSharedInternals.ReactCurrentDispatcher;
+  }
+
   if (
     fiber.tag !== FunctionComponent &&
     fiber.tag !== SimpleMemoComponent &&
@@ -506,9 +523,14 @@ export function inspectHooksOfFiber(fiber: Fiber) {
   try {
     setupContexts(contextMap, fiber);
     if (fiber.tag === ForwardRef) {
-      return inspectHooksOfForwardRef(type.render, props, fiber.ref);
+      return inspectHooksOfForwardRef(
+        type.render,
+        props,
+        fiber.ref,
+        currentDispatcher,
+      );
     }
-    return inspectHooks(type, props);
+    return inspectHooks(type, props, currentDispatcher);
   } finally {
     currentHook = null;
     restoreContexts(contextMap);

Diff for: packages/react-debug-tools/src/__tests__/ReactHooksInspection-test.internal.js

@@ -216,4 +216,37 @@ describe('ReactHooksInspection', () => {
       },
     ]);
   });
+
+  it('should support an injected dispatcher', () => {
+    function Foo(props) {
+      let [state] = React.useState('hello world');
+      return <div>{state}</div>;
+    }
+
+    let initial = {};
+    let current = initial;
+    let getterCalls = 0;
+    let setterCalls = [];
+    let FakeDispatcherRef = {
+      get current() {
+        getterCalls++;
+        return current;
+      },
+      set current(value) {
+        setterCalls.push(value);
+        current = value;
+      },
+    };
+
+    expect(() => {
+      ReactDebugTools.inspectHooks(Foo, {}, FakeDispatcherRef);
+    }).toThrow(
+      'Hooks can only be called inside the body of a function component.',
+    );
+
+    expect(getterCalls).toBe(1);
+    expect(setterCalls).toHaveLength(2);
+    expect(setterCalls[0]).not.toBe(initial);
+    expect(setterCalls[1]).toBe(initial);
+  });
 });

Diff for: packages/react-debug-tools/src/__tests__/ReactHooksInspectionIntegration-test.internal.js

@@ -241,4 +241,39 @@ describe('ReactHooksInspectionIntergration', () => {
     let tree = ReactDebugTools.inspectHooksOfFiber(childFiber);
     expect(tree).toEqual([{name: 'State', value: 'def', subHooks: []}]);
   });
+
+  it('should support an injected dispatcher', () => {
+    function Foo(props) {
+      let [state] = React.useState('hello world');
+      return <div>{state}</div>;
+    }
+
+    let initial = {};
+    let current = initial;
+    let getterCalls = 0;
+    let setterCalls = [];
+    let FakeDispatcherRef = {
+      get current() {
+        getterCalls++;
+        return current;
+      },
+      set current(value) {
+        setterCalls.push(value);
+        current = value;
+      },
+    };
+
+    let renderer = ReactTestRenderer.create(<Foo />);
+    let childFiber = renderer.root._currentFiber();
+    expect(() => {
+      ReactDebugTools.inspectHooksOfFiber(childFiber, FakeDispatcherRef);
+    }).toThrow(
+      'Hooks can only be called inside the body of a function component.',
+    );
+
+    expect(getterCalls).toBe(1);
+    expect(setterCalls).toHaveLength(2);
+    expect(setterCalls[0]).not.toBe(initial);
+    expect(setterCalls[1]).toBe(initial);
+  });
 });