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Double-render function components with Hooks in DEV in StrictMode #14654

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merged 2 commits into from
Jan 23, 2019
Merged

Double-render function components with Hooks in DEV in StrictMode #14654

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f945a02
Revert "Revert "Double-render function components with Hooks in DEV i…
gaearon Jan 21, 2019
89f93c6
Merge branch 'master' into revert-14652-revert-14643-fun-sm-hooks
gaearon Jan 23, 2019
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53 changes: 53 additions & 0 deletions packages/react-reconciler/src/ReactFiberBeginWork.js
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -250,6 +250,23 @@ function updateForwardRef(
ref,
renderExpirationTime,
);
if (
debugRenderPhaseSideEffects ||
(debugRenderPhaseSideEffectsForStrictMode &&
workInProgress.mode & StrictMode)
) {
// Only double-render components with Hooks
if (workInProgress.memoizedState !== null) {
renderWithHooks(
current,
workInProgress,
render,
nextProps,
ref,
renderExpirationTime,
);
}
}
setCurrentPhase(null);
} else {
nextChildren = renderWithHooks(
Expand Down Expand Up @@ -543,6 +560,23 @@ function updateFunctionComponent(
context,
renderExpirationTime,
);
if (
debugRenderPhaseSideEffects ||
(debugRenderPhaseSideEffectsForStrictMode &&
workInProgress.mode & StrictMode)
) {
// Only double-render components with Hooks
if (workInProgress.memoizedState !== null) {
renderWithHooks(
current,
workInProgress,
Component,
nextProps,
context,
renderExpirationTime,
);
}
}
setCurrentPhase(null);
} else {
nextChildren = renderWithHooks(
Expand Down Expand Up @@ -1210,6 +1244,25 @@ function mountIndeterminateComponent(
} else {
// Proceed under the assumption that this is a function component
workInProgress.tag = FunctionComponent;
if (__DEV__) {
if (
debugRenderPhaseSideEffects ||
(debugRenderPhaseSideEffectsForStrictMode &&
workInProgress.mode & StrictMode)
) {
// Only double-render components with Hooks
if (workInProgress.memoizedState !== null) {
renderWithHooks(
null,
workInProgress,
Component,
props,
context,
renderExpirationTime,
);
}
}
}
reconcileChildren(null, workInProgress, value, renderExpirationTime);
if (__DEV__) {
validateFunctionComponentInDev(workInProgress, Component);
Expand Down
220 changes: 220 additions & 0 deletions packages/react-reconciler/src/__tests__/ReactHooks-test.internal.js
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Original file line number Diff line number Diff line change
Expand Up @@ -841,6 +841,226 @@ describe('ReactHooks', () => {
);
});

it('double-invokes components with Hooks in Strict Mode', () => {
ReactFeatureFlags.debugRenderPhaseSideEffectsForStrictMode = true;

const {useState, StrictMode} = React;
let renderCount = 0;

function NoHooks() {
renderCount++;
return <div />;
}

function HasHooks() {
useState(0);
renderCount++;
return <div />;
}

const FwdRef = React.forwardRef((props, ref) => {
renderCount++;
return <div />;
});

const FwdRefHasHooks = React.forwardRef((props, ref) => {
useState(0);
renderCount++;
return <div />;
});

const Memo = React.memo(props => {
renderCount++;
return <div />;
});

const MemoHasHooks = React.memo(props => {
useState(0);
renderCount++;
return <div />;
});

function Factory() {
return {
state: {},
render() {
renderCount++;
return <div />;
},
};
}

let renderer = ReactTestRenderer.create(null);

renderCount = 0;
renderer.update(<NoHooks />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(<NoHooks />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(
<StrictMode>
<NoHooks />
</StrictMode>,
);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(
<StrictMode>
<NoHooks />
</StrictMode>,
);
expect(renderCount).toBe(1);

renderCount = 0;
renderer.update(<FwdRef />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(<FwdRef />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(
<StrictMode>
<FwdRef />
</StrictMode>,
);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(
<StrictMode>
<FwdRef />
</StrictMode>,
);
expect(renderCount).toBe(1);

renderCount = 0;
renderer.update(<Memo arg={1} />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(<Memo arg={2} />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(
<StrictMode>
<Memo arg={1} />
</StrictMode>,
);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(
<StrictMode>
<Memo arg={2} />
</StrictMode>,
);
expect(renderCount).toBe(1);

renderCount = 0;
renderer.update(<Factory />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(<Factory />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(
<StrictMode>
<Factory />
</StrictMode>,
);
expect(renderCount).toBe(__DEV__ ? 2 : 1); // Treated like a class
renderCount = 0;
renderer.update(
<StrictMode>
<Factory />
</StrictMode>,
);
expect(renderCount).toBe(__DEV__ ? 2 : 1); // Treated like a class

renderCount = 0;
renderer.update(<HasHooks />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(<HasHooks />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(
<StrictMode>
<HasHooks />
</StrictMode>,
);
expect(renderCount).toBe(__DEV__ ? 2 : 1); // Has Hooks
renderCount = 0;
renderer.update(
<StrictMode>
<HasHooks />
</StrictMode>,
);
expect(renderCount).toBe(__DEV__ ? 2 : 1); // Has Hooks

renderCount = 0;
renderer.update(<FwdRefHasHooks />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(<FwdRefHasHooks />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(
<StrictMode>
<FwdRefHasHooks />
</StrictMode>,
);
expect(renderCount).toBe(__DEV__ ? 2 : 1); // Has Hooks
renderCount = 0;
renderer.update(
<StrictMode>
<FwdRefHasHooks />
</StrictMode>,
);
expect(renderCount).toBe(__DEV__ ? 2 : 1); // Has Hooks

renderCount = 0;
renderer.update(<MemoHasHooks arg={1} />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(<MemoHasHooks arg={2} />);
expect(renderCount).toBe(1);
renderCount = 0;
renderer.update(
<StrictMode>
<MemoHasHooks arg={1} />
</StrictMode>,
);
expect(renderCount).toBe(__DEV__ ? 2 : 1); // Has Hooks
renderCount = 0;
renderer.update(
<StrictMode>
<MemoHasHooks arg={2} />
</StrictMode>,
);
expect(renderCount).toBe(__DEV__ ? 2 : 1); // Has Hooks
});

it('double-invokes useMemo in DEV StrictMode despite []', () => {
ReactFeatureFlags.debugRenderPhaseSideEffectsForStrictMode = true;
const {useMemo, StrictMode} = React;

let useMemoCount = 0;
function BadUseMemo() {
useMemo(() => {
useMemoCount++;
}, []);
return <div />;
}

useMemoCount = 0;
ReactTestRenderer.create(
<StrictMode>
<BadUseMemo />
</StrictMode>,
);
expect(useMemoCount).toBe(__DEV__ ? 2 : 1); // Has Hooks
});

it('warns on using differently ordered hooks on subsequent renders', () => {
const {useState, useReducer} = React;
function useCustomHook() {
Expand Down