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index.js
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index.js
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import FixtureSet from '../../FixtureSet';
import TestCase from '../../TestCase';
const React = window.React;
const ReactDOM = window.ReactDOM;
function BadRender(props) {
props.doThrow();
}
class BadDidMount extends React.Component {
componentDidMount() {
this.props.doThrow();
}
render() {
return null;
}
}
class ErrorBoundary extends React.Component {
static defaultProps = {
buttonText: 'Trigger error',
badChildType: BadRender,
};
state = {
shouldThrow: false,
didThrow: false,
error: null,
};
componentDidCatch(error) {
this.setState({error, didThrow: true});
}
triggerError = () => {
this.setState({
shouldThrow: true,
});
};
render() {
if (this.state.didThrow) {
if (this.state.error) {
return <p>Captured an error: {this.state.error.message}</p>;
} else {
return <p>Captured an error: {String(this.state.error)}</p>;
}
}
if (this.state.shouldThrow) {
const BadChild = this.props.badChildType;
return <BadChild doThrow={this.props.doThrow} />;
}
return <button onClick={this.triggerError}>{this.props.buttonText}</button>;
}
}
class Example extends React.Component {
state = {key: 0};
restart = () => {
this.setState(state => ({key: state.key + 1}));
};
render() {
return (
<div>
<button onClick={this.restart}>Reset</button>
<ErrorBoundary
buttonText={this.props.buttonText}
doThrow={this.props.doThrow}
key={this.state.key}
/>
</div>
);
}
}
class TriggerErrorAndCatch extends React.Component {
container = document.createElement('div');
triggerErrorAndCatch = () => {
try {
ReactDOM.flushSync(() => {
ReactDOM.render(
<BadRender
doThrow={() => {
throw new Error('Caught error');
}}
/>,
this.container
);
});
} catch (e) {}
};
render() {
return (
<button onClick={this.triggerErrorAndCatch}>
Trigger error and catch
</button>
);
}
}
function silenceWindowError(event) {
event.preventDefault();
}
class SilenceErrors extends React.Component {
state = {
silenceErrors: false,
};
componentDidMount() {
if (this.state.silenceErrors) {
window.addEventListener('error', silenceWindowError);
}
}
componentDidUpdate(prevProps, prevState) {
if (!prevState.silenceErrors && this.state.silenceErrors) {
window.addEventListener('error', silenceWindowError);
} else if (prevState.silenceErrors && !this.state.silenceErrors) {
window.removeEventListener('error', silenceWindowError);
}
}
componentWillUnmount() {
if (this.state.silenceErrors) {
window.removeEventListener('error', silenceWindowError);
}
}
render() {
return (
<div>
<label>
<input
type="checkbox"
value={this.state.silenceErrors}
onChange={() =>
this.setState(state => ({
silenceErrors: !state.silenceErrors,
}))
}
/>
Silence errors
</label>
{this.state.silenceErrors && (
<div>
{this.props.children}
<br />
<hr />
<b style={{color: 'red'}}>
Don't forget to uncheck "Silence errors" when you're done with
this test!
</b>
</div>
)}
</div>
);
}
}
class GetEventTypeDuringUpdate extends React.Component {
state = {};
onClick = () => {
this.expectUpdate = true;
this.forceUpdate();
};
componentDidUpdate() {
if (this.expectUpdate) {
this.expectUpdate = false;
this.setState({eventType: window.event.type});
setTimeout(() => {
this.setState({cleared: !window.event});
});
}
}
render() {
return (
<div className="test-fixture">
<button onClick={this.onClick}>Trigger callback in event.</button>
{this.state.eventType ? (
<p>
Got <b>{this.state.eventType}</b> event.
</p>
) : (
<p>Got no event</p>
)}
{this.state.cleared ? (
<p>Event cleared correctly.</p>
) : (
<p>Event failed to clear.</p>
)}
</div>
);
}
}
class SilenceRecoverableError extends React.Component {
render() {
return (
<SilenceErrors>
<ErrorBoundary
badChildType={BadRender}
buttonText={'Throw (render phase)'}
doThrow={() => {
throw new Error('Silenced error (render phase)');
}}
/>
<ErrorBoundary
badChildType={BadDidMount}
buttonText={'Throw (commit phase)'}
doThrow={() => {
throw new Error('Silenced error (commit phase)');
}}
/>
</SilenceErrors>
);
}
}
class TrySilenceFatalError extends React.Component {
container = document.createElement('div');
triggerErrorAndCatch = () => {
try {
ReactDOM.flushSync(() => {
ReactDOM.render(
<BadRender
doThrow={() => {
throw new Error('Caught error');
}}
/>,
this.container
);
});
} catch (e) {}
};
render() {
return (
<SilenceErrors>
<button onClick={this.triggerErrorAndCatch}>Throw fatal error</button>
</SilenceErrors>
);
}
}
function naiveMemoize(fn) {
let memoizedEntry;
return function () {
if (!memoizedEntry) {
memoizedEntry = {result: null};
memoizedEntry.result = fn();
}
return memoizedEntry.result;
};
}
let memoizedFunction = naiveMemoize(function () {
throw new Error('Passed');
});
export default class ErrorHandlingTestCases extends React.Component {
render() {
return (
<FixtureSet title="Error handling">
<TestCase
title="Break on uncaught exceptions"
description="In DEV, errors should be treated as uncaught, even though React catches them internally">
<TestCase.Steps>
<li>Open the browser DevTools</li>
<li>Make sure "Pause on exceptions" is enabled</li>
<li>Make sure "Pause on caught exceptions" is disabled</li>
<li>Click the "Trigger error" button</li>
<li>Click the reset button</li>
</TestCase.Steps>
<TestCase.ExpectedResult>
The DevTools should pause at the line where the error was thrown, in
the BadRender component. After resuming, the "Trigger error" button
should be replaced with "Captured an error: Oops!" Clicking reset
should reset the test case.
<br />
<br />
In the console, you should see <b>two</b> messages: the actual error
("Oops") printed natively by the browser with its JavaScript stack,
and our addendum ("The above error occurred in BadRender component")
with a React component stack.
</TestCase.ExpectedResult>
<Example
doThrow={() => {
throw new Error('Oops!');
}}
/>
</TestCase>
<TestCase title="Throwing null" description="">
<TestCase.Steps>
<li>Click the "Trigger error" button</li>
<li>Click the reset button</li>
</TestCase.Steps>
<TestCase.ExpectedResult>
The "Trigger error" button should be replaced with "Captured an
error: null". Clicking reset should reset the test case.
</TestCase.ExpectedResult>
<Example
doThrow={() => {
throw null; // eslint-disable-line no-throw-literal
}}
/>
</TestCase>
<TestCase title="Throwing memoized result" description="">
<TestCase.Steps>
<li>Click the "Trigger error" button</li>
<li>Click the reset button</li>
</TestCase.Steps>
<TestCase.ExpectedResult>
The "Trigger error" button should be replaced with "Captured an
error: Passed". Clicking reset should reset the test case.
</TestCase.ExpectedResult>
<Example
doThrow={() => {
memoizedFunction().value;
}}
/>
</TestCase>
<TestCase
title="Cross-origin errors (development mode only)"
description="">
<TestCase.Steps>
<li>Click the "Trigger cross-origin error" button</li>
<li>Click the reset button</li>
</TestCase.Steps>
<TestCase.ExpectedResult>
The "Trigger error" button should be replaced with "Captured an
error: A cross-origin error was thrown [...]". The actual error
message should be logged to the console: "Uncaught Error: Expected
true to be false".
</TestCase.ExpectedResult>
<Example
buttonText="Trigger cross-origin error"
doThrow={() => {
// The `expect` module is loaded via unpkg, so that this assertion
// triggers a cross-origin error
window.expect(true).toBe(false);
}}
/>
</TestCase>
<TestCase
title="Errors are logged even if they're caught (development mode only)"
description="">
<TestCase.Steps>
<li>Click the "Trigger render error and catch" button</li>
</TestCase.Steps>
<TestCase.ExpectedResult>
Open the console. "Uncaught Error: Caught error" should have been
logged by the browser. You should also see our addendum ("The above
error...").
</TestCase.ExpectedResult>
<TriggerErrorAndCatch />
</TestCase>
<TestCase
title="Recoverable errors can be silenced with preventDefault (development mode only)"
description="">
<TestCase.Steps>
<li>Check the "Silence errors" checkbox below</li>
<li>Click the "Throw (render phase)" button</li>
<li>Click the "Throw (commit phase)" button</li>
<li>Uncheck the "Silence errors" checkbox</li>
</TestCase.Steps>
<TestCase.ExpectedResult>
Open the console. You shouldn't see <b>any</b> messages in the
console: neither the browser error, nor our "The above error"
addendum, from either of the buttons. The buttons themselves should
get replaced by two labels: "Captured an error: Silenced error
(render phase)" and "Captured an error: Silenced error (commit
phase)".
</TestCase.ExpectedResult>
<SilenceRecoverableError />
</TestCase>
<TestCase
title="Fatal errors cannot be silenced with preventDefault (development mode only)"
description="">
<TestCase.Steps>
<li>Check the "Silence errors" checkbox below</li>
<li>Click the "Throw fatal error" button</li>
<li>Uncheck the "Silence errors" checkbox</li>
</TestCase.Steps>
<TestCase.ExpectedResult>
Open the console. "Error: Caught error" should have been logged by
React. You should also see our addendum ("The above error...").
</TestCase.ExpectedResult>
<TrySilenceFatalError />
</TestCase>
{window.hasOwnProperty('event') ? (
<TestCase
title="Error handling does not interfere with window.event"
description="">
<TestCase.Steps>
<li>Click the "Trigger callback in event" button</li>
</TestCase.Steps>
<TestCase.ExpectedResult>
You should see "Got <b>click</b> event" and "Event cleared
successfully" below.
</TestCase.ExpectedResult>
<GetEventTypeDuringUpdate />
</TestCase>
) : null}
</FixtureSet>
);
}
}