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docs: update jest README with testing examples and removed react setup instructions that are not currently available. #889

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docs: update jest README with testing examples and removed react setup instructions that are not currently available. #889

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docs: update jest README with testing examples and removed react set…
professorice Jun 18, 2025
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Merge branch 'main' into main
professorice Jul 1, 2025
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Merge branch 'main' into main
professorice Jul 24, 2025
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22 changes: 18 additions & 4 deletions packages/tooling/jest/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -28,17 +28,31 @@ Then in `jest.config.js` add `@launchdarkly/jest/{framework}` to setupFiles:
```js
// jest.config.js
module.exports = {
// for react
setupFiles: ['@launchdarkly/jest/react'],

// for react-native
setupFiles: ['@launchdarkly/jest/react-native'],
};
```

## Quickstart

TODO:
describe('Welcome component test', () => {
afterEach(() => {
resetLDMocks();
});

test('mock boolean flag correctly', () => {
mockFlags({ 'my-boolean-flag': true });
render(<Welcome />);
expect(screen.getByText('Flag value is true')).toBeTruthy();
});

test('mock ldClient correctly', () => {
const current = useLDClient();

current?.track('event');
expect(current.track).toHaveBeenCalledTimes(1);
});
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Bug: Hook Violation and Optional Chaining Inconsistency

The new test example violates React's rules of hooks by calling useLDClient() directly within a test function, which will cause a runtime error. Additionally, it has inconsistent optional chaining: current?.track('event') is used, but expect(current.track) accesses current.track directly, potentially leading to a TypeError if current is null/undefined.

Locations (1)

Fix in Cursor • Fix in Web

});

## Developing this package

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