api-fetch: cleanup and improve unit tests #71439
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jsnajdr
added
[Type] Code Quality
jsnajdr
commented
Sep 1, 2025
| const body = 'FormData'; | ||
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| apiFetch( { | ||
| await apiFetch( { |
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Example of a synchronous test where the response promise was leaking out of the test. The promise resolves only after the test has already finished running.
| } ); | ||
| await expect( apiFetch( { path: '/random' } ) ).rejects.toEqual( { | ||
| code: 'bad_request', | ||
| message: 'Bad Request', |
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This removes the need to disable jest/no-conditional-expect. And also the test checks that the promise really rejects and fails otherwise. In the original code, the expect inside the catch callback would never run, and the test would finish without calling any expect.
| { once: true } | ||
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| } ) | ||
| ); |
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This is a realistic implementation of a fetch handler that:
- Returns a promise that never resolves.
- Aborts when someone calls
controller.abort().
The original version of the test just mocked fetch to reject with AbortError and then tested that this error was really thrown. The signal and the controller didn't play any role at all.
| status: 204, | ||
| } ); | ||
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| await expect( apiFetch( { path: '/random' } ) ).resolves.toBe( null ); |
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This test was wrong! It expected that apiFetch throws null, but in reality it returns null. The "204 No content" response doesn't have any body, so apiFetch returns null. And also avoids calling response.json() because that would throw.
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Size Change: 0 B Total Size: 1.92 MB ℹ️ View Unchanged
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Flaky tests detected in 8128f3d. 🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/17374318808
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While working on #67141 I noticed that unit tests for
apiFetchcan be greatly improved:jest/no-conditional-expectrule. It's possible when using theexpect().resolvesandexpect().rejectshelper. One test that was disabling this rule was wrong, namely the one that tests the 204 status with no body. It expectedapiFetchto throw, but that never happened, and the test succeeded anyway..mockResolvedValue,.mockRejectedValue. Together withasyncfunctions, this makes the code more concise.okfield. I plan to do another patch that starts using.okinstead of thecheckStatushelper, and that makes the tests fail.controllerandsignaldidn't play any role.awaitto all calls ofapiFetch, even for synchronous tests (typically checkingmock.toHaveBeenCalled). Otherwise, the async code execution leaks out of the test, continuing even after the test finished.globalThis.fetchinstead ofwindow.fetch: makes the library more compatible with Node and web workers. Admittedly a rather theoretical fix.