data-snapshot
v1.0.1
Published
Generic mock data manager for real endpoints.
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data-snapshot 📸
data-snapshot
is a generic mock data manager for JavaScript tests, that helps you use data from real endpoints in tests.
On first run / update, data-snapshot
executes the thunk (which returns a promise), and then writes the result of the promise to disk to avoid network calls on subsequent test runs.
A __data_snapshots__
is created adjacent to your test file (similar to Jest's __snapshots__
), with the same name as your test file. Mock data is stored within that file.
You can then update your data by rerunning your specs with a --updateSnapshot
/-u
flag, or by deleting the snapshot file.
Data snapshots should be committed to version control, as regular snapshot files are. The snapshot file is then used in CI.
Installing
npm i --save-dev data-snapshot
Usage
import dataSnapshot from 'data-snapshot';
// hits endpoint on first run; resolves from disk on 2nd
const fetchData = id => fetch(`/api/${id}`).then(r => r.json());
test('some-spec', async () => {
const data = await dataSnapshot('key', () => fetchData(1));
expect(data.a).toBe(true);
});
Expires
The data is never actually expired (to avoid CI unintentionally triggering an Ajax call, etc). However, if you would like to be reminded with a console warning to update your data periodically, set an expires flag.
const ONE_MONTHISH = 1000 * 60 * 60 * 24 * 30;
dataSnapshot('key', thunkPromise, {expires: Date.now() + ONE_MONTHISH});
API
dataSnapshot<D>(
name: string,
thunkPromise: () => Promise<D>,
opts: {expires?: number} = {}
): Promise<D>
--updateSnapshot
/-u
will re execute your data fetcher (jest --updateSnapshot
).
Running the tests
npm test
Built With
Contributing
Please read CODE_OF_CONDUCT.md for details on our Code of Conduct.
To contribute, please open an issue, or submit a pull request with appropriate test coverage.
License
This project is licensed under the BSD-2-Clause license - see the LICENSE.md file for details