Jest testing framework #997

[andretchen0]

This adds the Jest testing framework to the project.

Adding tests

Copying the style of the React repository, tests can be added into /src/__tests__/*.js.

Note

There was discussion of putting Jest tests into a folder named __jest__ as a precaution against conflicts with a future testing framework. This PR does not do that. It follows Jest's defaults.

Reasoning: If an additional, testing framework is added in the future and there is a naming conflict, __tests__ can be renamed and the jest.config.js testMatch field can be updated to match. In the meantime, there's no reason to change the defaults.

Writing tests

Tests can be written following the examples from the Jest documentation.

However, Ancient Beast's already-installed linter as well as the checks run on Github require that the Jest module values be imported explicitly, e.g.,

import { expect, describe, test } from '@jest/globals';

See /src/__tests__/utility/string.js for an example.

Running tests

The test runner was added to the existing npm run test.

In addition, the following commands were added to package.json:

• npm run jest – Run tests
• npm run start:jest – Watch test files and rerun when modified

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Name	Status	Preview	Updated (UTC)
ancientbeast	✅ Ready (Inspect)	Visit Preview	Apr 8, 2023 1:22pm

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[DreadKnight]

@andretchen0 Well done! Merged this in. Some of that info from original post should be included either in our Contribution guide or in a wiki page (linked in from the guide as well perhaps).

[DreadKnight]

Added section in the Contribution guide about it bec7e55