Upgrade Jest and use TS for Jest config #97
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v27 is the latest version of Jest and introduces these major changes:
* `node` is now the default environment instead of `jsdom`. This
results in faster runtimes.
* The runner has been completely rewritten as `jest-circus` which is
also the default, replacing `jest-jasmine2`.
* This should have no impact on us as we don't rely on any
Jasmine-specific APIs, but is nice to know.
* The "modern" version of Fake Timers (enabled via
`jest.useFakeTimers("modern")`) is now the default.
More info here: <https://jestjs.io/blog/2021/05/25/jest-27>
Additionally, to ensure that we make use of all of the latest and
greatest, this PR regenerates the Jest config file (as
`jest.config.ts`). This has the added improvement that each option is
now commented so we know exactly what each one does.
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I started going through the new config, but it looks like most of our old config was discarded. Perhaps by mistake? Also lots of lint errors. |
| // ], | ||
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| // An array of file extensions your modules use | ||
| // moduleFileExtensions: [ |
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The default value matches our previously provided value, so I opted to leave the default.
| // testLocationInResults: false, | ||
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| // The glob patterns Jest uses to detect test files | ||
| // testMatch: [ |
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The default value covers more than the pattern we provided, but it also includes that pattern. Is there a reason why we want to override this? Was it just to communicate that test files ought to 1) be named *.test.ts and 2) be colocated with implementation files?
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I'm guessing that it's because it used to diverge from the standard. The default seems fine to me.
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@Gudahtt Apologies for the rush job on this, just wanted to make a PR based on the changes I'd made to |
| files: ['jest.config.ts'], | ||
| rules: { | ||
| // TODO: Migrate to our shared config | ||
| 'import/no-anonymous-default-export': 'off', |
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👀
I was curious what this rule was for so I just looked up the original PR where it was added. Apparently the advantage is that it "improves the greppability of the codebase". That is, when searching for an identifier, sometimes it can be hard to find what you're looking for if that identifier is only in the filename and not represented in the file itself.
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I have definitely had that problem myself, so in general this rule seems beneficial to me. But it does seem out-of-place when applied to a top-level config file.
v27 is the latest version of Jest and introduces these major changes:
nodeis now the default environment instead ofjsdom. Thisresults in faster runtimes.
jest-circuswhich isalso the default, replacing
jest-jasmine2.Jasmine-specific APIs, but is nice to know.
jest.useFakeTimers("modern")) is now the default.More info here: https://jestjs.io/blog/2021/05/25/jest-27
Additionally, to ensure that we make use of all of the latest and
greatest, this PR regenerates the Jest config file (as
jest.config.ts). This has the added improvement that each option isnow commented so we know exactly what each one does.