ts-jest should be replaced by Babel

Currently ts-jest is used for tests, and it has a long-standing issue that it doesn’t support a sensible workflow for making changes: https://github.com/kulshekhar/ts-jest/issues/798

If I’m making breaking changes to the code and want to focus on a specific test suite or case, there’s no way to filter out the “diagnostics” from the other test cases, so the output can become flooded with messages.

The solution is to let Babel handle TS, since it doesn’t flood the Jest output with type errors.

[agilgur5]

Sorry, I’ll have to disagree that it “should” be replaced. That’s a very strong sentiment and Babel has a bunch of caveats, from not type-checking to being semantically different to not respecting tsconfig.json. TSDX supports lots of users and I don’t think those significant trade-offs make sense for a default setting. Strict defaults also mean solid best-practices out-of-the-box, which is the optimal experience.

You can customize your Jest config with a jest.config.js and change transform to use babel-jest or turn off ts-jest’s diagnostics if that’s what you’re looking for. That’s advanced usage and different from the defaults, so I think it makes sense that you’d have to configure that and that it’s not available out-of-the-box.

I’ll also disagree with your characterization of that issue as “long-standing” – it was responded to immediately and you were told that what you were seeking is impossible. You didn’t respond with further clarifications, didn’t provide a repro there or here, and there have been no up-votes in 1.5 years. I’m also fairly certain that tsc behaves the same exact way: any files that are imported will be type-checked. Maybe your problem is different from that, but without a repro or clarification, it’s difficult to understand what else might be the case.

In any case, sounds more like an upstream issue than here. You can customize Jest with a jest.config.js, so there’s already a way to work through your specific use case.

[slikts]

Issue about ts-jest vs Babel; quote from repo owner:

Even in its current state, I think using typescript via babel should be the way to go for testing. Type-checking should be separate from testing and tsc can be used for that directly. There’s no benefit in having the test runner also do the type-checking.

Another user about errors:

In local development we’re ok to ignore type errors in tests, cause either they can be caught at a later stage, or tests will fail anyway because something is undefined/missing.

Here’s a CRA feature request about type checking in tests where ts-jest’s possible legacy status is cited by a dev to rule it out:

We are eager to get some form of type checking in for test files, but we also don’t want to adopt a library that potentially won’t be maintained going forward. We are exploring other options to satisfy this that better fits in our current ecosystem of tools.

The issue I linked to initially was from before Babel support for TS, and it was just one that I was familiar with.