Part of #18610.
Our intent is to move `definePlugin`, `defineRule`, and `eslintCompatPlugin` to a separate package `@oxlint/plugins` (plural to avoid confusion with naming convention for plugins `oxlint-plugin-xxx`).
So rename the current entry point which exports these functions from `oxlint/plugin` to `oxlint/plugins` (plural).
This is technically breaking (only for types), but custom plugins are experimental.
The ruletester/defineRule/definePlugin are re-exported but with a `@deprecated` tag which I think is a good enough trade off
I want to avoid users bringing in a ton of custom plugin code when doing `import { defineConfig } from 'oxlint'`
Adapted from #15868. Enable `strictNullChecks` in TSConfig for `apps/oxlint`.
Rather than using `!` all over the place, I've added a function `assertIsNonNull`, which performs the same function. Idea is that we can later on produce a debug build where `assertIsNonNull` does an actual runtime assertion (rather than just a TS `asserts`) that the value is not `null` or `undefined`. We can use the debug build in tests, and catch any logic errors.
Unfortunately, TypeScript doesn't seem able to track side effects, so there seems to be no way to tell it "after calling `initAst()`, `ast` is always non-null". Don't want to switch to a having a `getAst` function which returns a non-null value, as that'd introduce unnecessary temp vars, and function calls, on hot paths. So this seems to be the best we can do without incurring runtime cost.
Implement the following deprecated `SourceCode` methods, related to tokens:
* `getTokenOrCommentBefore`
* `getTokenOrCommentAfter`
* `isSpaceBetweenTokens`
The 1st 2 are currently unimplemented, but can be implemented when we add tokens APIs.
`isSpaceBetweenTokens` implementation is flawed at present, in the same way as `isSpaceBetween` is, due to lack of tokens. But probably close enough to be useful in many cases. Added tests which demonstrate the flaw.
Format `oxlint` test fixtures. The directory `fixtures` contains not just the fixtures themselves, but also Oxlint plugins, which should be formatted.
Skip 2 specific test fixture files which must not be formatted to maintain correctness of the tests.
Implement `sourceCode.isSpaceBetween`. Implementation is not quite correct, because we don't have tokens yet. But it's better than no implementation at all. We can correct it once we have tokens.
The reason it's not correct is explained in comment on `isSpaceBetween` implementation, and the incorrect behavior is demonstrated in the test fixture.
Boshen