- some additional ts-jest config is needed to parse `index.ts`
  - since Rollup isn't used when importing files during testing, we need to enable `esModuleInterop`
    - the import of `findCacheDir` was immediately erroring without this (and maybe more, but `esModuleInterop` made the import work)
  - add `tsconfig.test.json` for this purpose
  - use `ts-jest` JSDoc types to get types for the ts-jest config as well

- add an integration/ dir in the __tests__/ dir for all integration tests
  - add a fixtures/ dir in there as well for integration test fixtures
    - add a `tsconfig.json` for all fixtures to use
      - basically so that rpt2 source code is not `include`d, though also bc this may be good to customize for fixtures
    - add a simple fixture with "no-errors" that does an import and a type-only import

- add a simple integration test that just ensures that all files are part of the bundle
  - the bundled `index` file and each file's declaration and declaration map
  - and no _other_ files!
  - for Rollup, need to use paths relative to the root of the whole project
    - probably because that is `cwd` when running `jest` from root
    - will probably abstract out helpers here in the future as the test suite grows
  - 70% coverage of `index.ts` with just this one test!

- update CONTRIBUTING.md now that an integration test exists

- similar to the unit test suite

- also remove the `.only` that I was using during development

- should probably do this for each integration test suite

- refactor: split out a `genBundle` func to DRY things up
  - this was bound to happen eventually
    - don't think testing other output formats is necessary since we don't have any specific logic for that, so that is just Rollup behavior
  - take `input` path and rpt2 options as params
    - and add the `tsconfig` as a default
  - add a hacky workaround so that Rollup doesn't output a bunch of warnings in the logs
  - format: use double quotes for strings consistently (my bad, I normally use single quotes in my own repos)

- so we can clean it up after testing to ensure consistency
  - and so we're not filling up the cache in `node_modules` with testing caches

- also add a comment to one the of the tests

- make sure they don't get output when not asked for

- `clean: true` also means that no cache is created
  - which is a bit confusing naming, but was requested by a few users and implemented in f15cb84
  - so have to create the bundle one _more_ time to create the cache
    - note that `tscache`'s `getCached` and `isDirty` functions are now actually covered in the coverage report

- double it bc it was occassionally failing on CI due to timeouts

- ensures that TS understands the JS w/ DTS w/o error
- and that rpt2 filters out JS while Rollup still resolves it on its own (since Rollup understands ESM)
  - similar to testing w/ a different plugin (i.e. literally testing an "integration"), but this is native Rollup behavior in this case where it doesn't need a plugin to understand ESM
- also the first test of actual code contents

- reformat the cache test a bit into its own block since we now have ~3 different sets of tests in the suite

- this doesn't test a new code path and the first test already tests the entire bundle for the fixture, so the other tests just repeat that

- refactor: rename `integration/index.spec` -> `integration/no-errors.spec`
- refactor: split `genBundle` func out into a helper file to be used by multiple integration test suites
  - simplify the `genBundle` within `no-errors` as such

- create new `errors` fixture just with some simple code that doesn't type-check for now
  - add test to check that the exact semantic error pops up
    - and it even tests colors 😮  ...though I was confused for some time why the strings weren't matching... 😐
  - add test to make sure it doesn't pop up when `check: false` or `abortOnError: false`
    - when `abortOnError: false`, detect that a warning is created instead

- due to the new `errors` dir in the fixtures dir, the fixtures `tsconfig` now picks up two dirs
  - which changes the `rootDir` etc
  - so create two tiny `tsconfig`s in both fixture dirs that just extend that one
    - and now tests all run simiarly to before

- this too timed out, probably due to the checks that _don't_ error

- so that Jest can parallelize these
  - CI was timing out on this, so splitting it out should help as it'll be 10s each

- bc it was still timing out in some cases 😕
  - this time the `no-errors` suite was timing out, so just increase all around

- woooops... was wondering why it was `.ts`; turns out because I wrote the `output.file` setting that way 😅 😅 😅

- also add a missing comment in errors for consistency
- and put code checks _after_ file structure checks, since that's a deeper check

- should output declaration and declaration map for file
  - code + declaration should contain the one-line function
  - code _shouldn't_ contain anything from TS files

- since this is plain ESM code, we don't need another plugin to process this
  - nice workaround to installing another plugin that I hadn't thought of till now!

- add a file to `errors` with a syntax error in it
  - apparently this does throw syntax err, but does not cause `emitSkipped: true`... odd...
    - so may need another test for that...
    - `abortOnError: false` / `check: false` both cause Rollup to error out instead
  - rename `errors/index` -> `errors/semantic` since we have different kinds now
  - change the `include` to only take a single file, so that we don't unnecessarily generate declarations or type-check other error files

- refactor(test): rewrite `genBundle` in both files to take a relative path to a file
  - simplifies the `emitDeclarationOnly` test as we can now just reuse the local `genBundle` instead of calling `helpers.genBundle` directly
  - use the same structure for `errors`'s different files as well

- refactor(test): split `errors.spec` into `tsconfig` errors, semantic errors, and syntactic errors (for now)

- add a slightly hacky workaround to get `fs.remove` to not error
  - seems to be a race condition due to the thrown errors and file handles not being closed immediately on throw (seems like they close during garbage collection instead?)
  - see linked issue in the comment; workaround is to just give it some more time
    - not sure that there is a true fix for this, since an improper close may cause indeterminate behavior

- got a Windows error in CI for the `errors` test suite