feat(typescript): Disable type checking

[nicojs]

Disable type checks by inserting // @ts-nocheck and removing all other // @ts-xxx directives.

It can be configured with:

{
  "disableTypeChecks": "{test,src,lib}/**/*.{js,ts,jsx,tsx,html,vue}" // configure a pattern or `false` here
  "warnings": {
    "preprocessorErrors": true // enable/disable error logging here (default: true)
  }
}

You can disable it completely by setting disableTypeChecks to false. The default is "{test,src,lib}/**/*.{js,ts,jsx,tsx,html,vue}".

The disabling of type checks is done in the DisableTypeChecksPreprocessor class. It calls the function in the instrumenter package to do the actual disabling. The reason for this is that files need to be parsed to distinguish between code and comments (@ts-xxx directives are only removed when they appear inside comments). It also works with HTML and vue files, so it also supports use cases where type checking is done inside vue files (with the vue-cli).

Whenever parsing a file results in an error, a warning is logged and mutation testing will still proceed. The warning can be disabled by setting warnings.preprocessorErrors to false.

This setting replaces both sandbox.fileHeaders and sandbox.stripComments, since those resulted in a lot of problems (see #2438 ).

Fixes #2438

[brodycj]

• Can you add a link to issue Discussion: TypeScript compile errors with mutation switching #2438 to the description of this PR?
• I assume you will remove the other sandbox options from the schema and update the documentation?
• This looks like an empty file on GitHub: packages/core/test/unit/sandbox/disable-type-checking-preprocessor.spec.ts
• I left a couple more comments on the changes

[nicojs]

@brodybits Everything is now ready for review, please have a look 👍

[brodycj]

@nicojs I did take a quick look earlier today, may need some more time to take a more careful look. Thanks for your work so far on this!

[nicojs]

I have second doubts about this default. It might be too broad. For example, when running Stryker on express you get this warning:

18:36:16 (20065) WARN DisableTypeCheckingPreprocessor Unable to disable type checking for file "/home/nicojs/stryker/perf/test/express/examples/ejs/views/footer.html". Shouldn't type checking be disabled for this file? Consider configuring a more restrictive "sandbox.disableTypeChecking" settings (or turn it completely off with `false`) ParseError: Parse error in /home/nicojs/stryker/perf/test/express/examples/ejs/views/footer.html (1:0) Unexpected closing tag "body". It may happen when the tag has already been closed by another tag. For more info see https://www.w3.org/TR/html5/syntax.html#closing-elements-that-have-implied-end-tags
    at ngHtmlParser (/home/nicojs/stryker/perf/test/express/node_modules/@stryker-mutator/instrumenter/dist/src/parsers/html-parser.js:51:15)
    at async Object.parse (/home/nicojs/stryker/perf/test/express/node_modules/@stryker-mutator/instrumenter/dist/src/parsers/html-parser.js:33:18)
    at async DisableTypeCheckingPreprocessor.disableTypeChecking [as impl] (/home/nicojs/stryker/perf/test/express/node_modules/@stryker-mutator/instrumenter/dist/src/disable-type-checking.js:16:17)
    at async /home/nicojs/stryker/perf/test/express/node_modules/@stryker-mutator/core/src/sandbox/disable-type-checking-preprocessor.js:30:32
    at async Promise.all (index 36)
    at async DisableTypeCheckingPreprocessor.preprocess (/home/nicojs/stryker/perf/test/express/node_modules/@stryker-mutator/core/src/sandbox/disable-type-checking-preprocessor.js:27:30)
    at async MultiPreprocessor.preprocess (/home/nicojs/stryker/perf/test/express/node_modules/@stryker-mutator/core/src/sandbox/multi-preprocessor.js:14:25)
    at async MutantInstrumenterExecutor.execute (/home/nicojs/stryker/perf/test/express/node_modules/@stryker-mutator/core/src/process/2-MutantInstrumenterExecutor.js:24:23)
    at async Stryker.runMutationTest (/home/nicojs/stryker/perf/test/express/node_modules/@stryker-mutator/core/src/Stryker.js:32:44)
18:36:16 (20065) WARN DisableTypeCheckingPreprocessor (disable "warnings.preprocessorErrors" to ignore this warning

Maybe a better default would be {test,src,lib}/**/*.{js,ts,jsx,tsx,html,vue}?

[nicojs]

I've implemented this.

[nicojs]

@brodybits I'll be merging this as soon as the tests pass, since it is blocking some progress on other stuff. Feel free to still finish you're review and comment (or again a PR), we can always improve later 🙏

[brodycj]

I would probably rename the option (and ideally the modules) to disableTypeCheck or disableTypeChecks.

My apologies for the delays.

[brodycj]

Thanks! Will you also rename the modules?

[nicojs]

Excellent point! Much better. Thanks a lot! And just in time for this PR 👍

Thanks! Will you also rename the modules?

Yeah, forgot about that at first, did that right after. We're doing squash merges, so it will look nice and tidy afterward ;)

My apologies for the delays.

No worries whatsoever. I'm not entitled to your time, I know that there are more important things than this in the world 🤗

Thank you for the review! I'm glad you find naming things just as important as we do 👍