v8 coverage crashes with type-only files

[nstepien]

🐛 Bug Report

With coverageProvider: 'v8' and coverage enabled, Jest crashes with imported but non-elided type-only modules.

To Reproduce

Steps to reproduce the behavior:

• jest.config.mjs:

  export default {
    collectCoverage: true,
    coverageProvider: 'v8',
    rootDir: 'src'
  };

• babel.config.json

  {
    "presets": [
      "@babel/typescript"
    ]
  }

• src/types.ts:

  export interface obj {}

• src/mytest.test.ts:

  import * as types from './types';
  
  test('1+1=2', () => {
    console.log(types);
    expect(1 + 1).toBe(2);
  });

• Run npx jest

  PASS  src2/mytest.test.ts
    √ 1+1=2 (16 ms)
  
    console.log
      { default: {} }
  
        at Object.<anonymous> (mytest.test.ts:4:11)
  
  TypeError: Cannot read property 'replace' of undefined
      at V8ToIstanbul._resolveSource (D:\repo\node_modules\v8-to-istanbul\lib\v8-to-istanbul.js:86:29)
      at V8ToIstanbul.load (D:\repo\node_modules\v8-to-istanbul\lib\v8-to-istanbul.js:57:26)
      at D:\repo\node_modules\@jest\reporters\build\CoverageReporter.js:624:27
      at Array.map (<anonymous>)
      at CoverageReporter._getCoverageResult (D:\repo\node_modules\@jest\reporters\build\CoverageReporter.js:587:32)
      at CoverageReporter.onRunComplete (D:\repo\node_modules\@jest\reporters\build\CoverageReporter.js:231:45)
      at ReporterDispatcher.onRunComplete (D:\repo\node_modules\@jest\core\build\ReporterDispatcher.js:88:9)
      at TestScheduler.scheduleTests (D:\repo\node_modules\@jest\core\build\TestScheduler.js:350:5)
      at runJest (D:\repo\node_modules\@jest\core\build\runJest.js:376:19)
      at _run10000 (D:\repo\node_modules\@jest\core\build\cli\index.js:416:7)
  

Expected behavior

Jest doesn't crash, and coverage works.

Link to repl or repo (highly encouraged)

envinfo

  System:
    OS: Windows 10 10.0.19042
    CPU: (64) x64 AMD Ryzen Threadripper 3970X 32-Core Processor
  Binaries:
    Node: 15.2.0 - C:\Program Files\nodejs\node.EXE
    npm: 7.0.8 - C:\Program Files\nodejs\npm.CMD
  npmPackages:
    jest: ^26.6.3 => 26.6.3

[SimenB]

Thanks for the report @nstepien!

@bcoe ideas? I haven't dug into it from Jest's side, might be us sending faulty data

[nstepien]

From what I've seen debugging this a little bit, it seems like the type-only module is empty, so the sourcemap is empty/missing, and that empty/missing sourcemap is sent to v8-to-istanbul, which expects populated sourcemap metadata.

[SimenB]

This is what we pass

{
  originalSource: 'export interface obj {}\n\n',
  source: '"use strict";\n' +
    '//# sourceMappingURL=data:application/json;charset=utf-8;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbXSwibmFtZXMiOltdLCJtYXBwaW5ncyI6IiIsInNvdXJjZXNDb250ZW50IjpbXX0=',
  sourceMap: {
    sourcemap: {
      version: 3,
      sources: [],
      names: [],
      mappings: '',
      sourcesContent: []
    }
  }
}

Seems like a bug in v8-to-istanbul to me. We pass a valid sourcemap - it's just empty

[nstepien]

@SimenB Thanks!

[SimenB]

v8-to-istanbul should not rely on file being there - it's optional: https://github.com/mozilla/source-map/blob/0.5.7/README.md#new-sourcemapconsumerrawsourcemap

Not sure what ti should do though - probably fallback to scriptPath which is what my change does in practice

[viceice]

I see this issue again with latest versions, see istanbuljs/v8-to-istanbul#134

[SimenB]

Using jest@next?

[viceice]

No, we are using 26.6.3. It's only fixed in next ?

https://github.com/renovatebot/renovate/blob/9ed77a7c1f8c1915d71e46f6de9b6495c947c053/package.json#L238

[SimenB]

#10819 is only available in next, yes.

Good to fix in istanbul of course, then you'd be able to use 26 👍

[viceice]

Yeah, using patch-package until istanbuljs/v8-to-istanbul#135 is merged 🎉

Any timeframe for next jest version?

[SimenB]

Hoping this month, but I've not had much time for OSS these last few months

[bcoe]

Just merged @viceice's patch 👌 sorry for the nuisance.

[SimenB]

Thanks @bcoe!

[github-actions]

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