babel-jest 22.2.0 lowered our coverage significantly

[StephanBijzitter]

Do you want to request a feature or report a bug?
Bug.

What is the current behavior?
Everything works, but our line coverage compared to 22.1.0 is significantly less, without any code or test changes.

What is the expected behavior?
Everything works, and our line coverage remains the same.

Please provide your exact Jest configuration and mention your Jest, node,
yarn/npm version and operating system.
Content of the script used in package.json:

"jest": "jest --coverage --verbose --runInBand"

Content of babel configuration in package.json:

"babel": {
    "presets": [
      "es2015",
      "react",
      "stage-0"
    ],
    "plugins": [
      [
        "module-resolver",
        {
          "root": [
            "./source",
            "./src"
          ]
        }
      ]
    ]
  },

Content of the configuration file:
https://gist.github.com/StephanBijzitter/036140f1b4c8174018bd45c65360077f

Node 8.9.1 and Yarn 1.3.2, OS X & Ubuntu (Windows not tested)

With babel-jest 22.1.0:

With babel-jest 22.2.0:

[SimenB]

This should be fixed #5496. @mjesun mind releasing a patch?

[dstarosta]

I am not sure if this is related. I am seeing duplicate file records in the coverage output. The secondary lines reduce the coverage because they are not reported with 0 coverage.

The strange part is it only happens in Jenkins jobs. The HTML report also has duplicate lines and low coverage. Downgrading Jest to v21 fixes the issue. I am using the --no-cache option.

Here is a partial example:

  ----------------------------------------------------|----------|----------|----------|----------|----------------|
  File                                                |  % Stmts | % Branch |  % Funcs |  % Lines |Uncovered Lines |
  ----------------------------------------------------|----------|----------|----------|----------|----------------|
  All files                                           |    27.32 |    34.66 |    39.49 |    27.55 |                |
   src                                                |    33.33 |      100 |      100 |    33.33 |                |
    auth-functions.js                                 |      100 |      100 |      100 |      100 |                |
    auth-functions.js                                 |        0 |      100 |      100 |        0 |            3,6 |
   src/actions                                        |    40.17 |       50 |       50 |    39.66 |                |
    authorization-actions.js                          |      100 |      100 |      100 |      100 |                |
    authorization-actions.js                          |        0 |      100 |        0 |        0 |... 46,57,69,80 |
    layout-actions.js                                 |      100 |      100 |      100 |      100 |                |
    layout-actions.js                                 |        0 |      100 |        0 |        0 |... 2,83,96,108 |
    unit-history-actions.js                           |      100 |      100 |      100 |      100 |                |
    unit-history-actions.js                           |        0 |        0 |        0 |        0 |... 83,87,88,90 |

[msholty-fd]

If you're running into this issue without changing your jest version, set "retainLines": true in your repo's .babelrc. I'm not 100% sure of the implications but from the documentation it appears it's just a line number thing for sourcemaps?

[dstarosta]

"retainLines": true in the .baberc did not fix my issue.

[SimenB]

Oh, if adding retainLines didn't help, then it's another issue... Are you able to create a reproduction case?

[dstarosta]

The problem is it only happens when the build process is running on Jenkins build server.

I think i have the same issue here on Windows 10.
It only happens in libs\gates...

PASS libs\shared\src\pipes\key-value.pipe.spec.ts
PASS libs\shared\src\statemanagement\reducers\full-screen.spec.ts
PASS libs\gates\src\services\gates.service.spec.ts
FAIL libs\gates\src\services\gates.service.spec.ts
● Test suite failed to run

No file coverage available for: C:\Bert\fe\fe-parts\libs\gates\src\services\gates.service.ts
  
  at CoverageMap.fileCoverageFor (node_modules/istanbul-lib-coverage/lib/coverage-map.js:96:15)
      at Array.forEach (<anonymous>)

PASS libs\gates\src\containers\create-gate\create-gate.component.spec.ts
FAIL libs\gates\src\containers\create-gate\create-gate.component.spec.ts
● Test suite failed to run

No file coverage available for: C:\Bert\fe\fe-parts\libs\gates\src\services\gates.service.ts
  
  at CoverageMap.fileCoverageFor (node_modules/istanbul-lib-coverage/lib/coverage-map.js:96:15)
      at Array.forEach (<anonymous>)

[StephanBijzitter]

@BertDuyck seems to be a different issue, because my issue doesn't produce any errors.

[SimenB]

@StephanBijzitter Is it still an issue with the latest version of Jest? If yes, can you set up a reproduction case so we can debug?

@BertDuyck I wonder if your issue is related to #5428?

@SimenB It only happens in one lib, while i have other libs generated the same way with no duplicates.
A workaround for me is to run jest with --no-cache.

[SimenB]

Without a reproduction, this is not actionable. Please test with Jest 24 (which has upgraded babel and istanbul dependencies). If it's still an issue, open up a new issue (with a reproduction)

[github-actions]

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