Coverage Remapping Issue

[Aftabnack]

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

Unsure Feature

What is the current behavior?

• Coverage remapping that happens in html lcov-report that gets generated is onto the actual file contents. Need to be able to remap it onto tranformed version of the actual file content.

• This is my scenario
  

Relevant Preprocessor code

const babelOpts = Object.assign({}, babelConf, {
    plugins: (babelConf && babelConf.plugins) || [],
    presets: ((babelConf && babelConf.presets) || []).concat([jestPreset]),
    retainLines: true,
    sourceMaps: 'inline'
});

module.exports = {
    process(src, filename, config, transformOptions) {
        src = transformJustPhnx(src, true); //Conversion of abstraction syntax to React Code
        const finalOpts = Object.assign(
            {
                filename
            },
            babelOpts
        );
        if (transformOptions && transformOptions.instrument) {
            finalOpts.auxiliaryCommentBefore = ' istanbul ignore next ';
            // Copied from jest-runtime transform.js
            finalOpts.plugins = finalOpts.plugins.concat([
                [
                    babelIstanbulPlugin,
                    {
                        cwd: config.rootDir,
                        exclude: []
                    }
                ]
            ]);
        }

        const transformResult = babelTransform(src, finalOpts); //React code to final output with Sourcemaps.
        return transformResult ? transformResult.code : src;
    },
    canInstrument: true
};

Current output in lcov-report

Report that is achieved by superimposing it on the intermediate (Currently doing this when running SonarQube on the code)

What is the expected behavior?

• Need to be able to remap it onto the intermediate output of my Jest Preprocessor transformations.

Please provide your exact Jest configuration and mention your Jest, node,

yarn/npm version and operating system.

• Jest : 22.0.1
• Ubuntu 17.10
• Node 8.6.0
• npm 5.6.0

[Aftabnack]

• After doing a little digging myself, found out where exactly to add this to get this to work.
• This is where the source code gets read for the report.

---

• I have tested adding my transformation of the source after that line. It works perfectly.

---

• Now only question remains, is this a valid expectation to provide for sourcecode transformation? If so how do I go about adding a PR for this? Raising a thread on https://github.com/istanbuljs/istanbuljs too

[SimenB]

I think being able to say "this is the source code I want instrumented" makes sense.

Are you saying that the fix to your problem must be in Istanbul? There's no change we can make?

[Aftabnack]

• I initially thought that the issue is with Jest, since I was seeing the same thing in error code frame.
• The fix for the coverage report is in Istanbul, but the error code frame I need to investigate further.
• The fix is needed for error code frame too, which I suspect would be from jest itself.
• If it gets added to Istanbul, then the transform for the source code will be an external config. That config for that needs to be allowed to be passed from jest.

[SimenB]

We have #5121 for sourcemaps from transforms, I guess the Jest side can be folded into that?

[Aftabnack]

My understanding of source maps are very basic. If you are saying the error code frame can be picked up from the source maps then yes, that's what I am asking for! 😄

[SimenB]

We should. I'll close this as a dupe, but leave a note over there to test this use case whenever we get around to fixing it. If it does not fix it, we can reopen.

Thanks for the detailed issue and detective work!

[github-actions]

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