Jest: Allow multiple --testResultsProcessor options

[segrey]

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

What is the current behavior?

Run jest tests passing two --testResultsProcessor options:

./node_modules/jest/bin/jest.js --testResultsProcessor=./processorA.js --testResultsProcessor=./processorB.js

Error:

● Validation Error:

  Module ./processorA.js,./processorB.js in the testResultsProcessor option was not found.

What is the expected behavior?

Both results processors are called back.

Please provide your exact Jest configuration and mention your Jest, node, yarn/npm version and operating system.

jest: 21.0.2
node: 8.4.0
yarn: 1.0.0
OS: Linux Mint

[segrey]

Having such a feature would allow tools to implement jest integration using --testResultsProcessor and not worry about overwriting user-specified --testResultsProcessor.
E.g. currently WebStorm uses --setupTestFrameworkScriptFile for its jest integration. Well, it turned out to be not great (need to add IDE sources to transformIgnorePatterns and unmockedModulePathPatterns). Using jest-editor-support is too much as IDE needs TestResults only (also parent test suites are missing there for some reason). Seems tests results passed to test results processor (--testResultsProcessor) fit perfectly.

[cpojer]

I don't think this needs to change. You can simply have a testResultsProcessor that wraps other test results processors:

module.exports = results => processA(processB(results));

that seems much more straightforward to me. What do you think?

[segrey]

@cpojer Yeah, delegation is a good approach (I thought about it and should have mentioned it, sorry). It will work, however, it has a downside: a tool has to run jest with --showConfig first to find out user-specified testResultsProcessor. It may take ~0.5 second to complete and might be annoying.
Since it's needed for tools, I'd be glad to work on a PR if this issue gets accepted.

[cpojer]

I'm fine with a PR that turns this option into a string or array value instead of just string.

[cpojer]

The thing to consider though is that the ordering may matter: the results processors may return any object that may not be the same one as before, it may have less information that the next processor expects.

[juhamust]

Continuing what @cpojer already said: Combine test results processors using custom one:
http://wookieb.pl/multiple-testresultsprocessors-with-jest/

However, it would be nice if testResultsProcessor would accept an array

[cpojer]

I'm gonna close this as composition solves this problem for now.

[manuc66]

The link provided by @juhamust is now only accessible from https://web.archive.org/web/20171113152502/http://wookieb.pl/multiple-testresultsprocessors-with-jest/

[juhamust]

Copied the solution from http://wookieb.pl/multiple-testresultsprocessors-with-jest/ here:

Create resultsProcessor.js file with the following content

module.exports = function() {  
    require('../node_modules/ts-jest/coverageprocessor').apply(this, arguments);
    return require('../node_modules/jest-junit').apply(this, arguments);
    // add any other processor you need
};

Remember to update package.json too

{
   "jest": {
        "testResultsProcessor": "./resultsProcessor"
   }
}

[meza]

Streamlined it a bit here: https://www.npmjs.com/package/jest-multiple-result-processors