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javascriptcode-coverageistanbulnyc
Evil_Transistor
Evil_Transistor

Reputation: 378

How can I use __coverage__ global object generated by istanbul to get code coverage report?

I'm using istanbul to know what lines of code were executed when I perform an operation on my web app. In order to do this I first instrumented the code using: npx nyc instrument

Then I deployed this code and did my testing. This generated a __coverage__ global object that I have copied into ./.nyc_output/coverage.json

To get the code coverage report, I tried npx nyc report --reporter=html --report-dir=./coverage

However on opening the resultant html file, I see it's empty: index.html

What can I do to fix this?

Upvotes: 2

Views: 445

Answers (1)

Jean Claveau
Jean Claveau

Reputation: 1471

I had a similar issue and it was due to Nyc options: In a monorepo I was trying to get the coverage of files from another package.

- monorepo
  - apps
    - package_1 
      - node webapp.js (using the content instrumented of package_2 )
    - package_2
      - dist
        -  build.js (instrumented with Istambul)

The first thing to check is that the .json files in .nyc_output have the expected coverage content.

If it is, you may move the cwd entry of Nyc options like me:

// monorepo/apps/package_1/nyc.config.js
export default {
  cwd: `${process.cwd()}/../../`,  // targetting the monorepo root
  reportDir: `${process.cwd()}/coverage/backend`,
  tempDir: `${process.cwd()}/.nyc_output`,
}

// process.cwd() is monorepo/apps/package_1

Then nyc report worked like a charm

Upvotes: 0

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