task "combineCoverage" times out for big projects

I have a project with 424 instrumented source files.

The task “combineCoverage” allways runs into a timeout (even after waiting for 2h30).

After some digging:

I added some debug in the following code:

https://github.com/cypress-io/code-coverage/blob/40a602d4b26a22b28ced552e7829a27f38a2cebc/support.js#L17-L29

• I found out that my win.__coverage__ contains a huge object (with 424 entries) that serializes to a 7.5MB string.

• The combineCoverage task is never reached (I added a debug at the beginning and it never prints).

• I created an empty task testTask which I called using the same object as parameter and it also got stuck.

• when I only instrument 3 files, it works fine.

my workaround

As a workaround, I’m currently ‘splitting’ my coverage object into smaller chunks (50 entries each). And it works fine.

  afterEach(() => {
    // save coverage after each test
    // because the entire "window" object is about
    // to be recycled by Cypress before next test
    cy.window().then(win => {
      // if application code has been instrumented, the app iframe "window" has an object
      const applicationSourceCoverage = win.__coverage__

      if (applicationSourceCoverage) {
        let i = 0;
        let tmpObj = {};
        Object.keys(applicationSourceCoverage).forEach(key => {
          let value = applicationSourceCoverage[key];
          tmpObj[key] = value;
          if (++i % 50 == 0) {
            cy.log(i + ' - ' + JSON.stringify(tmpObj).length);
            cy.task('combineCoverage', tmpObj)
            tmpObj = {};
          }
        });
        if (tmpObj !== {}) {
          cy.log(i + ' - ' + JSON.stringify(tmpObj).length);
          cy.task('combineCoverage', tmpObj)
        }
      }
    })
  })

it works fine as a temporary woraround:

[bahmutov]

🎉 This issue has been resolved in version 1.10.2 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[lynchem]

Thanks for that. I was able to follow that commit and get ours working much quicker now as well.