`.nyc_output/out.json` is an empty object when using with `@cypress/react`

Logs and screenshots Please provide debug logs by running Cypress from the terminal with DEBUG=code-coverage environment variable set, see the Debugging section of the README file.

Debug logs

  code-coverage reset code coverage in interactive mode +0ms
  code-coverage parsed sent coverage +32ms
  code-coverage wrote coverage file /Users/chrisrzhou/Github/cypress-coverage-repo/.nyc_output/out.json +1ms
  code-coverage parsed sent coverage +25ms
  code-coverage wrote coverage file /Users/chrisrzhou/Github/cypress-coverage-repo/.nyc_output/out.json +0ms
⚠️ file /Users/chrisrzhou/Github/cypress-coverage-repo/.nyc_output/out.json has no coverage information
Did you forget to instrument your web application? Read https://github.com/cypress-io/code-coverage#instrument-your-application
  code-coverage ⚠️ file /Users/chrisrzhou/Github/cypress-coverage-repo/.nyc_output/out.json has no coverage information +8s
  code-coverage ⚠️ file /Users/chrisrzhou/Github/cypress-coverage-repo/.nyc_output/out.json has no coverage information +1ms
  code-coverage calling NYC reporter with options { 'report-dir': '/Users/chrisrzhou/Github/cypress-coverage-repo/coverage', reporter: [ 'lcov', 'clover', 'json', 'json-summary' ], extension: [ '.js', '.cjs', '.mjs', '.ts', '.tsx', '.jsx' ], excludeAfterRemap: false, 'temp-dir': '/Users/chrisrzhou/Github/cypress-coverage-repo/.nyc_output', tempDir: '/Users/chrisrzhou/Github/cypress-coverage-repo/.nyc_output', reportDir: '/Users/chrisrzhou/Github/cypress-coverage-repo/coverage' } +7ms
  code-coverage current working directory is /Users/chrisrzhou/Github/cypress-coverage-repo +0ms
  code-coverage after reporting, returning the report folder name /Users/chrisrzhou/Github/cypress-coverage-repo/coverage +40ms
  code-coverage Final coverage in /Users/chrisrzhou/Github/cypress-coverage-repo/coverage/coverage-final.json +0ms
  code-coverage There are 0 key(s) in /Users/chrisrzhou/Github/cypress-coverage-repo/coverage/coverage-final.json +0ms

Versions

• What is this plugin’s version? @cypress/code-coverage@3.9.7 (latest)
• What is Cypress version? cypress@7.6.0, @cypress/react@5.9.1, @cypress/webpack-dev-server@1.4.0 (see package.json in repo for more details).
• What is your operating system? Mac
• What is the shell? zsh
• What is the Node version? v12.22.1
• What is the NPM version? 6.14.12
• How do you instrument your application? Through the official docs’ recommendation. See repo below for details.
• When running tests, if you open the web application in regular browser, and open DevTools, do you see window.__coverage__ object? Following the official docs, I can see window.__coverage__ object for the files that the test is touching.
• Is there .nyc_output folder? Is there .nyc_output/out.json file. Is it empty? Both folder and file exists, the contents is just the empty object {}.
• Do you have any custom NYC settings in package.json (nyc object) or in other NYC config files No
• Do you run Cypress tests in a Docker container? No, just locally

Describe the bug

Bug Report

Repro Link

https://github.com/chrisrzhou/cypress-code-coverage-issue-472

Context

It is a minimal example with the following requirements:

• Is an ESM module
  • i.e. "type": "module" is explicitly marked in the package.json
  • appropriate Cypress files need to be marked as .cjs in order for the tests to run. In cypress/plugins/index.cjs and fields in cypress.json.
• Uses component testing (i.e. @cypress/react and using open-ct and run-ct test runners).
• Uses code coverage (i.e. @cypress/code-coverage and babel-plugin-istanbul based on the official docs for instrumentation).

The requirements above are needed in the actual bug faced in the project, so the repo is capturing the minimal configuration of reproducing the same bug.

Reproduce

npm i
npm test

The test runner runs fine, and tests the code correctly.

Expected Behavior

Code coverage to output something meaningful in .nyc_output/out.json

Actual Behavior

.nyc_output/out.json is an empty object. The test runner complains that the code is not instrumented.

[VaibhavP17]

Is there any update on this issue ? I am facing the same issue. While running the application using dev server on regular browser, I see window.__coverage__ object but while running the cypress test cases, I get the errors: cypress\.nyc_output\out.json has no coverage information and "Could not find any coverage information in your application by looking at the window coverage object. Did you forget to instrument your application? See [code-coverage#instrument-your-application](https://github.com/cypress-io/code-coverage#instrument-your-application) [@cypress/code-coverage]"

[namespace-github]

Hello @chrisrzhou, hello all,

here is my solution, which from my point of view is a gap in the documentation.

In my case when using the new component tests, which was mentioned in the context of the question (open-ct or run-ct) window.__coverage__ was not evaluated from @cypress/code-coverage.

The reason was that, according to the documentation, import '@cypress/code-coverage/support'; only included in support/index.js. Cypress, however, uses in my environement instead /support/unit.js for component tests. Both support/index.js and support/unit.js files imports the support/commands.js.

I put the line there, then it works as well, because cypress can register the tasks in component tests.