Incomplete coverage caused by `filterSpecsFromCoverage`

[skimi]

Versions

• What is this plugin's version? 3.4.2 (but they all have the issue)
• What is your operating system? linux / mac (all fail)
• What is the shell? bash, zsh, all fail
• What is the Node version? 12
• What is the NPM version? 6
• How do you instrument your application? babel-istanbul-plugin
• When running tests, if you open the web application in regular browser, and open DevTools, do you see window.__coverage__ object? Can you paste a screenshot? yes the coverage is correct at that point

Describe the bug

The function filterSpecsFromCoverage https://github.com/cypress-io/code-coverage/blob/master/support-utils.js#L9 can ignore files that are not spec when using a testFiles glob that is not the default **/*.*.

Let's say I have a glob testFiles: "**/billing/*.js" and my project has the following structure:

cypress
  - integration
    - billing
      my-billing.spec.js
src
  - billing
    MyBill.js

Cypress runs the test my-billing.spec.js correctly but in the coverage report MyBill.js is not there.

This is because filterSpecsFromCoverage applies the testFiles glob to any file, even those that are not within the cypress integration folder so my src/billing/MyBill.js is filtered out.

fix

In my project I'm reverting to only use the default value of cypress testFiles but in this repo the fix seems pretty simple. filterSpecsFromCoverage should only filter files that are in the integration folder