Had Code Coverage Previously, but now Disappeared

[jvanderen1]

🐛 Bug Report

In my test suite, I normally ran all my tests and received some code coverage:

But now I updated npm and node, now my code coverage looks like this:

Reproduction

Visit the following repository: https://gitlab.com/jvanderen1/testing-react-components/-/tree/master

Then run the following commands:

npm install
npm run test:coverage

envinfo

  System:
    OS: macOS 10.15.2
    CPU: (8) x64 Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz
  Binaries:
    Node: 12.13.1 - /usr/local/bin/node
    npm: 6.12.1 - /usr/local/bin/npm
  npmPackages:
    jest: ^24.9.0 => 24.9.0

[jvanderen1]

@jeysal Anymore update's on this issue?

[jeysal]

Don't know more than you, sorry. I get lots of coverage on Node 12.13.1 so that doesn't seem broken in general.

[thecristen]

I might be seeing a similar/related problem. My Jest config specifies a coverageThreshold, and my project suddenly went from meeting all thresholds to not -- despite no change in my project since the last (passing on CI) commit to master.

But, I too updated npm recently, to 6.13.6. So, unlike the OP I do get non-zero coverage results, but they are different (probably invalid) results.

[ThePeach]

I'd like to chime in, as in a newly implemented project I'm getting 0% coverage, and an empty lcov.info file and reports.
configuration is of the likes:

module.exports = {
  setupFiles: ['<rootDir>/jest.setup.js'],
  moduleNameMapper: {
    '^@/(.*)$': '<rootDir>/$1',
    '^~/(.*)$': '<rootDir>/$1',
    '^vue$': 'vue/dist/vue.common.js',
  },
  moduleFileExtensions: ['js', 'vue', 'json'],
  transform: {
    '^.+\\.js$': 'babel-jest',
    '.*\\.(vue)$': 'vue-jest',
  },
  collectCoverage: true,
  collectCoverageFrom: [
    '**/components/**/*.vue',
  ],
  reporters: ['default', 'jest-junit'],
}

Unfortunately I have no previous state to compare it to, but other project with jest 24.9.0 coverage reports is correct (and has basically the same config).

they both are on node 12.14.1 and npm 6.13.4.

[medington]

Update: Turns out the workaround I found was for a regression in Jest, so definitely not relevant. Please ignore this "solution". See #9724

---

Just wanted to share that I was running into this issue as well in a project I work on. In my case, the issue was introduced by adding a transform key to the jest.config.js file.

The key looked like this:

  transform: {
    '^.+\\.(ts|tsx)$': 'ts-jest'
  },

But the project was actually all still just comprised of plain .js files that required no transformation. Removing that key completely, or adding js to the list of transform file extensions resolved the issue. The project in question is part of a monorepo that is mostly all Typescript files and there is a shared jest config file.

There is a note in the Jest docs that eludes to this behavior, but I'm not sure if it really applies in our case because we have never explicitly used `babel-jest':

Note: if you are using the babel-jest transformer and want to use an additional code preprocessor, keep in mind that when "transform" is overwritten in any way the babel-jest is not loaded automatically anymore. If you want to use it to compile JavaScript code it has to be explicitly defined. See babel-jest plugin

[SimenB]

What you have in transform shouldn't make it so you don't have coverage.

This issue needs a reproduction though, not just "it doesn't work"

[jvanderen1]

@SimenB See reproduction steps above

[SimenB]

Seems to be an issue with watch mode, doing npm run test:coverage -- --watchAll works.

You say you updated node and npm then it broke - do you know what versions?

[jvanderen1]

Interesting. The command npm run test:coverage used to work and produced what you see. Now, the command makes:

Here are my most current versions:
node: v13.12.0
npm: 6.14.4

[medington]

@SimenB Turns out the workaround I found was for a regression that was fixed in #9724. My issue was resolved by updating to Jest to 25.2.4. Thanks for the message though!