Vue SFCs not included in coverage reports

Problem

I’m using vue-test-utils with Jest to run unit tests for single-file Vue components. I’m relying on vue-jest to transform the component files so that I don’t have to rely on Webpack, etc.

I’m able to require Vue components in tests and run them without any problems, but for some reason I’m not able to get Jest to include these files in the coverage reports that it generates.

I’m using Jest at 25.1.0, vue-jest at 3.0.5, and vue at 2.6.11.

One other thing I should note: for this project, my Vue components are all written in ES5 (plus module.exports and require statements; I’m relying on a non-JS module tool to deliver this code in browser). I’m not running any webpack or babel transformations on JS code either at runtime or in testing, just the vue-jest transform for SFCs. Everything works fine until it comes to generating the coverage report.

Source code is visible here: https://github.com/egardner/mediawiki-extensions-VueTest

Configuration

All JS/Vue files live in a resources folder which is structured like this:

resources/
├── components
│   ├── ApiRequestModule.vue
│   ├── App.vue
│   ├── ChildComponent.vue
│   ├── ComputedPropertyModule.vue
│   ├── ParentChildCommunicationModule.vue
│   ├── TwoWayBindingModule.vue
│   └── index.js
├── init.js
└── plugins
    ├── api.js
    ├── i18n.js
    └── index.js

Here are the relevant parts of the Jest configuration being used:

module.exports = {
  clearMocks: true,
  collectCoverage: true,
  collectCoverageFrom: [
    "resources/**/*.(js|vue)"
  ],
  coverageDirectory: "coverage",
  coveragePathIgnorePatterns: [,
    "/node_modules/",
    "resources/components/index.js",
    "resources/plugins/index.js",
    "resources/init.js"
  ],
  globals: {
    "vue-jest": {
      babelConfig: false,
      hideStyleWarn: true,
      experimentalCSSCompile: true
    }
  },
  moduleFileExtensions: [
    "js",
    "json",
    "vue"
  ],
  setupFiles: [
    "./jest.setup.js"
  ],
  transform: {
    ".*\\.(vue)$": "<rootDir>/node_modules/vue-jest"
  },
};

Output

When I run the tests using Jest, I get output like this:

 PASS  tests/jest/ChildComponent.test.js
 PASS  tests/jest/TwoWayBindingModule.test.js
 PASS  tests/jest/ComputedPropertyModule.test.js
 PASS  tests/jest/App.test.js
 PASS  tests/jest/ApiRequestModule.test.js
 PASS  tests/jest/ParentChildCommunictionModule.test.js
----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------|---------|----------|---------|---------|-------------------
All files |   92.86 |    66.67 |     100 |   92.86 |
 api.js   |     100 |      100 |     100 |     100 |
 i18n.js  |   88.89 |       50 |     100 |   88.89 | 52
----------|---------|----------|---------|---------|-------------------

Test Suites: 6 passed, 6 total
Tests:       13 passed, 13 total
Snapshots:   0 total
Time:        3.981s
Ran all test suites.

The tests (which require various Vue files) run and succeed, but the coverage report only includes the plain JS files.

Do Vue files need to be transformed with Webpack or Babel so that they can be assessed for coverage in Jest? I had assumed that the vue-jest transformations would allow for this.

[ThePeach]

And then running npx vue-cli-service test:unit

so that version of vue-cli-service seems to be using jest 24.9.0

I have exactly the same problem this post is talking about and I was running 25.1.0

Downgraded to 24.9.0 and coverage started working again. So major update of jest is breaking something with the vue-jest reporting.

[egardner]

@TerminalSpirit this is useful, thank you for sharing. It seems like vue-cli-service knows some tricks that we don’t! I don’t understand what the relevant config differences are, but I was able to get coverage reports by doing the following:

Adding these packages to package.json (I didn’t need the babel plugin)

"@vue/cli-plugin-unit-jest": "4.2.2",
"@vue/cli-service": "4.2.2",

And then running npx vue-cli-service test:unit

That gives me the following report:

-------------------------------------|----------|----------|----------|----------|-------------------|
File                                 |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
-------------------------------------|----------|----------|----------|----------|-------------------|
All files                            |    96.97 |    66.67 |      100 |    96.97 |                   |
 components                          |      100 |      100 |      100 |      100 |                   |
  ApiRequestModule.vue               |      100 |      100 |      100 |      100 |                   |
  App.vue                            |      100 |      100 |      100 |      100 |                   |
  ChildComponent.vue                 |      100 |      100 |      100 |      100 |                   |
  ComputedPropertyModule.vue         |      100 |      100 |      100 |      100 |                   |
  ParentChildCommunicationModule.vue |      100 |      100 |      100 |      100 |                   |
  TwoWayBindingModule.vue            |      100 |      100 |      100 |      100 |                   |
 plugins                             |    92.86 |    66.67 |      100 |    92.86 |                   |
  api.js                             |      100 |      100 |      100 |      100 |                   |
  i18n.js                            |    88.89 |       50 |      100 |    88.89 |                52 |
-------------------------------------|----------|----------|----------|----------|-------------------|

This is a decent solution for now but I’d still love to understand what options are actually being provided to Jest here that suddenly allows everything to work properly…