vue-jest

What is vue-jest?

vue-jest is a Jest transformer for Vue single-file components (SFCs). It allows you to use Jest to test Vue components by transforming the .vue files into a format that Jest can understand.

What are vue-jest's main functionalities?

Transform Vue SFCs

This feature allows Jest to transform Vue single-file components (.vue files) so that they can be tested. The code sample shows how to configure Jest to use vue-jest for transforming .vue files.

module.exports = { transform: { '^.+\.vue$': 'vue-jest' } };

Mocking Vue Components

This feature allows you to mock Vue components and their dependencies during testing. The code sample demonstrates how to use vue-jest with @vue/test-utils to shallow mount a component and mock a translation function.

import { shallowMount } from '@vue/test-utils';
import MyComponent from '@/components/MyComponent.vue';

test('renders a message', () => {
  const wrapper = shallowMount(MyComponent, {
    mocks: {
      $t: msg => msg
    }
  });
  expect(wrapper.text()).toContain('Hello World');
});

Snapshot Testing

This feature allows you to perform snapshot testing on Vue components. The code sample shows how to use vue-jest with @vue/test-utils to create a snapshot of a component's rendered HTML and compare it to a saved snapshot.

import { shallowMount } from '@vue/test-utils';
import MyComponent from '@/components/MyComponent.vue';

test('matches snapshot', () => {
  const wrapper = shallowMount(MyComponent);
  expect(wrapper.html()).toMatchSnapshot();
});

Other packages similar to vue-jest

vue-test-utils

vue-test-utils is the official testing utility library for Vue.js. It provides methods to mount and interact with Vue components in tests. While vue-jest focuses on transforming .vue files for Jest, vue-test-utils provides a more comprehensive set of utilities for testing Vue components.

jest-vue-preprocessor

jest-vue-preprocessor is another Jest transformer for Vue single-file components. It is similar to vue-jest in that it transforms .vue files for Jest, but it is less commonly used and lacks some of the additional features and community support that vue-jest offers.

babel-jest

babel-jest is a Jest transformer that uses Babel to transform JavaScript files. While it is not specific to Vue, it can be used in conjunction with other tools to transform Vue components. It is more general-purpose compared to vue-jest, which is specifically designed for Vue SFCs.

README

vue-jest

Jest Vue transformer with source map support

NOTE: This is documentation for vue-jest@3.x. View the vue-jest@2.x documentation

Usage

npm install --save-dev vue-jest

Setup

To define vue-jest as a transformer for your .vue files, map them to the vue-jest module:

{
  "jest": {
    "transform": {
      "^.+\\.vue$": "vue-jest"
    }
}

A full config will look like this.

{
  "jest": {
    "moduleFileExtensions": [
      "js",
      "json",
      "vue"
    ],
    "transform": {
      "^.+\\.js$": "babel-jest",
      "^.+\\.vue$": "vue-jest"
    }
  }
}

If you're on a version of Jest older than 22.4.0, you need to set mapCoverage to true in order to use source maps.

Example Projects

Example repositories testing Vue components with jest and vue-jest:

• Avoriaz with Jest
• Vue Test Utils with Jest

Supported langs

vue-jest compiles the script and template of SFCs into a JavaScript file that Jest can run. Currently, SCSS, SASS and Stylus are the only style languages that are compiled.

Supported script languages

• typescript (lang="ts", lang="typescript")
• coffeescript (lang="coffee", lang="coffeescript")

Global Jest options

You can change the behavior of vue-jest by using jest.globals.

Tip: Need programmatic configuration? Use the --config option in Jest CLI, and export a .js file

babelConfig

Provide babelConfig in one of the following formats:

• <Boolean>
• <Object>
• <String>

Boolean

• true - Enable Babel processing. vue-jest will try to find Babel configuration using find-babel-config.

This is the default behavior if babelConfig is not defined.

• false - Skip Babel processing entirely:

{
  "jest": {
    "globals": {
      "vue-jest": {
        "babelConfig": false
      }
    }
  }
}

Object

Provide inline Babel options:

{
  "jest": {
    "globals": {
      "vue-jest": {
        "babelConfig": {
          "presets": [
            [
              "env",
              {
                "useBuiltIns": "entry",
                "shippedProposals": true
              }
            ]
          ],
          "plugins": [
            "syntax-dynamic-import"
          ],
          "env": {
            "test": {
              "plugins": [
                "dynamic-import-node"
              ]
            }
          }
        }
      }
    }
  }
}

String

If a string is provided, it will be an assumed path to a babel configuration file (e.g. .babelrc, .babelrc.js).

• Config file should export a Babel configuration object.
• Should not point to a project-wide configuration file (babel.config.js), which exports a function.

{
  "jest": {
    "globals": {
      "vue-jest": {
        "babelConfig": "path/to/.babelrc.js"
      }
    }
  }
}

To use the Config Function API, use inline options instead. i.e.:

{
  "jest": {
    "globals": {
      "vue-jest": {
        "babelConfig": {
          "configFile": "path/to/babel.config.js"
        }
      }
    }
  }
}

tsConfig

Provide tsConfig in one of the following formats:

• <Boolean>
• <Object>
• <String>

Boolean

• true - Process TypeScript files using custom configuration. vue-jest will try to find TypeScript configuration using tsconfig.loadSync.

This is the default behavior if tsConfig is not defined.

• false - Process TypeScript files using the default configuration provided by vue-jest.

Object

Provide inline TypeScript compiler options:

{
  "jest": {
    "globals": {
      "vue-jest": {
        "tsConfig": {
          "importHelpers": true
        }
      }
    }
  }
}

String

If a string is provided, it will be an assumed path to a TypeScript configuration file:

{
  "jest": {
    "globals": {
      "vue-jest": {
        "tsConfig": "path/to/tsconfig.json"
      }
    }
  }
}

Supported template languages

• pug (lang="pug")

  • To give options for the Pug compiler, enter them into the Jest configuration. The options will be passed to pug.compile().

    {
      "jest": {
        "globals": {
          "vue-jest": {
            "pug": {
              "basedir": "mybasedir"
            }
          }
        }
      }
    }
  

• jade (lang="jade")

• haml (lang="haml")

Supported style languages

• stylus (lang="stylus", lang="styl")
• sass (lang="sass")
  • The SASS compiler supports jest's moduleNameMapper which is the suggested way of dealing with Webpack aliases.
• scss (lang="scss")

  • The SCSS compiler supports jest's moduleNameMapper which is the suggested way of dealing with Webpack aliases.

  • To import globally included files (ie. variables, mixins, etc.), include them in the Jest configuration at jest.globals['vue-jest'].resources.scss:

    {
      "jest": {
        "globals": {
          "vue-jest": {
            "resources": {
              "scss": [
                "./node_modules/package/_mixins.scss",
                "./src/assets/css/globals.scss"
              ]
            }
          }
        }
      }
    }
    

• postcss (lang="pcss", lang="postcss")

CSS options

experimentalCSSCompile: Boolean Default true. Turn off CSS compilation hideStyleWarn: Boolean Default false. Hide warnings about CSS compilation resources:

{
  "jest": {
    "globals": {
      "vue-jest": {
        "hideStyleWarn": true,
        "experimentalCSSCompile": true
      }
    }
  }
}