Storybook Addon Coverage
Tools to support code coverage in Storybook and the Storybook test runner. It supports Storybook projects that use Webpack5 or Vite.
Installation
Install this addon by adding the @storybook/addon-coverage
dependency:
yarn add -D @storybook/addon-coverage
And by registering it in your .storybook/main.js
:
export default {
addons: ["@storybook/addon-coverage"],
};
Configuring the addon
This addon instruments your code by using a custom wrapper around istanbul-lib-instrument if your project uses Webpack5 or vite-plugin-istanbul if your project uses Vite. It provides some default configuration, but if you want to add yours, you can do so by setting the options in your .storybook/main.js
:
export default {
addons: [
{
name: "@storybook/addon-coverage",
options: {
istanbul: {
include: ["**/stories/**"],
},
},
},
],
};
The available options if your project uses Webpack5 are as follows:
Option name | Description | Type | Default |
---|
cwd | Set the working directory | String | process.cwd() |
nycrcPath | Path to specific nyc config to use instead of automatically searching for a nycconfig. | string | - |
include | Glob pattern to include files. It has precedence over the include definition from your nyc config | Array<String> | - |
exclude | Glob pattern to exclude files. It has precedence over the exclude definition from your nyc config | Array<String> | defaultExclude in https://github.com/storybookjs/addon-coverage/blob/main/src/constants.ts |
extension | List of supported extensions. It has precedence over the extension definition from your nyc config | Array<String> | ['.js', '.cjs', '.mjs', '.ts', '.tsx', '.jsx', '.vue', '.svelte] |
coverageVariable | The global variable name that Istanbul will use to store coverage results. | string | - |
preserveComments | Indicates whether comments in the code should be preserved during the instrumentation process. | boolean | true |
compact | Controls whether the output of instrumented code is compacted. Useful for debugging when set to false . | boolean | false |
esModules | Determines whether the code to be instrumented uses ES Module syntax. | boolean | true |
autoWrap | When set to true , wraps program code in a function to enable top-level return statements. | boolean | true |
produceSourceMap | If true , instructs Istanbul to produce a source map for the instrumented code. | boolean | true |
sourceMapUrlCallback | A callback function that gets invoked with the filename and the source map URL when a source map is generated. | function | - |
debug | Enables the debug mode, providing additional logging information during the instrumentation process. | boolean | - |
Note:
If you're using typescript, you can import the type for the options like so:
import type { AddonOptionsWebpack } from "@storybook/addon-coverage";
The available options if your project uses Vite are as follows:
Option name | Description | Type | Default |
---|
cwd | Set the working directory | String | process.cwd() |
include | See here for more info | Array<String> or string | ['**'] |
exclude | See here for more info | Array<String> or string | list |
extension | List of extensions that nyc should attempt to handle in addition to .js | Array<String> or string | ['.js', '.cjs', '.mjs', '.ts', '.tsx', '.jsx', '.vue', '.svelte] |
requireEnv | Optional boolean to require the environment variable (defaults to VITE_COVERAGE) to equal true in order to instrument the code. Otherwise it will instrument even if env variable is not set. However if requireEnv is not set the instrumentation will stop if the environment variable is equal to false. | boolean | - |
cypress | Optional boolean to change the environment variable to CYPRESS_COVERAGE instead of VITE_COVERAGE. For ease of use with @cypress/code-coverage coverage | boolean | - |
checkProd | Optional boolean to enforce the plugin to skip instrumentation for production environments. Looks at Vite's isProduction key from the ResolvedConfig. | boolean | - |
forceBuildInstrument | Optional boolean to enforce the plugin to add instrumentation in build mode. | boolean | false |
nycrcPath | Path to specific nyc config to use instead of automatically searching for a nycconfig. This parameter is just passed down to @istanbuljs/load-nyc-config. | string | - |
Note:
If you're using typescript, you can import the type for the options like so:
import type { AddonOptionsVite } from "@storybook/addon-coverage";
Development scripts
yarn start
runs babel in watch modeyarn build
build and package your addon code
To run the examples, choose one of the projects in the examples
directory then run:
yarn
to install dependencies and link the addon locallyyarn storybook
to run Storybookyarn test-storybook --coverage
to test coverage report generation
License
MIT