Storybook Addon Coverage

Tools to support code coverage in Storybook and the Storybook test runner. It supports Storybook projects that use Babel 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:

module.exports = {
  addons: ["@storybook/addon-coverage"],
};

Configuring the addon

This addon instruments your code by using babel-plugin-istanbul if your project uses Babel 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:

module.exports = {
  addons: [
    {
      name: "@storybook/addon-coverage",
      options: {
        istanbul: {
          include: ["**/stories/**"],
        },
      },
    },
  ],
};

The available options if your project uses Babel are as follows:

Option name	Description	Type	Default
cwd	Set the working directory	String	process.cwd()
include	See here for more info	Array<String>	['**']
exclude	See here for more info	Array<String>	list
extension	List of extensions that nyc should attempt to handle in addition to .js	Array<String>	['.js', '.cjs', '.mjs', '.ts', '.tsx', '.jsx', '.vue', '.svelte]
excludeNodeModules	Whether or not to exclude all node_module folders (i.e. /node_modules/) by default	boolean	true
ignoreClassMethods	Class method names to ignore for coverage|Array |[]`
useInlineSourceMaps	Variable to pass sourcemap explicitly	object	-
inputSourceMap	Scope to store the coverage variable	string	-
nycrcPath	Path to nyc config file	string	-
onCover	Hook used to track coverage for all files	(fileName: string, fileCoverage: FileCoverage) => unknown	-
fileName	File name to use in onCover hook	string	-

Note: If you're using typescript, you can import the type for the options like so:

import type { AddonOptionsBabel } 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 mode
• yarn 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 locally
• yarn storybook to run Storybook
• yarn test-storybook --coverage to test coverage report generation

License

MIT