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https://github.com/cypress-io/code-coverage
Saves the code coverage collected during Cypress tests
https://github.com/cypress-io/code-coverage
code-coverage cypress cypress-plugin
Last synced: 2 months ago
JSON representation
Saves the code coverage collected during Cypress tests
- Host: GitHub
- URL: https://github.com/cypress-io/code-coverage
- Owner: cypress-io
- License: mit
- Created: 2019-05-15T20:31:18.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2024-04-13T12:24:36.000Z (6 months ago)
- Last Synced: 2024-04-14T08:35:36.996Z (6 months ago)
- Topics: code-coverage, cypress, cypress-plugin
- Language: JavaScript
- Homepage:
- Size: 23.1 MB
- Stars: 412
- Watchers: 31
- Forks: 106
- Open Issues: 106
-
Metadata Files:
- Readme: README.md
- License: LICENSE.md
- Support: support-utils.js
Awesome Lists containing this project
README
# @cypress/code-coverage [![renovate-app badge][renovate-badge]][renovate-app] [](https://circleci.com/gh/cypress-io/code-coverage)
> Saves the code coverage collected during Cypress tests
## Install
```shell
npm install -D @cypress/code-coverage
```
**Note:** This plugin assumes that `cypress` is a peer dependency already installed in your project.
Then add the code below to the `supportFile` and `setupNodeEvents` function.
```js
// cypress/support/e2e.js
import '@cypress/code-coverage/support'
```
```js
// cypress.config.js
const { defineConfig } = require('cypress')
module.exports = defineConfig({
// setupNodeEvents can be defined in either
// the e2e or component configuration
e2e: {
setupNodeEvents(on, config) {
require('@cypress/code-coverage/task')(on, config)
// include any other plugin code...
// It's IMPORTANT to return the config object
// with any changed environment variables
return config
},
},
})
```
## Instrument your application
This plugin **DOES NOT** instrument your code. You have to instrument it yourself using the [Istanbul.js](https://istanbul.js.org/) tool. Luckily, it is not difficult. For example, if you are already using Babel to transpile, you can add [babel-plugin-istanbul](https://github.com/istanbuljs/babel-plugin-istanbul) to your `.babelrc` and instrument on the fly.
```json
{
"plugins": ["istanbul"]
}
```
Please see the [Test Apps](#internal-test-apps) section below. You can find a linked project matching your situation to see how to instrument your application's source code before running end-to-end tests to get the code coverage.
If your application has been instrumented correctly, you should see additional counters and instructions in the application's JavaScript resources, as the image below shows.
You should see the `window.__coverage__` object in the "Application under test iframe"
If you have instrumented your application's code and see the `window.__coverage__` object, then this plugin will save the coverage into the `.nyc_output` folder and will generate reports after the tests finish (even in the interactive mode). Find the LCOV and HTML report in the `coverage/lcov-report` folder.
That should be it! You should see messages from this plugin in the Cypress Command Log.
### More information
- Read [Cypress Code Coverage: Instrumenting code](https://on.cypress.io/code-coverage#Instrumenting-code) guide
- Watch [Code coverage](https://youtu.be/C8g5X4vCZJA) webinar
- Watch videos in [Cypress Tips & Tricks](https://www.youtube.com/playlist?list=PLP9o9QNnQuAYYRpJzDNWpeuOVTwxmIxcI) that deal with code coverage
### App vs unit tests
You need to instrument your web application. This means that when the test does `cy.visit('localhost:3000')` any code, the `index.html` requests should be instrumented by YOU. See the [Test Apps](#internal-test-apps) section for advice. Usually, you need to stick `babel-plugin-istanbul` into your pipeline somewhere.
If you are testing individual functions from your application code by importing them directly into Cypress spec files, this is called "unit tests" and Cypress can instrument this scenario for you. See [Instrument unit tests](#instrument-unit-tests) section.
## Reports
The `coverage` folder has results in several formats, and the coverage raw data is stored in the `.nyc_output` folder. You can see the coverage numbers yourself. This plugin has `nyc` as a dependency, so it should be available right away. Here are common examples:
```shell
# see just the coverage summary
$ npx nyc report --reporter=text-summary
# see just the coverage file by file
$ npx nyc report --reporter=text
# save the HTML report again
$ npx nyc report --reporter=lcov
```
It is helpful to enforce [minimum coverage](https://github.com/istanbuljs/nyc#common-configuration-options) numbers. For example:
```shell
$ npx nyc report --check-coverage --lines 80
----------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------|---------|----------|---------|---------|-------------------
All files | 100 | 100 | 100 | 100 |
main.js | 100 | 100 | 100 | 100 |
----------|---------|----------|---------|---------|-------------------
$ npx nyc report --check-coverage --lines 101
----------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------|---------|----------|---------|---------|-------------------
All files | 100 | 100 | 100 | 100 |
main.js | 100 | 100 | 100 | 100 |
----------|---------|----------|---------|---------|-------------------
ERROR: Coverage for lines (100%) does not meet global threshold (101%)
```
Watch the video [How to read code coverage report](https://youtu.be/yVvCYtsmkZU) to see how to read the HTML coverage report.
## Instrument unit tests
If you test your application code directly from `specs`, you might want to instrument them and combine unit test code coverage with any end-to-end code coverage (from iframe). You can easily instrument spec files using [babel-plugin-istanbul](https://github.com/istanbuljs/babel-plugin-istanbul), for example.
Install the plugin
```shell
npm i -D babel-plugin-istanbul
```
Set your `.babelrc` file.
```json
{
"plugins": ["istanbul"]
}
```
Put the following in the `cypress/plugins/index.js` file to use the `.babelrc` file.
```js
module.exports = (on, config) => {
require('@cypress/code-coverage/task')(on, config)
on('file:preprocessor', require('@cypress/code-coverage/use-babelrc'))
return config
}
```
The code coverage from spec files will be combined with end-to-end coverage.
Find examples of just the unit tests and JavaScript source files with collected code coverage in [test-apps/unit-tests-js](./test-apps/unit-tests-js).
### Alternative for unit tests
If you cannot use `.babelrc` (maybe it is used by other tools?), try using the Browserify transformer included with this module in the `use-browserify-istanbul` file.
```js
module.exports = (on, config) => {
require('@cypress/code-coverage/task')(on, config)
on(
'file:preprocessor',
require('@cypress/code-coverage/use-browserify-istanbul')
)
return config
}
```
## Instrument backend code
Example in [test-apps/backend](test-apps/backend) folder.
You can also instrument your server-side code and produce a combined coverage report that covers both the backend and frontend code.
1. Run the server code with instrumentation. The simplest way is to use [nyc](https://github.com/istanbuljs/nyc). If normally you run `node src/server`, then to run the instrumented version, you can do `nyc --silent node src/server`.
2. Add an endpoint that returns collected coverage. If you are using Express, you can do
```js
const express = require('express')
const app = express()
require('@cypress/code-coverage/middleware/express')(app)
```
**Tip:** You can register the endpoint only if there is a global code coverage object, and you can exclude the middleware code from the coverage numbers
```js
// https://github.com/gotwarlost/istanbul/blob/master/ignoring-code-for-coverage.md
/* istanbul ignore next */
if (global.__coverage__) {
require('@cypress/code-coverage/middleware/express')(app)
}
```
If you use a Hapi server, define the endpoint yourself and return the object.
```js
if (global.__coverage__) {
require('@cypress/code-coverage/middleware/hapi')(server)
}
```
For any other server, define the endpoint yourself and return the coverage object:
```js
if (global.__coverage__) {
// add method "GET /__coverage__" and response with JSON
onRequest = (response) => response.sendJSON({ coverage: global.__coverage__ })
}
```
3. Save the API coverage endpoint in the `cypress.json` file to let the plugin know where to call to receive the code coverage data from the server. Place it in `env.codeCoverage` object:
```json
{
"env": {
"codeCoverage": {
"url": "http://localhost:3000/__coverage__"
}
}
}
```
That should be enough - the code coverage from the server will be requested at the end of the test run and merged with the client-side code coverage, producing a combined report.
### expectBackendCoverageOnly
If there is NO frontend code coverage, and you only want to collect backend code coverage using Cypress tests, set `expectBackendCoverageOnly: true` in the `cypress.json` file. Otherwise, Cypress complains that it cannot find the frontend code coverage.
Default:
After:
```json
{
"env": {
"codeCoverage": {
"url": "http://localhost:3003/__coverage__",
"expectBackendCoverageOnly": true
}
}
}
```
## Custom report folder
You can specify a custom report folder by adding `nyc` object to the `package.json` file. For example, to save reports to `cypress-coverage` folder, use:
```json
{
"nyc": {
"report-dir": "cypress-coverage"
}
}
```
## Custom reporters
You can specify custom coverage reporter(s) to use. For example, to output text summary and save JSON report in the `cypress-coverage` folder set in your `package.json` folder:
```json
{
"nyc": {
"report-dir": "cypress-coverage",
"reporter": ["text", "json"]
}
}
```
**Tip:** find list of reporters [here](https://istanbul.js.org/docs/advanced/alternative-reporters/)
## Custom NYC command
Sometimes, the NYC tool might be installed in a different folder, not the current or parent folder, or you might want to customize the report command. In that case, put the custom command into `package.json` in the current folder, and this plugin will automatically use it.
```json
{
"scripts": {
"coverage:report": "call NYC report ..."
}
}
```
## TypeScript users
TypeScript source files should be automatically included in the report if they are instrumented.
See [test-apps/ts-example](test-apps/ts-example), [bahmutov/cra-ts-code-coverage-example](https://github.com/bahmutov/cra-ts-code-coverage-example) or [bahmutov/cypress-angular-coverage-example](https://github.com/bahmutov/cypress-angular-coverage-example).
## Include code
By default, the code coverage report includes _only_ the instrumented files loaded by the application during the tests. If some modules are loaded dynamically or by the pages NOT visited during any tests, these files will not be in the report - because the plugin does not know about them. You can include all expected source files in the report using the `include` list in the `package.json` file. The files without counters will have 0 percent code coverage.
For example, to ensure the final report includes all JS files from the "src/pages" folder, set the "nyc" object in your `package.json` file.
```json
{
"nyc": {
"all": true,
"include": "src/pages/*.js"
}
}
```
See example [test-app/all-files](./test-apps/all-files)
## Exclude code
You can exclude parts of the code or entire files from the code coverage report. See [Istanbul guide](https://github.com/gotwarlost/istanbul/blob/master/ignoring-code-for-coverage.md). Common cases:
### Exclude the "else" branch
The "else" branch will never be hit when running code only during Cypress tests. Thus, we should exclude it from the branch coverage computation:
```js
// expose "store" reference during tests
/* istanbul ignore else */
if (window.Cypress) {
window.store = store
}
```
### Exclude the next logical statement
Often needed to skip a statement.
```js
/* istanbul ignore next */
if (global.__coverage__) {
require('@cypress/code-coverage/middleware/express')(app)
}
```
Or a particular `switch` case
```js
switch (foo) {
case 1 /* some code */:
break
/* istanbul ignore next */
case 2: // really difficult to hit from tests
someCode()
}
```
### Exclude files and folders
The code coverage plugin will automatically exclude any test/spec files you have defined in the `testFiles` (Cypress < v10) or `specPattern` (Cypress >= v10) configuration options. Additionally, you can set the `exclude` pattern glob in the code coverage environment variable to specify additional files to be excluded:
```javascript
// cypress.config.js or cypress.json
env: {
codeCoverage: {
exclude: ['cypress/**/*.*'],
},
},
```
Cypress 10 and later users should set the `exclude` option to exclude any items from the `cypress` folder they don't want included in the coverage reports.
Additionally, you can use [`nyc` configuration](https://github.com/istanbuljs/nyc#common-configuration-options) and [include and exclude options](https://github.com/istanbuljs/nyc#using-include-and-exclude-arrays). You can include and exclude files using `minimatch` patterns in the `.nycrc` file or the "nyc" object inside your `package.json` file.
For example, if you want only to include files in the `app` folder but exclude the `app/util.js` file, you can set it in your `package.json`.
```json
{
"nyc": {
"include": ["app/**/*.js"],
"exclude": ["app/util.js"]
}
}
```
**Note:** If you have the `all: true` NYC option set, this plugin will check the produced `.nyc_output/out.json` before generating the final report. If the `out.json` file does not have information for some files that should be there according to the `include` list, then an empty placeholder will be included. See [PR 208](https://github.com/cypress-io/code-coverage/pull/208).
Another important option is `excludeAfterRemap`. By default, it is false, which might let excluded files through. If you exclude the files, and the instrumenter does not respect the `nyc.exclude` setting, then add `excludeAfterRemap: true` to tell `nyc report` to exclude files. See [test-apps/exclude-files](test-apps/exclude-files).
## Disable plugin
You can skip the client-side code coverage hooks by setting the environment variable `coverage` to `false`.
```shell
# tell Cypress to set environment variable "coverage" to false
cypress run --env coverage=false
# or pass the environment variable
CYPRESS_COVERAGE=false cypress run
```
Or set it to `false` in the `cypress.json` file.
```json
{
"env": {
"coverage": false
}
}
```
See [Cypress environment variables](https://on.cypress.io/environment-variables) and [support.js](support.js). You can try running without code coverage in this project yourself
```shell
# run with code coverage
npm run dev
# disable code coverage
npm run dev:no:coverage
```
## Links
- Read the [Cypress code coverage guide](http://on.cypress.io/code-coverage)
- Read ["Code Coverage by Parcel Bundler"](https://glebbahmutov.com/blog/code-coverage-by-parcel/) blog post
- Read ["Combined End-to-end and Unit Test Coverage"](https://glebbahmutov.com/blog/combined-end-to-end-and-unit-test-coverage/)
- If you are using React, check out [@cypress/instrument-cra](https://github.com/cypress-io/instrument-cra)
- Watch videos in [Cypress Tips & Tricks](https://www.youtube.com/playlist?list=PLP9o9QNnQuAYYRpJzDNWpeuOVTwxmIxcI) playlist
## Examples
### Internal test apps
Full examples we use for testing in this repository:
- [test-apps/backend](test-apps/backend) only instruments the backend Node server and saves the coverage report
- [test-apps/fullstack](test-apps/fullstack) instruments and merges backend, e2e and unit test coverage into a single report
- [test-apps/before-all-visit](test-apps/before-all-visit) checks if code coverage works when `cy.visit` is made once in the `before` hook
- [test-apps/before-each-visit](test-apps/before-each-visit) checks if code coverage correctly keeps track of code when doing `cy.visit` before each test
- [test-apps/one-spec](test-apps/one-spec) confirms that coverage is collected and filtered correctly if the user only executes a single Cypress test
- [test-apps/ts-example](test-apps/ts-example) uses Babel + Parcel to instrument and serve TypeScript file
- [test-apps/use-webpack](test-apps/use-webpack) shows Webpack build with source maps and Babel
- [test-apps/unit-tests-js](test-apps/unit-tests-js) runs just the unit tests and reports code coverage (JavaScript source code)
- [test-apps/unit-tests-ts](test-apps/ts-example) runs just the unit tests and reports code coverage (TypeScript source code)
### External examples
Look up the list of examples under the GitHub topic [cypress-code-coverage-example](https://github.com/topics/cypress-code-coverage-example)
- [cypress-io/cypress-realworld-app](https://github.com/cypress-io/cypress-realworld-app) is an easy to set up and run a real-world application with E2E, API, and unit tests that achieves 100% code-coverage for both front and back end code. Its CI pipeline also reports code-coverage reports across parallelized test runs to [Codecov](https://codecov.io/gh/cypress-io/cypress-realworld-app).
- [cypress-io/cypress-example-todomvc-redux](https://github.com/cypress-io/cypress-example-todomvc-redux) is a React / Redux application with 100% code coverage.
- [cypress-io/cypress-example-conduit-app](https://github.com/cypress-io/cypress-example-conduit-app) shows how to collect the coverage information from both back and frontend code and merge it into a single report. The E2E test step runs parallel in several CI containers, each saving just partial test coverage information. Then, a merge job runs, taking artifacts and combining coverage into the final report to be sent to an external coverage as a service app.
- [bahmutov/code-coverage-webpack-dev-server](https://github.com/bahmutov/code-coverage-webpack-dev-server) shows how to collect code coverage from an application that uses webpack-dev-server.
- [bahmutov/code-coverage-vue-example](https://github.com/bahmutov/code-coverage-vue-example) collects code coverage for Vue.js single file components.
- [lluia/cypress-typescript-coverage-example](https://github.com/lluia/cypress-typescript-coverage-example) shows coverage for React App that uses TypeScript. See discussion in issue [#19](https://github.com/cypress-io/code-coverage/issues/19).
- [bahmutov/cypress-and-jest](https://github.com/bahmutov/cypress-and-jest) shows how to run Jest unit tests and Cypress unit tests, collecting code coverage from both test runners and then producing a merged report.
- [bahmutov/cypress-angular-coverage-example](https://github.com/bahmutov/cypress-angular-coverage-example) forked from [skylock/cypress-angular-coverage-example](https://github.com/skylock/cypress-angular-coverage-example) shows Angular 8 + TypeScript application with instrumentation done using [istanbul-instrumenter-loader](https://github.com/webpack-contrib/istanbul-instrumenter-loader).
- [bahmutov/testing-react](https://github.com/bahmutov/testing-react) shows how to get code coverage for a React application created using [CRA v3](https://github.com/facebook/create-react-app) without ejecting `react-scripts`.
- [bahmutov/cra-ts-code-coverage-example](https://github.com/bahmutov/cra-ts-code-coverage-example) instruments TypeScript React application on the fly without ejecting `react-scripts` by using [@cypress/instrument-cra](https://github.com/cypress-io/instrument-cra).
- [bahmutov/next-and-cypress-example](https://github.com/bahmutov/next-and-cypress-example) shows how to get backend and frontend coverage for a [Next.js](https://nextjs.org) project. Uses [middleware/nextjs.js](middleware/nextjs.js).
- [kylemh/next-ts-with-cypress-coverage](https://github.com/kylemh/next-ts-with-cypress-coverage) This example project contains Next.js with TypeScript, instrumented coverage reporting, @testing-library/react, and instructions on how to type custom commands.
- [akoidan/vue-webpack-typescript](https://github.com/akoidan/vue-webpack-typescript) Pure webpack config with vue + typescript with codecov reports. This setup uses a babel-loader with a TS checker as a separate thread.
- [bahmutov/code-coverage-subfolder-example](https://github.com/bahmutov/code-coverage-subfolder-example) shows how to instrument the `app` folder using `nyc instrument` as a separate step before running E2E tests
- [bahmutov/docker-with-cypress-included-code-coverage-example](https://github.com/bahmutov/docker-with-cypress-included-code-coverage-example) runs tests inside pre-installed Cypress using [cypress/included:x.y.z](https://github.com/cypress-io/cypress-docker-images/tree/master/included) Docker image and reports code coverage.
- [bahmutov/app-in-docker-coverage-example](https://github.com/bahmutov/app-in-docker-coverage-example) shows an app running inside a Docker container, while Cypress runs on the local machine. Before generating the report, Cypress can still [discover the source files](https://github.com/cypress-io/code-coverage/pull/197).
- [bahmutov/gatsby-cypress-with-code-coverage](https://github.com/bahmutov/gatsby-cypress-with-code-coverage) shows code coverage using the official Gatsby "Hello World" starter.
- [muratkeremozcan/angular-playground](https://github.com/muratkeremozcan/angular-playground) is an Angular TypeScript application with combined unit and E2E coverage.
- [nefayran/cypress-react-vite](https://github.com/nefayran/cypress-react-vite) React with Vite and Istanbul plugin for code coverage.
## Migrations
### Cypress v9 to v10
With the removal of the `plugins` directory in Cypress version 10+, you'll need to add all of your configuration into the configuration file (`cypress.config.js` by default).
```js
// BEFORE
// Register tasks in your `cypress/plugins/index.js` file.
module.exports = (on, config) => {
require('@cypress/code-coverage/task')(on, config)
// add other tasks to be registered here
// IMPORTANT to return the config object
// with the any changed environment variables
return config
}
```
```js
// AFTER
// cypress.config.js
const { defineConfig } = require('cypress')
module.exports = defineConfig({
// setupNodeEvents can be defined in either
// the e2e or component configuration
e2e: {
setupNodeEvents(on, config) {
require('@cypress/code-coverage/task')(on, config)
// include any other plugin code...
// It's IMPORTANT to return the config object
// with any changed environment variables
return config
},
},
})
```
### v2 to v3
Change the plugins file `cypress/plugins/index.js`
```js
// BEFORE
module.exports = (on, config) => {
on('task', require('@cypress/code-coverage/task'))
}
// AFTER
module.exports = (on, config) => {
require('@cypress/code-coverage/task')(on, config)
// IMPORTANT to return the config object
// with the any changed environment variables
return config
}
```
**Tip:** We include [plugins.js](plugins.js) file you can point at from your code in simple cases. From your `cypress.json` file:
```json
{
"pluginsFile": "node_modules/@cypress/code-coverage/plugins",
"supportFile": "node_modules/@cypress/code-coverage/support"
}
```
## Debugging
This plugin uses the [debug](https://github.com/visionmedia/debug) module to output additional logging messages from its [task.js](task.js) file. This can help with debugging errors while saving code coverage or reporting. To see these messages, run Cypress from the terminal with the environment variable `DEBUG=code-coverage`. Example using Unix syntax to set the variable:
```shell
$ DEBUG=code-coverage npm run dev
...
code-coverage reset code coverage in interactive mode +0ms
code-coverage wrote coverage file /code-coverage/.nyc_output/out.json +28ms
code-coverage saving coverage report using the command: "nyc report --report-dir ./coverage --reporter=lcov --reporter=clover --reporter=json" +3ms
```
Deeply nested objects will sometimes have `[object Object]` values printed. You can print these nested objects by specifying a deeper depth by adding `DEBUG_DEPTH=` setting.
```shell
DEBUG_DEPTH=10 DEBUG=code-coverage npm run dev
```
### Common issues
Common issue: [not instrumenting your application when running Cypress](#instrument-your-application).
If the plugin worked before in version X but stopped after upgrading to version Y, please try the [released versions](https://github.com/cypress-io/code-coverage/releases) between X and Y to see where the breaking change was.
If you decide to open an issue in this repository, please fill in all information the [issue template](https://github.com/cypress-io/code-coverage/blob/master/.github/ISSUE_TEMPLATE/bug_report.md) asks for. The issues most likely to be resolved have debug logs, screenshots, and hopefully public repository links so we can try running the tests ourselves.
## Contributing
You can test changes locally by running tests and confirming that the code coverage has been calculated and saved.
```shell
npm run test:ci
# now check generated coverage numbers
npx nyc report --check-coverage true --lines 80
npx nyc report --check-coverage true --lines 100 --include cypress/about.js
npx nyc report --check-coverage true --lines 100 --include cypress/unit.js
```
**Tip:** use [check-code-coverage](https://github.com/bahmutov/check-code-coverage) for stricter code coverage checks than `nyc report --check-coverage` allows.
### Markdown
You can validate links in Markdown files in this directory by executing (Linux + Mac only) script.
```shell
npm run check:markdown
```
## License
This project is licensed under the terms of the [MIT license](LICENSE.md).
[renovate-badge]: https://img.shields.io/badge/renovate-app-blue.svg
[renovate-app]: https://renovateapp.com/