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Contributing to Cypress

Thanks for taking the time to contribute! 😄

Once you learn how to use Cypress, you can contribute in many ways:

Want to dive deeper into how Cypress works? There are several ways you can help with the development of Cypress:

Table of Contents

Code of Conduct

All contributors are expecting to abide by our Code of Conduct.

Opening Issues

The most important things to do are:

Finally, if you are up to date, supported, have collected information about the problem, and have the best reproduction instructions you can give, you are ready to open an issue.

Update Cypress

Before filing a bug, make sure you are up to date. Your issue may have already been fixed. Even if you do not see the issue described as resolved in a newer version, a newer version may help in the process of debugging your issue by giving more helpful error messages.

See our document on installing cypress

Getting more information

For some issues, there are places you can check for more information. This may help you resolve the issue yourself. Even if it doesn't, this information can help us figure out and resolve an issue.

  • For issues in the web browser, check the JavaScript console and your Network tab in your DevTools.
  • Click on any command in the Command Log where the failure occurred, this will log more information about the error to the JavaScript console.
  • Use Cypress debug or pause commands to step through your commands.
  • Ask other Cypress users for help in our chat or Discord.
  • Try more advanced troubleshooting from troubleshooting Cypress doc.

Fill out our Issue Template

When opening an issue, there is a provided issue template. Fill out the information according to the template. This is information needed for Cypress to continue forward with your problem. Any issues that don't fill out the issue template will be closed.

Describe Problems

When you file a feature request or bug, it's best to describe the problem you are facing first, not just your desired solution.

Often, your problem may have a lot in common with other similar problems. If we understand your use case, we can compare it to other use cases and sometimes find a more powerful or more general solution which solves several problems at once. Understanding the root issue can let us merge and contextualize things. Sometimes there's already a way to solve your problem that might just not be obvious.

Also, your proposed solution may not be compatible with the direction we want to take the product, but we may be able to come up with another solution which has approximately the same effect and does fit into the product direction.

Reproducibility

It is nearly impossible for us to resolve issues if we can not reproduce them. Your best chance of getting a bug looked at quickly is to provide a repository with a reproducible bug that can be cloned and run.

Common issues

Label Description Issues
browser detection Local browser is not detected open, closed
cross-origin Getting cross-origin error open, closed
cy.request Issues related to cy.request command open, closed
fixtures Fixture loading and usage
hooks Issues related to hooks open, closed
iframes Working with iframes open, closed
installation Cypress cannot be downloaded or installed open, closed
network Controlling network requests open, closed
performance Slow loading, slow network, etc open, closed
screenshots Taking image screenshots open, closed
scrolling Scrolling elements into view open, closed
spec execution Running all specs or some specs in some specific order open
test execution Running tests inside a single spec open, closed
typescript Transpiling or bundling TypeScript open, closed
video Problems with video recordings open, closed

Writing Documentation

Cypress documentation lives in a separate repository with its own dependencies and build tools. See Documentation Contributing Guideline.

Writing code

Working on your first Pull Request? You can learn how from this free series How to Contribute to an Open Source Project on GitHub

What you need to know before getting started

Cypress and Packages

Cypress is a large open source project. When you want to contribute to Cypress, you may be unsure which part of the project to work within.

Cypress uses a monorepo, which means there are many independent packages in this repository. There are two main types of packages: private and public.

Private packages generally live within the packages directory and are in the @packages/ namespace. These packages are combined to form the main Cypress app that you get when you npm install cypress. They are discrete modules with different responsibilities, but each is necessary for the Cypress app and is not necessarily useful outside of the Cypress app. Since these modules are all compiled and bundled into a binary upon release, they are sometimes collectively referred to as the Cypress binary.

Here is a list of the core packages in this repository with a short description, located within the packages directory:

Folder Name Package Name Purpose
cli cypress The command-line tool that is packaged as an npm module.
app @packages/app The the front-end for the Cypress App that renders in the launched browser instance.
config @packages/config The Cypress configuration types and validation used in the server, data-context and driver.
data-context @packages/data-context Centralized data access for the Cypress application.
driver @packages/driver The code that is used to drive the behavior of the API commands.
electron @packages/electron The Cypress implementation of Electron.
example @packages/example Our example kitchen-sink application.
extension @packages/extension The Cypress Chrome browser extension
frontend-shared @packages/frontend-shared Shared components and styles used in the app and launchpad.
graphql @packages/graphql The GraphQL layer that the launchpad and app use to interact with the server.
https-proxy @packages/https-proxy This does https proxy for handling http certs and traffic.
icons @packages/icons The Cypress icons.
launcher @packages/launcher Finds and launches browsers installed on your system.
launchpad @packages/launcher The portal to running Cypress that displays in open mode.
net-stubbing @packages/net-stubbing Contains server side code for Cypress' network stubbing features.
network @packages/network Various utilities related to networking.
proxy @packages/proxy Code for Cypress' network proxy layer.
reporter @packages/reporter The reporter shows the running results of the tests (The Command Log UI).
resolve-dist @packages/resolve-dist Centralizes the resolution of paths to compiled/static assets from server-side code..
rewriter @packages/rewriter The logic to rewrite JS and HTML that flows through the Cypress proxy.
root @packages/root Dummy package pointing at the root of the repository.
runner @packages/runner (deprecated) The runner is the minimal "chrome" around the user's application under test.
scaffold-config @packages/scaffold-config The logic related to scaffolding new projects using launchpad.
server @packages/server The <3 of Cypress. This orchestrates everything. The backend node process.
socket @packages/socket A wrapper around socket.io to provide common libraries.
ts @packages/ts A centralized version of typescript.
types @packages/types The shared internal Cypress types.
web-config @packages/ui-components The web-related configuration.

Public packages live within the npm folder and are standalone modules that get independently published to npm under the @cypress/ namespace. These packages generally contain extensions, plugins, or other packages that are complementary to, yet independent of, the main Cypress app.

Here is a list of the npm packages in this repository:

Folder Name Package Name Purpose
angular @cypress/angular Cypress component testing for Angular.
create-cypress-tests @cypress/create-cypress-tests Tooling to scaffold Cypress configuration and demo test files.
eslint-plugin-dev @cypress/eslint-plugin-dev Eslint plugin for internal development.
grep @cypress/grep Filter tests using substring
mount-utils @cypress/mount-utils Common functionality for Vue/React/Angular adapters.
react @cypress/react Cypress component testing for React.
react18 @cypress/react18 Cypress component testing for React 18.
schematic @cypress/schematic Official Angular Schematic and Builder for the Angular CLI.
svelte @cypress/svelte Cypress component testing for Svelte.
vite-dev-server @cypress/vite-dev-server Vite powered dev server for Component Testing.
vue @cypress/vue Cypress component testing for Vue 3.
vue2 @cypress/vue2 Cypress component testing for Vue 2.
webpack-batteries-included-preprocessor @cypress/webpack-batteries-included-preprocessor Cypress preprocessor for bundling JavaScript via webpack with dependencies included and support for various ES features, TypeScript, and CoffeeScript.
webpack-dev-server @cypress/webpack-dev-server Webpack powered dev server for Component Testing.
webpack-preprocessor @cypress/webpack-preprocessor Cypress preprocessor for bundling JavaScript via webpack.
xpath @cypress/xpath Adds XPath command to Cypress.io test runner

We try to tag all issues with a pkg/ or npm/ tag describing the appropriate package the work is required in. For public packages, we use their qualified package name: For example, issues relating to the webpack preprocessor are tagged under npm: @cypress/webpack-preprocessor label and issues related to the driver package are tagged with the pkg/driver label.

Requirements

You must have the following installed on your system to contribute locally:

  • Node.js (See the root .node-version file for minimum version requirements. You can use avn to automatically switch to the right version of Node.js for this repo.)
  • yarn
  • python (since we use node-gyp. See their repo for Python version requirements.)

Getting Started

The project utilizes yarn workspaces and leverages lerna to orchestrate running within the context of one or more packages. While it is not as important to understand lerna or yarn workspaces, it is important to note that running scripts or installing new dependencies should always happen from the repo's root directory.

⚠ Running on Windows?

If you are running a Windows operating system, you may encounter some commands that are not working. In order to resolve paths correctly during the development build process, you may need to explicitly set your default yarn shell script to Command Prompt by using the following command:

yarn config set script-shell "C:\\Windows\\system32\\cmd.exe"

Install all dependencies:

yarn

This will install all the dependencies for the repo and perform a preliminary build.

Next, start the app:

yarn start

If there are errors building the packages, prefix the commands with DEBUG=cypress:* to see more details. This outputs a lot of debugging lines. To focus on an individual module, run with DEBUG=cypress:launcher:* for instance. See "Debug logs" for more info.

When running yarn start this routes through the CLI and eventually calls yarn dev with the proper arguments. This enables Cypress day-to-day development to match the logic of the built binary + CLI integration.

If you want to bypass the CLI entirely, you can use the yarn dev task and pass arguments directly. For example, to headlessly run a project in a given folder, while trying to record to the Dashboard

yarn dev --run-project /project/folder --record --key <key>

Adding new Dependencies

⚠️ There is a bug in yarn that may cause issues adding a new dependency to a workspace. You can avoid this by downgrading yarn to 1.19.1 (temporarily downgrade using npx [email protected] workspace @packages/server add my-new-dep1).

# add a new dep to the root of the repo
$ yarn add -W my-new-dep1

# add a new dep to a specific package
$ yarn workspace @packages/server add my-new-dep1
$ yarn workspace @packages/server add --dev my-new-dep1

Alternatively, you can directly add the dependency to the corresponding package.json and run yarn.

Tasks

Scripts are intended to be run from the root of the repo. Do not install dependencies or run scripts from within a sub-directory.

Common Top Level Tasks

By default, top level tasks will execute for all packages. However, most scripts can be provided one or more scopes. Providing a scope will execute tasks within the provided packages. Scope values are based on package names and not the directory structure.

Task Purpose
build Compile non-node code (typescript)
start Open Cypress in dev and global mode
watch Auto-rebuild on file changes
clean Remove build artifacts
clean-deps Remove all installed dependencies (in root and in every package)
test Run the default set of tests (may be package dependent)
test-debug Run unit/integration tests with inspect node CLI flags
test-unit Run unit tests
test-integration Run integration tests
test-e2e Run end-to-end tests
test-system Run system tests
test-watch Run unit tests and rebuild/rerun on file changes

Most of the time you will only want to run a task within a specific package; this can be done by providing the package name as a scope to the top level task.

# Run test-unit only within cypress package (./cli)
$ yarn test-unit --scope cypress

# Run test-unit only within the cypress and server packages (./cli & ./packages/server)
$ yarn test-unit --scope cypress --scope @packages/server

# Run test-unit in all packages with the name starting with `@packages/`
$ yarn test-unit --scope @packages/*
Package-Level Scripts

Although scripts are meant to be run from the root of the repo; they typically delegate to the scripts within the packages.

Each package is responsible for building itself and testing itself and can do so using whatever tools are appropriate, but each conforms to a standard set of scripts so that building, watching, testing, etc. can be orchestrated from the root of this repo. Here are the scripts supported and what they mean:

Task Purpose
build Build the package
build-prod Build all assets for production (if makes sense)
start Run a server for serving files
watch Watch source files and build development assets when they are saved. This may also run a server for serving files and run tests related to a saved file.
clean Remove any assets created by build-dev or build-prod
clean-deps Remove any dependencies installed (usually by yarn)
test Runs all tests once (this usually means running unit tests; via yarn test-unit)
test-unit Run all unit tests within the package; exit 0 if N/A
test-integration Run all integration tests within the package; exit 0 if N/A
test-watch Run all unit tests in the package in watch mode

Internal Vite Options

When executing top or package level scripts, Vite may be used to build/host parts of the application. This section is to serve as a general reference for these environment variables that may be leverage throughout the repository.

CYPRESS_INTERNAL_VITE_DEV

Set to 1 if wanting to leverage vite's vite dev over vite build to avoid a full production build.

CYPRESS_INTERNAL_VITE_INSPECT

Used internally to leverage vite-plugin-inspect to view intermediary vite plugin state. The CYPRESS_INTERNAL_VITE_DEV is required for this to be applied correctly. Set to 1 to enable.

CYPRESS_INTERNAL_VITE_OPEN_MODE_TESTING

Leveraged only for internal cy-in-cy type tests to access the Cypress instance from the parent frame. Please see the E2E Open Mode Testing Guide. Set to true when doing

CYPRESS_INTERNAL_VITE_APP_PORT

Leveraged only when CYPRESS_INTERNAL_VITE_DEV is set to spawn the vite dev server for the app on the specified port. The default port is 3333.

CYPRESS_INTERNAL_VITE_LAUNCHPAD_PORT

Leveraged only when CYPRESS_INTERNAL_VITE_DEV is set to spawn the vite dev server for the launchpad on the specified port. The default port is 3001.

Debug Logs

Many Cypress packages print out debugging information to console via the debug module. See "Debug logs" for more information.

Coding Style

We use eslint to lint all JavaScript code and follow rules specified in @cypress/eslint-plugin-dev plugin.

When you edit files, you can quickly fix all changed files before you commit using

$ yarn lint-changed --fix

When committing files, we run a Git pre-commit hook to lint the staged JS files. See the lint-staged project. If this command fails, you may need to run yarn lint-changed --fix and commit those changes.

We DO NOT use Prettier to format code. You can find .prettierignore file that ignores all files in this repository. To ensure this file is loaded, please always open the root repository folder in your text editor, otherwise your code formatter might execute, reformatting lots of source files.

Adding links within code

When adding links to outside resources within the Cypress Test Runner (including links to Cypress's own documentation), we utilize our cypress-on service for all links.

This is to ensure that links do not go dead in older versions of Cypress when the location of the link has changed. To add a new link:

  • Make up a new slug for the linked resource like https://on.cypress.io/my-special-link.
  • Open a PR adding the new slug in links.yml with the href of the resource it should redirect to. Note: this requires access to the internal cypress-services repo which is only granted to Cypress employees. If you're an outside contributor and need a link reroute added, please comment in the relevant PR asking for assistance.
  • Wait for the PR to be reviewed and deployed from cypress-services. This is required before your changes can be merged into the cypress project.

Tests

For most packages there are typically unit and integration tests.

Please refer to each packages' README.md which documents how to run tests. It is not feasible to try to run all of the tests together. We run our entire test fleet across over a dozen containers in CI.

There are also a set of system tests in system-tests which attempt to test the entire Cypress App as close to real world as possible. See the README for more information.

Additionally, we test the code by running it against various other example projects in CI. See CI badges and links at the top of this document.

If you're curious how we manage all of these tests in CI check out our CircleCI config.

Docker

Sometimes tests pass locally, but fail in CI. Our CI environment is dockerized. In order to run the image used in CI locally:

  1. Install Docker and get it running on your machine.
  2. Run the following command from the root of the project:
$ yarn docker

There is a script scripts/run-docker-local.sh that runs the cypress image (see CircleCI config for the current image name).

The image will start and will map the root of the repository to /cypress inside the image. Now you can modify the files using your favorite environment and rerun tests inside the docker environment.

Docker for built binary

You can also use Docker to simulate and debug the built binary. In a temporary folder (for example from the folder /tmp/test-folder/) start a Docker image:

$ docker run -it -w /app -v $PWD:/app cypress/base:8 /bin/bash

Point the installation at a specific beta binary and NPM package archive (if needed) and set local cache folder to unzip the downloaded binary into a subfolder.

$ export CYPRESS_INSTALL_BINARY=https://cdn.cypress.io/beta/.../cypress.zip
$ export CYPRESS_CACHE_FOLDER=./cypress-cache
$ yarn add https://cdn.cypress.io/beta/npm/.../cypress.tgz

Note that unzipping the Linux binary inside a Docker container onto a mapped volume drive is slow. But once this is done you can modify the application resource folder in the local folder /tmp/test-folder/node_modules/cypress/cypress-cache/3.3.0/Cypress/resources/app to debug issues.

Packages

Generally when making contributions, you are typically making them to a small number of packages. Most of your local development work will be inside a single package at a time.

Each package documents how to best work with it, so consult the README.md of each package.

They will outline development and test procedures. When in doubt just look at the scripts of each package.json file. Everything we do at Cypress is contained there.

Committing Code

Branches

The repository has one protected branch:

  • develop contains the current latest "pre-release" code for the Cypress app and contains the already published code of all standalone npm packages Cypress maintains. This branch is set as the default branch, and all pull requests should be made against this branch.

We want to publish our standalone npm packages continuously as new features are added. Therefore, after any pull request that changes independent @cypress/ packages in the npm directory will automatically publish when a PR is merged directly into develop and the entire build passes. We used semantic-release to automate the release of these packages to npm.

We do not continuously deploy the Cypress binary, so develop contains all of the new features and fixes that are staged to go out in the next update of the main Cypress app. If you make changes to an npm package that can't be published until the binary is also updated, you should make a pull request against specifying this is not be merged until the scheduled Cypress app release date.

Pull Requests

  • Break down pull requests into the smallest necessary parts to address the original issue or feature. This helps you get a timely review and helps the reviewer clearly understand which pieces of the code changes are relevant.
  • When opening a PR for a specific issue already open, please name the branch you are working on using the convention issue-[issue number]. For example, if your PR fixes Issue #803, name your branch issue-803. If the PR is a larger issue, you can add more context like issue-803-new-scrollable-area. If there's not an associated open issue, create an issue.
  • PRs can be opened before all the work is finished. In fact we encourage this! Please create a Draft Pull Request if your PR is not ready for review. Mark the PR as Ready for Review when you're ready for a Cypress team member to review the PR.
  • Prefix the title of the Pull Request using semantic-release's format as defined here. For example, if your PR is fixing a bug, you should prefix the PR title with fix:.
  • Fill out the Pull Request Template completely within the body of the PR. If you feel some areas are not relevant add N/A as opposed to deleting those sections. PR's will not be reviewed if this template is not filled in.
  • If the PR is a user facing change and you're a Cypress team member that has logged into ZenHub and downloaded the ZenHub for GitHub extension, set the release the PR is intended to ship in from the sidebar of the PR. Follow semantic versioning to select the intended release. This is used to generate the changelog for the release. If you don't tag a PR for release, it won't be mentioned in the changelog. Select release for PR
  • Please check the "Allow edits from maintainers" checkbox when submitting your PR. This will make it easier for the maintainers to make minor adjustments, to help with tests or any other changes we may need. Allow edits from maintainers checkbox
  • All Pull Requests require a minimum of two approvals.
  • After the PR is approved, the original contributor can merge the PR (if the original contributor has access).
  • When you merge a PR into develop, select Squash and merge. This will squash all commits into a single commit. The only exception to squashing is when converting files to another language and there is a clear commit history needed to maintain from the file conversion.

Write Some Tests

If you are adding a new feature or fixing a regression, ensure you add tests for it. Broadly speaking, there are three categories of tests you might consider:

  1. Unit test. Those are inside of test/unit, if the package has them. These are the fastest and cheapest to execute.
  2. E2E/Integration tests. Those are inside cypress/e2e, if the package has them. These are between Unit Tests and System Tests when it comes to speed of execution.
  3. System Tests. Those go in the system-tests directory. The README explains how they work. These are the slowest to run, so you generally only want to add a system-test if it's absolutely required (but don't let that discourage you; they are also the most realistic way to test Cypress).

When choosing what's most appropriate, consider:

  • ease of understanding
  • ease of debugging
  • resilience to refactoring

Dependencies

We use RenovateBot to automatically upgrade our dependencies. The bot uses the settings in renovate.json to maintain our Update Dependencies issue and open PRs. You can manually select a package to open a PR from our Update Dependencies issue.

After a PR has been opened for a dependency update, our cypress-bot will comment on the PR detailing the guidelines to be used to review the dependency update. Please read these guidelines carefully and make any updates where you see the PR may not be meeting the quality of these guidelines.

Reviewing Code

Some rules about Code Review

  1. The contributor opening the pull request may not approve their own PR.
  2. The PR will not be merged if some reviewers have requested changes.

If any of the Pull Request Review guidelines can't be met, a comment should be left by the reviewer with 'Request changes'. The original contributor is responsible for making any updates and request re-review once those changes are addressed.

Steps to take during Code Review

  • Run the code and use it as the end user would.
  • Double check the issue and PR description to ensure it is meeting the original requirements.
  • Read through every line of changed code (Yes, we know this could be a LOT).
  • If you don't understand why some piece of code is required, ask for clarification! Likely the contributor had a reason and can provide the answer quicker than investigating yourself.

Code Review Checklist

Below are guidelines to help during code review. If any of the following requirements can't be met, leave a comment in the review selecting 'Request changes', otherwise 'Approve'.

User Experience

  • The feature/bugfix is self-documenting from within the product.
  • The change provides the end user with a way to fix their problem (no dead ends).
  • If a breaking change or a change to a commonly used API, the proposed changes have been discussed and agreed upon in the weekly team meeting (or a separate meeting if a larger change).

Functionality

  • The code works and performs its intended function with the correct logic.
  • Performance has been factored in (for example, the code cleans up after itself to not cause memory leaks).
  • The code guards against edge cases and invalid input and has tests to cover it.

Maintainability

  • The code is readable (too many nested 'if's are a bad sign).
  • Names used for variables, methods, etc, clearly describe their function.
  • The code is easy to understand and there are relevant comments explaining.
  • New algorithms are documented in the code with link(s) to external docs (flowcharts, w3c, chrome, firefox).
  • There are comments containing link(s) to the addressed issue (in tests and code).

Quality

  • The change does not reimplement code.
  • There's not a module from the ecosystem that should be used instead.
  • There is no redundant or duplicate code.
  • There are no irrelevant comments left in the code.
  • There is no irrelevant code to the issue being addressed. If there is, ask the contributor to break the work out into a separate PR.
  • Tests are testing the code's intended functionality in the best way possible.

Internal

  • The original issue has been tagged with a release in ZenHub.

Code Review of Dependency Updates

Below are some guidelines Cypress uses when reviewing dependency updates.

Dependency Update Instructions

  • Read through the entire changelog of the dependency's changes. If a changelog is not available, check every commit made to the dependency. NOTE - do not rely on semver to indicate breaking changes - every product does not follow this standard.
  • Add a PR review comment noting any relevant changes in the dependency.
  • If any of the following requirements cannot be met, leave a comment in the review selecting 'Request changes', otherwise 'Approve'.

Dependency Updates Checklist

  • Code using the dependency has been updated to accommodate any breaking changes
  • The dependency still supports the version of Node that the package requires.
  • The PR been tagged with a release in ZenHub.
  • Appropriate labels have been added to the PR (for example: label type: breaking change if it is a breaking change)

Releases

Standalone npm packages are deployed immediately when a PR is merged into develop and the entire build passes.

The Cypress app is typically released every two weeks. All PRs merged to develop will build a "pre-released" Cypress app which can be installed to verify or leverage your changes before the scheduled release. Read these instructions for installing pre-release versions.

If you want to know our build process or build your own Cypress binary, read the "Release Process" guide.

Known problems

ENFILE or EMFILE

If you get ENFILE: file table overflow, ENFILE: too many open files or any other ENFILE or EMFILE errors on Mac, that means you are doing synchronous file system operations. Cypress should NEVER do them. Instead we should use async file system operations and let graceful-fs retry them. Find the place where the synchronous fs operation is done from the stacktrace and make it async.

lock file

You can rebuild the lock file using the latest develop version in a clean isolated environment using Docker. From the current branch:

git checkout develop
git pull
git checkout -
git checkout origin/develop -- yarn.lock
# remove all unknown files
git clean -xfd
yarn