The server is the heart of the Cypress application. All of this code represents the node process running behind the browser application. This node process is responsible for:

Proxying every byte coming in and out of the browser
Performing and normalizing automation tasks for each browser
Coordinating and synchronizing state with the launchpad and driver packages
Performing node specific tasks on behalf of the driver
Instantiating and orchestrating nearly every other layer and package
Spinning up various static file and http servers
Communicating with our external API's
Recording videos of run
Managing mocha reporters
Managing 3rd party plugins

The driver and the server are the two most complex packages of Cypress.

Developing

To run the Cypress server:

## boots the entire Cypress application
yarn start

Since the server controls nearly every aspect of Cypress, after making changes you'll need to manually restart Cypress.

Since this is slow, it's better to drive your development with tests.

Building

Note: you should not ever need to build the .js files manually. @packages/ts provides require-time transpilation when in development.

yarn workspace @packages/server build-prod

yarn test-unit executes unit tests in test/unit
yarn test-integration executes integration tests in test/integration
yarn test-performance executes performance tests in test/performance

You can also use the test-watch command to rerun a test file whenever there is a change:

yarn test-watch /test/path/to/spec.js

Running individual unit tests

yarn test <path/to/test>
yarn test test/unit/api_spec.js
## or
yarn test-unit api_spec ## shorthand, uses globbing to find spec

Running individual integration tests

yarn test <path/to/test>
yarn test test/integration/cli_spec.js
## or
yarn test-integration cli_spec ## shorthand, uses globbing to find spec

Running e2e/system tests

With the addition of Component Testing, e2e tests have been renamed to system-tests and moved to the system-tests directory.

Updating snapshots

Prepend SNAPSHOT_UPDATE=1 to any test command. See snap-shot-it instructions for more info.

SNAPSHOT_UPDATE=1 yarn test test/unit/api_spec.js
SNAPSHOT_UPDATE=1 yarn test test/integration/cli_spec.js

V8 Snapshots

In order to improve start up time, Cypress uses electron mksnapshot for generating v8 snapshots for both development and production.

Cypress code is automatically set up to run using snapshots. If you want to run Cypress in development without the v8 snapshot (for debugging purposes or to see if there's a problem with the snapshot or the code itself) you can set the environment variable DISABLE_SNAPSHOT_REQUIRE to 1 or true.