# End-to-end tests with Cypress

Metabase uses Cypress for “end-to-end testing”, that is, tests that are executed against the application as a whole, including the frontend, backend, and application database. These tests are essentially scripts written in JavaScript that run in the web browser: visit different URLs, click various UI elements, type text, and assert that things happen as expected (for example, an element appearing on screen, or a network request occurring).

_Please, get familiar with the [Cypress best practices](https://docs.cypress.io/app/core-concepts/best-practices) before you proceed._

## Getting Started

Metabase’s Cypress tests are located in the `e2e/test/scenarios` source tree, in a structure that roughly mirrors Metabase’s URL structure. For example, tests for the admin “datamodel” pages are located in `e2e/test/scenarios/admin/datamodel`.

Our custom Cypress runner builds its own backend and creates a temporary H2 app db. Both are destroyed when this process is killed. The reserved default port is `4000` on the local host. There is nothing stopping you from running your local Metabase instance on `localhost:3000` at the same time. This might even be helpful for debugging purposes.

### Standard Development Flow

1. Continuously build the frontend

a. If you need only the frontend, run `bun run build-hot`

b. If you want to run a local Metabase instance alongside Cypress, the easiest way to achieve this is by using `bun run dev` or `bun run dev-ee` (both rely on frontend hot reloading under the hood)

2. In a separate terminal session (without killing the previous one) run `bun run test-cypress`. This will open a Cypress GUI that will let you choose which tests to run. Alternatively, take a look at `run_cypress_local.js` and `e2e/test/scenarios/docker-compose.yml` for all possible options.

### Running Options

To run all Cypress tests headlessly in the terminal:

```
CYPRESS_GUI=false bun run test-cypress
```

You can quickly test a single file only by using the official `--spec` flag. This flag can be used to run all specs within a folder, or to run multiple assorted specs. Consult [the official documentation](https://docs.cypress.io/app/references/command-line#cypress-run-spec-lt-spec-gt) for instructions.

```
CYPRESS_GUI=false bun run test-cypress --spec e2e/test/scenarios/question/new.cy.spec.js
```

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