refactor: use TestContainers

Author: m4tx

CONTRIBUTING.md

@@ -46,18 +46,11 @@ instructions. This handles formatting of all the files in the repository.
 ### Tests that use database, cache, or other external resources
 
 Some tests use a database, cache, or other external resources. All these tests
-are marked with `#[ignore]`, so they are not run by default.
+are marked with `#[ignore]`, but they will automatically start the necessary
+containers using [Testcontainers](https://testcontainers.org/) if you have
+Docker or a similar container runtime installed.
 
-If you want to run the full test suite, it's necessary to run these external
-dependencies. For convenience, Cot provides a
-[Docker compose file](./compose.yml) in the root of the repository that
-contains all the dependencies needed to run the tests. You can run it with:
-
-```sh
-docker compose up -d
-```
-
-Then, the tests can be run with:
+If you want to run the full test suite, you can run:
 
 ```sh
 cargo test --all-features --include-ignored
@@ -66,17 +59,11 @@ cargo test --all-features --include-ignored
 #### End-to-end tests
 
 End-to-end tests require a running webdriver server. By default, a Selenium
-Grid server is used (included in the `compose.yml` file). You can access the
-UI to see the tests running (for example, to debug them) at
-`http://localhost:7900/?autoconnect=1&resize=scale&password=secret`.
-
-Alternatively, instead of using Selenium Grid, you can run the tests with
-a local webdriver server. To do this, you need to install and run the
-Webdriver implementation of your choice, such as
-[geckodriver](https://github.com/mozilla/geckodriver/releases) or
-[chromedriver](https://developer.chrome.com/docs/chromedriver/downloads).
-After running the webdriver server, you will see the tests running in a
-local browser window.
+container is automatically started using Testcontainers.
+
+Alternatively, you can run the tests with a local webdriver server. To do this,
+you need to set the `WEBDRIVER_URL` environment variable to the URL of your
+local webdriver server (e.g., `http://localhost:4444`).
 
 ### Snapshot tests