A dive into integration and end-to-end testing in Go.
Presentation at Poznań Go Devs #9
app_to_test contains very simple web application. It's expense tracker, with small HTTP API. Don't take too many of these ideas to production 🙃 You can play with it through expenses.http.
First suite of test to check out is test_repos. It uses test containers to spin up Postgres database and checks if repository works as promised. It's a good tool for more complex SQL queries, or testing against concurrency issues.
Next one is test_http_api. It includes database trick from previous suite, but also spins up API. Explored idea here is how to keep tests like these easy to read, and not a chore to write (at least, after the first one).
Final one is test_e2e. We are spinning up whole application, and running tests against that. To make things even more interesting, we are stubing external API for better reliability. This checks that our application starts correctly, and that all the components work together. It's certainly more complex, not as quick to write, nor run. Use them sparingly, to make sure that crucial parts of your application work as expected. These could also be named smoke tests.
- Go 1.21
- Docker Desktop 24+
docker compose upRun unit tests:
go test ./...Run e2e tests:
PKGS=$(git grep --files-with-matches "//go:build e2e_tests" -- "*.go" | xargs dirname | sed 's,^,./,g' | sort -u)
go test -tags=e2e_tests $PKGS