golang-testing

Define a slice of anonymous structs containing test name, inputs, and expected outputs, then loop over it calling t.Run for each case. This pattern covers many scenarios with minimal code and is the standard Go testing idiom.

Write a function starting with Fuzz that takes *testing.F, add seed corpus entries with f.Add, then define the fuzz function with f.Fuzz. Run it with go test -fuzz=FuzzName -fuzztime=30s; fuzzing requires Go 1.18 or later.

Define an interface for the dependency, then create a mock struct with function fields matching each interface method. Inject the mock into the code under test and set the function fields to return canned responses per test case.

Yes, run go test -coverprofile=coverage.out ./... to generate a coverage profile, then use go tool cover -html=coverage.out for a browser view or -func for per-function percentages. Combine with -race for race detection.

Testing private functions couples tests to implementation details, making refactors break tests unnecessarily. Test through the public API instead, which verifies behavior rather than internal structure.

Use httptest.NewRequest to build a request and httptest.NewRecorder to capture the response, then call the handler directly. Assert on the recorder's status code and body, optionally using table-driven tests for multiple endpoints.