An integration test checks a sequence of operations through components working together, rather than testing one function in isolation. For a cache, write a value before reading it: the test then checks observable behavior without depending on how storage is implemented. For a service, run the server and make requests as a client would. section 7.1.3 section 10.5 section 10.5.2
Test a habit-tracker flow
Start the gRPC server with its repository, connect a generated client, then create two habits and list them. Check that both appear. Try creating a habit with a blank name and check for the expected invalid-argument error. Further calls can use the ID returned by creation to tick a habit and verify its status. This exercises the network API and service layers together. section 10.5 section 10.5.2 section 10.7.6
Keep the test repeatable and useful:
- Let the listener select a free port, start the server while the test makes calls, and stop it when the test ends. section 10.5.2
- Assert results through the client. Check generated IDs exist, but do not compare unpredictable ID values with fixed strings. section 10.5.2
- Make list responses deterministic where possible; a defined order makes expected results simpler to check. section 10.5.1
- Use the in-memory repository while it serves the test. With a real database, decide whether to run a local instance or replace it with a mock. section 10.5.2
Listing 10.26 integration_test.go: Starting the service
func TestIntegration(t *testing.T) {
grpcServ := newServer(t)
listener, err := net.Listen("tcp", "")
require.NoError(t, err)
wg := sync.WaitGroup{}
wg.Add(1)
go func() {
defer wg.Done()
err = grpcServ.Serve(listener)
require.NoError(t, err)
}()
defer func() {
// terminate the GRPC server
grpcServ.Stop()
// when that is done, and no error were caught, we can end this test
wg.Wait() #1
}()
}
func newServer(t *testing.T) *grpc.Server {
t.Helper() #2
s := server.New(repository.New(t), t) #3
grpcServer := grpc.NewServer(
grpc.UnaryInterceptor(timerInterceptor(s.lgr)))
api.RegisterHabitsServer(grpcServer, s)
reflection.Register(grpcServer)
return grpcServer
}
The server setup shows a test listener, a running gRPC service, and shutdown at the end of the test. section 10.5.2
Run the full suite with `go test -v ./...`. If the integration scenario is too costly for a lightweight run, check `testing.Short()` and skip it under `go test -v -short ./...`. Keep focused unit tests too: a handler test with a prepared URL parameter does not establish that the complete HTTP request flow works. section 10.5.2 section 11.3.1
