Remove unnessary early header write

api/api.go

@@ -12,7 +12,7 @@ import (
 // always returns a router for the newest version of our API. We
 // use gorilla/mux because it is more convenient than net/http, e.g.
 // when extracting path parameters.
-func NewRouter() *mux.Router {
+func NewRouter() http.Handler {
 	router := mux.NewRouter()
 	// this can later be restricted to a specific host with
 	// `router.Host(...)` and to HTTPS with `router.Schemes("https")`

api/health.go

@@ -7,7 +7,6 @@ import (
 // Health tries to respond that the server is alive.
 // If it is not, the response won't reach the client.
 func Health(writer http.ResponseWriter, _ *http.Request) {
-	writer.WriteHeader(http.StatusOK)
 	writeJson(
 		writer,
 		Message{"I'm alive!"},

api/health_test.go

@@ -19,5 +19,6 @@ func TestHealthRoute(t *testing.T) {
 	_ = json.Unmarshal(recorder.Body.Bytes(), &result)
 
 	assert.Equal(t, http.StatusOK, recorder.Code)
+	assert.Equal(t, "application/json", recorder.Header().Get("Content-Type"))
 	assert.Equal(t, "I'm alive!", result.Message)
 }