test(metrics): add middleware test

go.mod

@@ -242,6 +242,7 @@ require (
 	github.com/klauspost/pgzip v1.2.6 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
 	github.com/kr/text v0.2.0 // indirect
+	github.com/kylelemons/godebug v1.1.0 // indirect
 	github.com/libdns/libdns v0.2.2 // indirect
 	github.com/magiconair/properties v1.8.7 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect

routers/common/middleware.go

@@ -165,7 +165,7 @@ func RouteMetrics() func(h http.Handler) http.Handler {
 			route := chi.RouteContext(req.Context()).RoutePattern()
 			code := strconv.Itoa(m.WrittenStatus())
 			reqDurationHistogram.WithLabelValues(req.Method, code, route).Observe(time.Since(start).Seconds())
-			respSizeHistogram.WithLabelValues(req.Method, code, route).Observe(float64(m.Size()))
+			respSizeHistogram.WithLabelValues(req.Method, code, route).Observe(float64(m.WrittenSize()))
 			size := req.ContentLength
 			if size < 0 {
 				size = 0

routers/common/middleware_test.go

@@ -1,4 +1,4 @@
-package common_test
+package common
 
 import (
 	"net/http"
@@ -6,25 +6,33 @@ import (
 	"testing"
 	"time"
 
-	"code.gitea.io/gitea/routers/common"
-
 	"github.com/go-chi/chi/v5"
+	"github.com/prometheus/client_golang/prometheus/testutil"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
 func TestMetricsMiddlewere(t *testing.T) {
-
-	middleware := common.RouteMetrics()
+	middleware := RouteMetrics()
 	r := chi.NewRouter()
 	r.Use(middleware)
 	r.Get("/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte("test"))
 		time.Sleep(5 * time.Millisecond)
 	}))
-
 	testServer := httptest.NewServer(r)
-
+	// Check all defined metrics
+	verify := func(i int) {
+		assert.Equal(t, testutil.CollectAndCount(reqDurationHistogram, "http_server_request_duration"), i)
+		assert.Equal(t, testutil.CollectAndCount(reqSizeHistogram, "http_server_request_body_size"), i)
+		assert.Equal(t, testutil.CollectAndCount(respSizeHistogram, "http_server_response_body_size"), i)
+		assert.Equal(t, testutil.CollectAndCount(reqInflightGauge, "http_server_active_requests"), i)
+	}
+
+	// Check they don't exist before making a request
+	verify(0)
 	_, err := http.Get(testServer.URL)
 	require.NoError(t, err)
-
+	// Check they do exist after making the request
+	verify(1)
 }