Instrumentation: Define handlers for requests that are not handled with named handlers (#50613)

Signed-off-by: bergquist <carl.bergquist@gmail.com>

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>
Co-authored-by: Sofia Papagiannaki <1632407+papagian@users.noreply.github.com>

pkg/middleware/request_test.go

@@ -0,0 +1,40 @@
+package middleware
+
+import (
+	"context"
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCanGetRouteNameFromContext(t *testing.T) {
+	tcs := []struct {
+		namedHandler string
+		path         string
+
+		expected string
+	}{
+		{namedHandler: "", path: "/public/img/apple-touch-icon.png", expected: "public-assets"},
+		{namedHandler: "", path: "/favicon.ico", expected: "public-assets"},
+		{namedHandler: "", path: "/robots.txt", expected: "/robots.txt"},
+		{namedHandler: "", path: "/debug/pprof/heap", expected: "/debug/pprof-handlers"},
+		{namedHandler: "", path: "/debug/pprof/allocs", expected: "/debug/pprof-handlers"},
+		{namedHandler: "", path: "/debug/pprof/threadcreate", expected: "/debug/pprof-handlers"},
+		{namedHandler: "/api/dashboard/:uid", path: "/api/dashboard/ddfgeasdfr", expected: "/api/dashboard/:uid"},
+		{namedHandler: "", path: "/metrics", expected: "/metrics"},
+	}
+
+	for _, tc := range tcs {
+		req, err := http.NewRequest(http.MethodPost, "https://ops.grafana.net"+tc.path, nil)
+
+		if tc.namedHandler != "" {
+			req = req.WithContext(context.WithValue(context.Background(), routeOperationNameKey, tc.namedHandler))
+		}
+
+		assert.NoError(t, err)
+
+		handler, _ := routeOperationName(req)
+		assert.Equal(t, tc.expected, handler)
+	}
+}