Fix route handling on OTEL httpmetrics (#199)

## Rationale 

The route field wasn't resolved properly. Here we consider the entire list of used routes, similarly how it's done with `New`.

## Changes
* Consider all route patterns to set the route attribute
* Add more tests

## Meta
[W-13781478](https://gus.lightning.force.com/a07EE00001WSFXiYAP)

hmiddleware/httpmetrics/httpmetrics_v2.go → hmiddleware/httpmetrics/httpmetrics_otel.go

@@ -3,6 +3,7 @@ package httpmetrics
 import (
 	"net/http"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/heroku/x/go-kit/metrics"
@@ -51,8 +52,7 @@ func NewOTEL(p metrics.Provider) func(http.Handler) http.Handler {
 			if ctx.Value(chi.RouteCtxKey) != nil {
 				rtCtx := chi.RouteContext(ctx)
 				if len(rtCtx.RoutePatterns) > 0 {
-					// pick last route pattern as it is the one chi used
-					route := rtCtx.RoutePatterns[len(rtCtx.RoutePatterns)-1]
+					route := getRouteAsString(rtCtx.RoutePatterns)
 					kv := []string{routeKey, route}
 					labels = append(labels, kv...)
 				}
@@ -70,3 +70,11 @@ func NewOTEL(p metrics.Provider) func(http.Handler) http.Handler {
 		})
 	}
 }
+
+func getRouteAsString(patterns []string) string {
+	var result string
+	for _, pattern := range patterns {
+		result += pattern
+	}
+	return strings.ReplaceAll(result, "/*/", "/")
+}

hmiddleware/httpmetrics/httpmetrics_otel_test.go

@@ -0,0 +1,158 @@
+package httpmetrics
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/go-chi/chi"
+
+	"github.com/heroku/x/go-kit/metrics/testmetrics"
+)
+
+func TestOTELMiddleware(t *testing.T) {
+	p := testmetrics.NewProvider(t)
+
+	next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	})
+
+	r := httptest.NewRequest("GET", "http://example.org/foo/bar", nil)
+	w := httptest.NewRecorder()
+
+	hand := NewOTEL(p)(next)
+	hand.ServeHTTP(w, r)
+
+	p.CheckObservationCount("http.server.duration.http.request.method:GET:url.scheme:http:server.address:example.org", 1)
+}
+
+func TestOTELResponseStatus(t *testing.T) {
+	p := testmetrics.NewProvider(t)
+
+	next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(502)
+	})
+
+	r := httptest.NewRequest("GET", "http://example.org/foo/bar", nil)
+	w := httptest.NewRecorder()
+
+	hand := NewOTEL(p)(next)
+	hand.ServeHTTP(w, r)
+
+	p.CheckObservationCount("http.server.duration.http.request.method:GET:http.response.status_code:502:url.scheme:http:server.address:example.org", 1)
+}
+
+func TestOTELChi(t *testing.T) {
+	p := testmetrics.NewProvider(t)
+
+	next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	})
+
+	r := httptest.NewRequest("GET", "http://example.org/foo/bar", nil)
+
+	rctx := chi.NewRouteContext()
+	rctx.RoutePatterns = []string{"/*", "/apps/{foo_id}/bars/{bar_id}"}
+	r = r.WithContext(context.WithValue(r.Context(), chi.RouteCtxKey, rctx))
+
+	w := httptest.NewRecorder()
+
+	hand := NewOTEL(p)(next)
+	hand.ServeHTTP(w, r)
+
+	p.CheckObservationCount("http.server.duration.http.request.method:GET:http.route:/apps/{foo_id}/bars/{bar_id}:url.scheme:http:server.address:example.org", 1)
+
+}
+
+func TestOTELNestedChiRouters(tt *testing.T) {
+
+	cases := []struct {
+		name        string
+		url         string
+		outerRoute  string
+		innerRouter func(t *testing.T) *chi.Mux
+		observation string
+	}{
+		{
+			name:       "inner outer",
+			url:        "http://example.org/hello/world",
+			outerRoute: "/",
+			innerRouter: func(t *testing.T) *chi.Mux {
+				r := chi.NewRouter()
+				r.Get("/hello/{name}", func(w http.ResponseWriter, r *http.Request) {
+					name := chi.URLParam(r, "id")
+					if _, err := io.WriteString(w, fmt.Sprintf("Hello %s!", name)); err != nil {
+						t.Fatal("unexpected error", err)
+					}
+				})
+				return r
+			},
+			observation: "http.server.duration.http.request.method:GET:http.response.status_code:200:http.route:/hello/{name}:url.scheme:http:server.address:example.org",
+		},
+		{
+			name:       "outer inner",
+			url:        "http://example.org/hello/world",
+			outerRoute: "/hello/{name}",
+			innerRouter: func(t *testing.T) *chi.Mux {
+				r := chi.NewRouter()
+				r.Get("/", func(w http.ResponseWriter, r *http.Request) {
+					name := chi.URLParam(r, "id")
+					if _, err := io.WriteString(w, fmt.Sprintf("Hello %s!", name)); err != nil {
+						t.Fatal("unexpected error", err)
+					}
+				})
+				return r
+			},
+			observation: "http.server.duration.http.request.method:GET:http.response.status_code:200:http.route:/hello/{name}/:url.scheme:http:server.address:example.org",
+		},
+		{
+			name:       "inner outer star",
+			url:        "http://example.org/hello/world/1",
+			outerRoute: "/",
+			innerRouter: func(t *testing.T) *chi.Mux {
+				r := chi.NewRouter()
+				r.Get("/hello/{name}/*", func(w http.ResponseWriter, r *http.Request) {
+					name := chi.URLParam(r, "id")
+					if _, err := io.WriteString(w, fmt.Sprintf("Hello %s!", name)); err != nil {
+						t.Fatal("unexpected error", err)
+					}
+				})
+				return r
+			},
+			observation: "http.server.duration.http.request.method:GET:http.response.status_code:200:http.route:/hello/{name}/*:url.scheme:http:server.address:example.org",
+		},
+		{
+			name:       "slash slash",
+			url:        "http://example.org/",
+			outerRoute: "/",
+			innerRouter: func(t *testing.T) *chi.Mux {
+				r := chi.NewRouter()
+				r.Get("/", func(w http.ResponseWriter, r *http.Request) {
+					name := chi.URLParam(r, "id")
+					if _, err := io.WriteString(w, fmt.Sprintf("Hello %s!", name)); err != nil {
+						t.Fatal("unexpected error", err)
+					}
+				})
+				return r
+			},
+			observation: "http.server.duration.http.request.method:GET:http.response.status_code:200:http.route:/:url.scheme:http:server.address:example.org",
+		},
+	}
+
+	for _, test := range cases {
+		test := test
+		tt.Run(test.name, func(t *testing.T) {
+			p := testmetrics.NewProvider(t)
+			outer := chi.NewRouter()
+			outer.Use(NewOTEL(p))
+			outer.Mount(test.outerRoute, test.innerRouter(t))
+
+			r := httptest.NewRequest("GET", test.url, nil)
+			w := httptest.NewRecorder()
+			outer.ServeHTTP(w, r)
+
+			p.CheckObservationCount(test.observation, 1)
+		})
+	}
+}