Initial delivery of metrics code (#81)

* Initial delivery of metrics code

* Fix build issues

* Fix build issue with go vet

vendor/github.com/prometheus/common/route/route_test.go

@@ -0,0 +1,76 @@
+package route
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestRedirect(t *testing.T) {
+	router := New().WithPrefix("/test/prefix")
+	w := httptest.NewRecorder()
+	r, err := http.NewRequest("GET", "http://localhost:9090/foo", nil)
+	if err != nil {
+		t.Fatalf("Error building test request: %s", err)
+	}
+
+	router.Redirect(w, r, "/some/endpoint", http.StatusFound)
+	if w.Code != http.StatusFound {
+		t.Fatalf("Unexpected redirect status code: got %d, want %d", w.Code, http.StatusFound)
+	}
+
+	want := "/test/prefix/some/endpoint"
+	got := w.Header()["Location"][0]
+	if want != got {
+		t.Fatalf("Unexpected redirect location: got %s, want %s", got, want)
+	}
+}
+
+func TestContext(t *testing.T) {
+	router := New()
+	router.Get("/test/:foo/", func(w http.ResponseWriter, r *http.Request) {
+		want := "bar"
+		got := Param(r.Context(), "foo")
+		if want != got {
+			t.Fatalf("Unexpected context value: want %q, got %q", want, got)
+		}
+	})
+
+	r, err := http.NewRequest("GET", "http://localhost:9090/test/bar/", nil)
+	if err != nil {
+		t.Fatalf("Error building test request: %s", err)
+	}
+	router.ServeHTTP(nil, r)
+}
+
+func TestInstrumentation(t *testing.T) {
+	var got string
+	cases := []struct {
+		router *Router
+		want   string
+	}{
+		{
+			router: New(),
+			want:   "",
+		}, {
+			router: New().WithInstrumentation(func(handlerName string, handler http.HandlerFunc) http.HandlerFunc {
+				got = handlerName
+				return handler
+			}),
+			want: "/foo",
+		},
+	}
+
+	for _, c := range cases {
+		c.router.Get("/foo", func(w http.ResponseWriter, r *http.Request) {})
+
+		r, err := http.NewRequest("GET", "http://localhost:9090/foo", nil)
+		if err != nil {
+			t.Fatalf("Error building test request: %s", err)
+		}
+		c.router.ServeHTTP(nil, r)
+		if c.want != got {
+			t.Fatalf("Unexpected value: want %q, got %q", c.want, got)
+		}
+	}
+}