racer: test with timeout

racer/racer.go

@@ -8,7 +8,9 @@ import (
 
 var ErrRacerTimeout = errors.New("timeout")
 
-func Racer(a, b string, timeout time.Duration) (string, error) {
+const tenSecondTimeout = 10 * time.Second
+
+func ConfigurableRacer(a, b string, timeout time.Duration) (string, error) {
 	select {
 	// wait until channel closed
 	case <-ping(a):
@@ -20,6 +22,10 @@ func Racer(a, b string, timeout time.Duration) (string, error) {
 	}
 }
 
+func Racer(a, b string) (string, error) {
+	return ConfigurableRacer(a, b, tenSecondTimeout)
+}
+
 func ping(url string) chan struct{} {
 	ch := make(chan struct{})
 	go func() {

racer/racer_test.go

@@ -7,6 +7,12 @@ import (
 	"time"
 )
 
+type SpyRacerTimeout struct{}
+
+func (s *SpyRacerTimeout) Timeout() <-chan time.Time {
+	return time.After(1 * time.Millisecond)
+}
+
 func TestRacer(t *testing.T) {
 	t.Run("compares speeds of servers, returning the url of the fasted one", func(t *testing.T) {
 		slowServer := makeDelayedServer(20 * time.Millisecond)
@@ -19,7 +25,7 @@ func TestRacer(t *testing.T) {
 		fastURL := fastServer.URL
 
 		want := fastURL
-		got, _ := Racer(slowURL, fastURL, 10*time.Second)
+		got, _ := Racer(slowURL, fastURL)
 
 		if got != want {
 			t.Errorf("got %q, want %q", got, want)
@@ -27,13 +33,13 @@ func TestRacer(t *testing.T) {
 	})
 
 	t.Run("returns an error if a server doesn't respond within 10s", func(t *testing.T) {
-		serverA := makeDelayedServer(11 * time.Second)
+		serverA := makeDelayedServer(25 * time.Millisecond)
 		defer serverA.Close()
 
-		serverB := makeDelayedServer(11 * time.Second)
+		serverB := makeDelayedServer(25 * time.Millisecond)
 		defer serverB.Close()
 
-		_, err := Racer(serverA.URL, serverB.URL, 10*time.Second)
+		_, err := ConfigurableRacer(serverA.URL, serverB.URL, 20*time.Millisecond)
 		if err == nil {
 			t.Error("expected an error but didn't got one")
 		}