feat(select): add test code to README

docs(concurrency): add code block to README
test(concurrency):  add test and benchmark for website checker

Author: yuanyu90221

concurrency/REAME.md

@@ -6,3 +6,43 @@
 
 golang 採用 user level 的執行緒，並且由 goroutine scheduler 來分配執行任務給 os level 的執行序來執行
 
+## code
+
+```golang
+func TestCheckWebsites(t *testing.T) {
+	websites := []string{
+		"http://google.com",
+		"http://blog.gypsydave5.com",
+		"waat://furhurerme.geds",
+	}
+	want := map[string]bool{
+		"http://google.com":          true,
+		"http://blog.gypsydave5.com": true,
+		"waat://furhurerme.geds":     false,
+	}
+
+	got := CheckWebsites(mockWebsiteChecker, websites)
+	if !reflect.DeepEqual(want, got) {
+		t.Fatalf("want %v, got %v", want, got)
+	}
+}
+
+func slowSubWebsiteChecker(_ string) bool {
+	time.Sleep(20 * time.Millisecond)
+	return true
+}
+
+func BenchmarkCheckWebsites(b *testing.B) {
+	urls := make([]string, 100)
+	for i := 0; i < len(urls); i++ {
+		urls[i] = "a url"
+	}
+	for b.Loop() {
+		CheckWebsites(slowSubWebsiteChecker, urls)
+	}
+}
+```
+
+## This test would be add later
+
+This is for test ai commit

select/README.md

@@ -5,3 +5,45 @@
 
 這時可以透過 select 語法來最有效的等候多個 channel 的傳遞資訊
 
+## code
+
+```golang
+func TestRacer(t *testing.T) {
+	t.Run("compares speeds of servers, returning the url of the fastest one", func(t *testing.T) {
+		slowServer := makeDelayServer(5 * time.Millisecond)
+		fastServer := makeDelayServer(0 * time.Millisecond)
+		defer slowServer.Close()
+		defer fastServer.Close()
+		slowURL := slowServer.URL
+		fastURL := fastServer.URL
+		want := fastURL
+		got, err := Racer(slowURL, fastURL)
+		if err != nil {
+			t.Errorf("error should be nit")
+		}
+		if got != want {
+			t.Errorf("got %q, want %q", got, want)
+		}
+	})
+	t.Run("returns an error if a server doesn't respond within the specified time", func(t *testing.T) {
+		server := makeDelayServer(25 * time.Millisecond)
+
+		defer server.Close()
+
+		_, err := ConfigurableRacer(server.URL, server.URL, 20*time.Millisecond)
+
+		if err == nil {
+			t.Error("expected an error but didn't get one")
+		}
+	})
+}
+
+func makeDelayServer(timeout time.Duration) *httptest.Server {
+	return httptest.NewServer(http.HandlerFunc(
+		func(w http.ResponseWriter, r *http.Request) {
+			time.Sleep(timeout)
+			w.WriteHeader(http.StatusOK)
+		},
+	))
+}
+```

select/select.go

@@ -22,12 +22,6 @@ func Racer(a, b string) (string, error) {
 	return ConfigurableRacer(a, b, tenSecondTimeout)
 }
 
-func measureResponseTime(url string) time.Duration {
-	start := time.Now()
-	http.Get(url)
-	return time.Since(start)
-}
-
 func ping(url string) chan struct{} {
 	ch := make(chan struct{})
 	go func() {