redone the test and go codes

main.go

@@ -1,20 +1,7 @@
 package main
 
-import (
-   "log"
-   "net/http"
-)
-
-type Server struct{}
-
-func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-   w.WriteHeader(http.StatusOK)
-   w.Header().Set("Content-Type", "application/json")
-   w.Write([]byte(`{"message": "Hello world"}`))
-}
+import "fmt"
 
 func main() {
-   s := &Server{}
-   http.Handle("/", s)
-   log.Fatal(http.ListenAndServe(":8080", nil))
+	fmt.Println("Hello World")
 }

main_test.go

@@ -1,20 +1,30 @@
+
 package main
 
 import (
-   "log"
-   "net/http"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+	"testing"
 )
 
-type Server struct{}
+func TestHelloWorld(t *testing.T) {
+	rescueStdout := os.Stdout
+	r, w, _ := os.Pipe()
+	os.Stdout = w
 
-func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-   w.WriteHeader(http.StatusOK)
-   w.Header().Set("Content-Type", "application/json")
-   w.Write([]byte(`{"message": "hello world"}`))
-}
+	main()
 
-func main() {
-   s := &Server{}
-   http.Handle("/", s)
-   log.Fatal(http.ListenAndServe(":8080", nil))
+	w.Close()
+	out, _ := ioutil.ReadAll(r)
+	os.Stdout = rescueStdout
+
+	fmt.Println(string(out))
+
+	var outputString string = string(out)
+
+	if strings.TrimSpace(outputString) != "Hello World" {
+		t.Errorf("Expected %s, got %s", "Hello World", out)
+	}
 }