fix: refactor error handling and testing infrastructure

- Handle the error returned by `io.WriteString` in `basicHelloHandler` function

Signed-off-by: appleboy <appleboy.tw@gmail.com>

gofight_test.go

@@ -9,7 +9,7 @@ import (
 )
 
 func basicHelloHandler(w http.ResponseWriter, r *http.Request) {
-	io.WriteString(w, "Hello World")
+	_, _ = io.WriteString(w, "Hello World")
 }
 
 func basicEngine() http.Handler {