这个要熟悉原理，要能写。。

但现在。。。。。

注意，没有main函数，以_test.go结尾，命令go test -v

package mainimport (	"testing"	"net/http")const checkMark = " OK! "const ballotX = " ERROR! "	func TestDownload(t *testing.T) {	url := "http://localhost:8000/test.html"	statusCode := 200		t.Log("Given the need to test downloading content.")	{		t.Logf("\tWhen checking \"%s\" for status code \"%d\"", url, statusCode)		{			resp, err := http.Get(url)			if err != nil {				t.Fatal("\tShould be able to make the Get call.", ballotX, err)			}			t.Log("\t\tShould be able to make the Get call.", checkMark)			defer resp.Body.Close()						if resp.StatusCode == statusCode {				t.Logf("\t\tShould receive a \"%d\" status, %v", statusCode, checkMark)			} else {				t.Errorf("\t\tShould receive a \"%d\" status. %v %v", statusCode, ballotX, resp.StatusCode)			}		}	}}