added test round tripper

http/test_round_tripper.go

@@ -0,0 +1,15 @@
+package http
+
+import (
+	"github.com/stretchr/testify/mock"
+	"net/http"
+)
+
+type TestRoundTripper struct {
+	mock.Mock
+}
+
+func (t *TestRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	args := t.Called(req)
+	return args.Get(0).(*http.Response), args.Error(1)
+}