backport: potential worng total time in trace info from PR go-resty#1017

Author: git-hulk

request.go

@@ -907,13 +907,16 @@ func (r *Request) TraceInfo() TraceInfo {
 		RequestAttempt: r.Attempt,
 	}
 
-	// Calculate the total time accordingly,
-	// when connection is reused
-	if ct.gotConnInfo.Reused {
-		ti.TotalTime = ct.endTime.Sub(ct.getConn)
-	} else {
-		ti.TotalTime = ct.endTime.Sub(ct.dnsStart)
+	// Calculate the total time accordingly when connection is reused,
+	// and DNS start and get conn time may be zero if the request is invalid.
+	// See issue #1016.
+	requestStartTime := r.Time
+	if ct.gotConnInfo.Reused && !ct.getConn.IsZero() {
+		requestStartTime = ct.getConn
+	} else if !ct.dnsStart.IsZero() {
+		requestStartTime = ct.dnsStart
 	}
+	ti.TotalTime = ct.endTime.Sub(requestStartTime)
 
 	// Only calculate on successful connections
 	if !ct.connectDone.IsZero() {

request_test.go

@@ -2103,6 +2103,19 @@ func TestTraceInfoWithoutEnableTrace(t *testing.T) {
 	}
 }
 
+func TestTraceInfoWithInvalidRequest(t *testing.T) {
+	client := dc()
+	resp, err := client.R().EnableTrace().Get("unknown://url.com")
+	assertNotNil(t, err)
+	tr := resp.Request.TraceInfo()
+	assertEqual(t, true, tr.DNSLookup == 0)
+	assertEqual(t, true, tr.ConnTime == 0)
+	assertEqual(t, true, tr.TLSHandshake == 0)
+	assertEqual(t, true, tr.ServerTime == 0)
+	assertEqual(t, true, tr.ResponseTime == 0)
+	assertEqual(t, true, tr.TotalTime > 0 && tr.TotalTime < time.Second)
+}
+
 func TestTraceInfoOnTimeout(t *testing.T) {
 	client := dc()
 	client.SetHostURL("http://resty-nowhere.local").EnableTrace()