Merge pull request #15 from yunginnanet/closed-rate-fix

Fix: Rate method returns zero after sp is closed + add test

Author: yunginnanet

Diff for: speedometer/speedometer.go

@@ -209,7 +209,7 @@ func (s *Speedometer) Close() error {
 // Rate returns the bytes per second rate at which data is being written to the underlying writer.
 func (s *Speedometer) Rate() float64 {
 	if s.internal.closed.Load() {
-		return float64(s.Total()) / s.internal.duration.Load().Seconds()
+		return 0
 	}
 	return float64(s.Total()) / time.Since(*s.internal.birth.Load()).Seconds()
 }

Diff for: speedometer/speedometer_test.go

@@ -152,6 +152,11 @@ func Test_Speedometer(t *testing.T) {
 			if closeErr := sp.Close(); closeErr != nil {
 				t.Errorf("wantErr: want %v, have %v", nil, closeErr)
 			}
+			t.Run("ZeroRateAfterClose", func(t *testing.T) {
+				if sp.Rate() != 0 {
+					t.Errorf("rate: want %f after 'Close' method, have %f", 0.0, sp.Rate())
+				}
+			})
 			err = <-errChan
 			if !errors.Is(err, io.ErrClosedPipe) {
 				t.Errorf("wantErr: want %v, have %v", io.ErrClosedPipe, err)