fix divide-by-zero issue in progress tracker's ETA function (#67)

progress/tracker.go

@@ -34,11 +34,11 @@ func (t *Tracker) ETA() time.Duration {
 		return t.ExpectedDuration - timeTaken
 	}
 
-	pDone := t.PercentDone()
+	pDone := int64(t.PercentDone())
 	if pDone == 0 {
 		return time.Duration(0)
 	}
-	return time.Duration((int64(timeTaken) / int64(pDone)) * int64(100-pDone))
+	return time.Duration((int64(timeTaken) / pDone) * (100 - pDone))
 }
 
 // Increment updates the current value of the task being tracked.
@@ -66,6 +66,9 @@ func (t *Tracker) MarkAsDone() {
 
 // PercentDone returns the currently completed percentage value.
 func (t *Tracker) PercentDone() float64 {
+	if t.Total == 0 {
+		return 0
+	}
 	return float64(t.value) * 100.0 / float64(t.Total)
 }
 

progress/tracker_test.go

@@ -11,7 +11,10 @@ func TestTracker_ETA(t *testing.T) {
 	timeDelayUnit := time.Millisecond
 	timeDelay := timeDelayUnit * 25
 
-	tracker := Tracker{Total: 100}
+	tracker := Tracker{}
+	assert.Equal(t, time.Duration(0), tracker.ETA())
+
+	tracker.Total = 100
 	tracker.start()
 	assert.Equal(t, time.Duration(0), tracker.ETA())
 	time.Sleep(timeDelay)
@@ -65,7 +68,10 @@ func TestTracker_MarkAsDone(t *testing.T) {
 }
 
 func TestTracker_PercentDone(t *testing.T) {
-	tracker := Tracker{Total: 100}
+	tracker := Tracker{}
+	assert.Equal(t, 0.00, tracker.PercentDone())
+
+	tracker.Total = 100
 	assert.Equal(t, 0.00, tracker.PercentDone())
 
 	for idx := 1; idx <= 100; idx++ {