progress: fix overall tracker disappears in corner case (#246)

progress/progress.go

@@ -77,6 +77,15 @@ func (p *Progress) AppendTracker(t *Tracker) {
 		}
 		p.overallTracker.start()
 	}
+
+	// corner case: overall tracker is done, but new tracker is being added. We should recover it.
+	// issue: #245
+	if p.overallTracker.IsDone() {
+		p.overallTracker.mutex.Lock()
+		p.overallTracker.done = false
+		p.overallTracker.mutex.Unlock()
+	}
+
 	p.trackersInQueueMutex.Lock()
 	p.trackersInQueue = append(p.trackersInQueue, t)
 	p.trackersInQueueMutex.Unlock()

progress/progress_test.go

@@ -238,3 +238,11 @@ func TestProgress_Style(t *testing.T) {
 	assert.NotNil(t, p.Style())
 	assert.Equal(t, StyleDefault.Name, p.Style().Name)
 }
+
+func TestProgress_OverallTrackerDisappearsCase(t *testing.T) {
+	p := &Progress{}
+	p.overallTracker = &Tracker{Total: 1, done: true}
+	p.AppendTracker(&Tracker{Total: 1})
+
+	assert.Equal(t, false, p.overallTracker.IsDone())
+}