diff --git a/progress_go1.7_test.go b/progress_go1.7_test.go
index 7ba7933..e709675 100644
--- a/progress_go1.7_test.go
+++ b/progress_go1.7_test.go
@@ -6,6 +6,7 @@
 	"context"
 	"fmt"
 	"math/rand"
+	"sync"
 	"testing"
 	"time"
 
@@ -16,21 +17,37 @@
 	ctx, cancel := context.WithCancel(context.Background())
 	shutdown := make(chan struct{})
 	p := mpb.New().WithContext(ctx).ShutdownNotify(shutdown)
+
+	var wg sync.WaitGroup
+	total := 100
 	numBars := 3
+	wg.Add(numBars)
 
 	for i := 0; i < numBars; i++ {
 		name := fmt.Sprintf("Bar#%d:", i)
-		bar := p.AddBar(100).PrependName(name, len(name), 0)
+		bar := p.AddBarWithID(i, int64(total)).PrependName(name, len(name), 0)
 
 		go func() {
-			for i := 0; i < 10000; i++ {
+			defer func() {
+				// fmt.Printf("%s done\n", name)
+				wg.Done()
+			}()
+			for i := 0; i < total; i++ {
+				select {
+				case <-ctx.Done():
+					return
+				default:
+				}
+				time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
 				bar.Incr(1)
-				time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
 			}
 		}()
 	}
 
-	cancel()
+	time.AfterFunc(300*time.Millisecond, cancel)
+
+	wg.Wait()
+	p.Stop()
 
 	select {
 	case <-shutdown:
diff --git a/progress_test.go b/progress_test.go
index 5e7a729..6dacba6 100644
--- a/progress_test.go
+++ b/progress_test.go
@@ -102,21 +102,39 @@
 	cancel := make(chan struct{})
 	shutdown := make(chan struct{})
 	p := mpb.New().WithCancel(cancel).ShutdownNotify(shutdown)
+
+	var wg sync.WaitGroup
+	total := 100
 	numBars := 3
+	wg.Add(numBars)
 
 	for i := 0; i < numBars; i++ {
 		name := fmt.Sprintf("Bar#%d:", i)
-		bar := p.AddBar(100).PrependName(name, len(name), 0)
+		bar := p.AddBarWithID(i, int64(total)).PrependName(name, len(name), 0)
 
 		go func() {
-			for i := 0; i < 10000; i++ {
+			defer func() {
+				// fmt.Printf("%s done\n", name)
+				wg.Done()
+			}()
+			for i := 0; i < total; i++ {
+				select {
+				case <-cancel:
+					return
+				default:
+				}
+				time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
 				bar.Incr(1)
-				time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
 			}
 		}()
 	}
 
-	close(cancel)
+	time.AfterFunc(300*time.Millisecond, func() {
+		close(cancel)
+	})
+
+	wg.Wait()
+	p.Stop()
 
 	select {
 	case <-shutdown:
@@ -124,3 +142,57 @@
 		t.Error("ProgressBar didn't stop")
 	}
 }
+
+func TestWithNilCancel(t *testing.T) {
+	defer func() {
+		if p := recover(); p != nil {
+			if msg, ok := p.(string); ok && msg == "nil cancel channel" {
+				return
+			}
+			t.Errorf("Expected nil channel panic, got: %+v", p)
+		}
+	}()
+	_ = mpb.New().WithCancel(nil)
+}
+
+func TestFormat(t *testing.T) {
+	var buf bytes.Buffer
+	cancel := make(chan struct{})
+	shutdown := make(chan struct{})
+	customFormat := "╢▌▌░╟"
+	p := mpb.New().Format(customFormat)
+	p.WithCancel(cancel)
+	p.ShutdownNotify(shutdown)
+	p.SetOut(&buf)
+	bar := p.AddBar(100).TrimLeftSpace().TrimRightSpace()
+
+	go func() {
+		for i := 0; i < 100; i++ {
+			bar.Incr(1)
+			time.Sleep(10 * time.Millisecond)
+			if i == 42 {
+				close(cancel)
+			}
+		}
+	}()
+
+	// p.Stop()
+	// time.Sleep(300 * time.Millisecond)
+
+	// gotBar := strings.TrimSpace(buf.String())
+	gotBar := buf.String()
+	seen := make(map[rune]bool)
+	for _, r := range gotBar {
+		if !seen[r] {
+			seen[r] = true
+		}
+	}
+	fmt.Println(gotBar)
+	for r, _ := range seen {
+		fmt.Printf("%#U\n", r)
+	}
+	// expectBar := "╢▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌▌╟"
+	// if gotBar != expectBar {
+	// 	t.Errorf("Expected for")
+	// }
+}