diff --git a/draw_test.go b/draw_test.go
new file mode 100644
index 0000000..a7555fa
--- /dev/null
+++ b/draw_test.go
@@ -0,0 +1,112 @@
+package mpb
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestFillBar(t *testing.T) {
+	tests := []struct {
+		termWidth int
+		barWidth  int
+		total     int64
+		current   int64
+		barRefill *Refill
+		want      []byte
+	}{
+		{
+			termWidth: 1,
+			barWidth:  100,
+			want:      []byte{},
+		},
+		{
+			termWidth: 2,
+			barWidth:  100,
+			total:     100,
+			current:   20,
+			want:      []byte("[]"),
+		},
+		{
+			termWidth: 20,
+			barWidth:  100,
+			total:     100,
+			current:   20,
+			want:      []byte("[===>--------------]"),
+		},
+		{
+			termWidth: 50,
+			barWidth:  100,
+			total:     100,
+			current:   20,
+			want:      []byte("[=========>--------------------------------------]"),
+		},
+		{
+			termWidth: 100,
+			barWidth:  100,
+			total:     100,
+			current:   0,
+			want:      []byte("[--------------------------------------------------------------------------------------------------]"),
+		},
+		{
+			termWidth: 100,
+			barWidth:  100,
+			total:     100,
+			current:   1,
+			want:      []byte("[>-------------------------------------------------------------------------------------------------]"),
+		},
+		{
+			termWidth: 100,
+			barWidth:  100,
+			total:     100,
+			current:   40,
+			want:      []byte("[======================================>-----------------------------------------------------------]"),
+		},
+		{
+			termWidth: 100,
+			barWidth:  100,
+			total:     100,
+			current:   40,
+			barRefill: &Refill{'+', 32},
+			want:      []byte("[+++++++++++++++++++++++++++++++=======>-----------------------------------------------------------]"),
+		},
+		{
+			termWidth: 100,
+			barWidth:  100,
+			total:     100,
+			current:   99,
+			want:      []byte("[================================================================================================>-]"),
+		},
+		{
+			termWidth: 100,
+			barWidth:  100,
+			total:     100,
+			current:   100,
+			want:      []byte("[==================================================================================================]"),
+		},
+	}
+
+	prependWs := newWidthSync(nil, 1, 0)
+	appendWs := newWidthSync(nil, 1, 0)
+	for _, test := range tests {
+		s := newTestState()
+		s.width = test.barWidth
+		s.total = test.total
+		s.current = test.current
+		if test.barRefill != nil {
+			s.refill = test.barRefill
+		}
+		got := draw(s, test.termWidth, prependWs, appendWs)
+		if !reflect.DeepEqual(test.want, got) {
+			t.Errorf("Want: %q, Got: %q\n", test.want, got)
+		}
+	}
+}
+
+func newTestState() *state {
+	s := &state{
+		trimLeftSpace:  true,
+		trimRightSpace: true,
+	}
+	s.updateFormat("[=>-]")
+	return s
+}