default constructor

src/device/input/input.go

@@ -1,5 +1,9 @@
 package input
 
 type Input interface {
-	Read() []byte
+	Read() []Button
+}
+
+func New() Input {
+	return NewRandom('a', 'g')
 }

src/device/input/input_test.go

@@ -0,0 +1,7 @@
+package input
+
+import "testing"
+
+func TestInput(t *testing.T) {
+	var _ Input = &Random{}
+}

src/device/input/random.go

@@ -18,7 +18,7 @@ type Random struct {
 
 func NewRandom(start, stop byte) *Random {
 	rand.Seed(time.Now().UnixNano())
-	return &Random{start: start, stop: stop + 1}
+	return &Random{start: start, stop: stop}
 }
 
 func (r *Random) Read() []Button {
@@ -30,7 +30,7 @@ func (r *Random) Read() []Button {
 		r.down = r.down[:0]
 		return was
 	} else {
-		c := Button{Char: r.start + byte(rand.Int()%int(r.stop-r.start)), Down: true}
+		c := Button{Char: r.start + byte(rand.Int()%int(1+r.stop-r.start)), Down: true}
 		r.down = append(r.down, c)
 		return []Button{c}
 	}

src/device/output/output.go

@@ -1,6 +1,12 @@
 package output
 
+import "os"
+
 type Output interface {
 	Close()
 	Press(...Key)
 }
+
+func New() Output {
+	return NewWriter(os.Stderr)
+}