Improving error handling.

termdash.go

@@ -58,11 +58,12 @@ func RedrawInterval(t time.Duration) Option {
 	})
 }
 
-// InputErrorHandler is used to provide a function that will be called with all
-// input event errors. If not provided, input event errors are discarded.
-func InputErrorHandler(f func(error)) Option {
+// ErrorHandler is used to provide a function that will be called with all
+// errors that occur while the dashboard is running. If not provided, any
+// errors panic the application.
+func ErrorHandler(f func(error)) Option {
 	return option(func(td *termdash) {
-		td.inputErrorHandler = f
+		td.errorHandler = f
 	})
 }
 
@@ -119,7 +120,7 @@ type termdash struct {
 
 	// Options.
 	redrawInterval     time.Duration
-	inputErrorHandler  func(error)
+	errorHandler       func(error)
 	mouseSubscriber    func(*terminalapi.Mouse)
 	keyboardSubscriber func(*terminalapi.Keyboard)
 }
@@ -140,11 +141,13 @@ func newTermdash(t terminalapi.Terminal, c *container.Container, opts ...Option)
 	return td
 }
 
-// inputError forwards the input error to the error handler if one was
-// provided.
-func (td *termdash) inputError(err error) {
-	if td.inputErrorHandler != nil {
-		td.inputErrorHandler(err)
+// handleError forwards the error to the error handler if one was
+// provided or panics.
+func (td *termdash) handleError(err error) {
+	if td.errorHandler != nil {
+		td.errorHandler(err)
+	} else {
+		panic(err)
 	}
 }
 
@@ -223,12 +226,12 @@ func (td *termdash) processEvents(ctx context.Context) {
 		switch ev := event.(type) {
 		case *terminalapi.Keyboard:
 			if err := td.keyEvRedraw(ev); err != nil {
-				td.inputError(err)
+				td.handleError(err)
 			}
 
 		case *terminalapi.Mouse:
 			if err := td.mouseEvRedraw(ev); err != nil {
-				td.inputError(err)
+				td.handleError(err)
 			}
 
 		case *terminalapi.Resize:
@@ -240,7 +243,7 @@ func (td *termdash) processEvents(ctx context.Context) {
 			select {
 			case <-ctx.Done():
 			default:
-				td.inputError(ev.Error())
+				td.handleError(ev.Error())
 			}
 		}
 
@@ -261,10 +264,6 @@ func (td *termdash) start(ctx context.Context) error {
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
 
-	if err := td.periodicRedraw(); err != nil {
-		return err
-	}
-
 	// stops when stop() is called or the context expires.
 	go td.processEvents(ctx)
 

termdash_test.go

@@ -107,6 +107,7 @@ func TestRun(t *testing.T) {
 
 	tests := []struct {
 		desc   string
+		size   image.Point
 		opts   []Option
 		events []terminalapi.Event
 		// function to execute after the test case, can do additional comparison.
@@ -116,6 +117,7 @@ func TestRun(t *testing.T) {
 	}{
 		{
 			desc: "draws the dashboard until closed",
+			size: image.Point{60, 10},
 			opts: []Option{
 				RedrawInterval(1),
 			},
@@ -130,8 +132,21 @@ func TestRun(t *testing.T) {
 				return ft
 			},
 		},
+		{
+			desc: "fails when the widget doesn't draw",
+			size: image.Point{1, 1},
+			opts: []Option{
+				RedrawInterval(1),
+			},
+			want: func(size image.Point) *faketerm.Terminal {
+				ft := faketerm.MustNew(size)
+				return ft
+			},
+			wantErr: true,
+		},
 		{
 			desc: "resizes the terminal",
+			size: image.Point{60, 10},
 			opts: []Option{
 				RedrawInterval(1),
 			},
@@ -149,9 +164,9 @@ func TestRun(t *testing.T) {
 				return ft
 			},
 		},
-
 		{
 			desc: "forwards mouse events to container",
+			size: image.Point{60, 10},
 			opts: []Option{
 				RedrawInterval(1),
 			},
@@ -174,6 +189,7 @@ func TestRun(t *testing.T) {
 		},
 		{
 			desc: "forwards keyboard events to container",
+			size: image.Point{60, 10},
 			opts: []Option{
 				RedrawInterval(1),
 			},
@@ -195,30 +211,12 @@ func TestRun(t *testing.T) {
 				return ft
 			},
 		},
-		{
-			desc: "ignores input errors without error handler",
-			opts: []Option{
-				RedrawInterval(1),
-			},
-			events: []terminalapi.Event{
-				terminalapi.NewError("input error"),
-			},
-			want: func(size image.Point) *faketerm.Terminal {
-				ft := faketerm.MustNew(size)
-
-				fakewidget.MustDraw(
-					ft,
-					testcanvas.MustNew(ft.Area()),
-					widgetapi.Options{},
-				)
-				return ft
-			},
-		},
 		{
 			desc: "forwards input errors to the error handler",
+			size: image.Point{60, 10},
 			opts: []Option{
 				RedrawInterval(1),
-				InputErrorHandler(handler.handle),
+				ErrorHandler(handler.handle),
 			},
 			events: []terminalapi.Event{
 				terminalapi.NewError("input error"),
@@ -242,6 +240,7 @@ func TestRun(t *testing.T) {
 		},
 		{
 			desc: "forwards keyboard events to the subscriber",
+			size: image.Point{60, 10},
 			opts: []Option{
 				RedrawInterval(1),
 				KeyboardSubscriber(keySub.receive),
@@ -272,6 +271,7 @@ func TestRun(t *testing.T) {
 		},
 		{
 			desc: "forwards mouse events to the subscriber",
+			size: image.Point{60, 10},
 			opts: []Option{
 				RedrawInterval(1),
 				MouseSubscriber(mouseSub.receive),
@@ -313,7 +313,7 @@ func TestRun(t *testing.T) {
 				eq.Push(ev)
 			}
 
-			got, err := faketerm.New(image.Point{60, 10}, faketerm.WithEventQueue(eq))
+			got, err := faketerm.New(tc.size, faketerm.WithEventQueue(eq))
 			if err != nil {
 				t.Fatalf("faketerm.New => unexpected error: %v", err)
 			}