fix focus next/previous bug

With the move of focus next/previous to FocusManager the action
lost the ability to notify the Focusable.
This commit restores it and adds appropriate tests.

internal/app/focus.go

@@ -24,22 +24,7 @@ func NewFocusManager(c fyne.CanvasObject) *FocusManager {
 func (f *FocusManager) Focus(obj fyne.Focusable) {
 	f.Lock()
 	defer f.Unlock()
-
-	if f.focused == obj {
-		return
-	}
-
-	if dis, ok := obj.(fyne.Disableable); ok && dis.Disabled() {
-		obj = nil
-	}
-
-	if f.focused != nil {
-		f.focused.FocusLost()
-	}
-	f.focused = obj
-	if obj != nil {
-		obj.FocusGained()
-	}
+	f.focus(obj)
 }
 
 // Focused returns the currently focused object or nil if none.
@@ -54,15 +39,33 @@ func (f *FocusManager) Focused() fyne.Focusable {
 func (f *FocusManager) FocusNext() {
 	f.Lock()
 	defer f.Unlock()
-	f.focused = f.nextInChain(f.focused)
+	f.focus(f.nextInChain(f.focused))
 }
 
 // FocusPrevious will find the item before the current that can be focused and focus it.
 // If current is nil then the last focusable item in the canvas will be focused.
 func (f *FocusManager) FocusPrevious() {
 	f.Lock()
 	defer f.Unlock()
-	f.focused = f.previousInChain(f.focused)
+	f.focus(f.previousInChain(f.focused))
+}
+
+func (f *FocusManager) focus(obj fyne.Focusable) {
+	if f.focused == obj {
+		return
+	}
+
+	if dis, ok := obj.(fyne.Disableable); ok && dis.Disabled() {
+		obj = nil
+	}
+
+	if f.focused != nil {
+		f.focused.FocusLost()
+	}
+	f.focused = obj
+	if obj != nil {
+		obj.FocusGained()
+	}
 }
 
 func (f *FocusManager) nextInChain(current fyne.Focusable) fyne.Focusable {

internal/app/focus_test.go

@@ -10,79 +10,115 @@ import (
 )
 
 func TestFocusManager_Focus(t *testing.T) {
-	entry1 := widget.NewEntry()
+	entry1 := &focusable{}
 	hidden := widget.NewCheck("test", func(bool) {})
 	hidden.Hide()
-	entry2 := widget.NewEntry()
+	entry2 := &focusable{}
 	disabled := widget.NewCheck("test", func(bool) {})
 	disabled.Disable()
-	entry3 := widget.NewEntry()
+	entry3 := &focusable{}
 	c := widget.NewVBox(entry1, hidden, entry2, disabled, entry3)
 
 	manager := app.NewFocusManager(c)
 	assert.Nil(t, manager.Focused())
 
 	manager.Focus(entry2)
 	assert.Equal(t, entry2, manager.Focused())
+	assert.True(t, entry2.focused)
 
 	manager.Focus(entry1)
 	assert.Equal(t, entry1, manager.Focused())
+	assert.True(t, entry1.focused)
+	assert.False(t, entry2.focused)
 
 	manager.Focus(entry3)
 	assert.Equal(t, entry3, manager.Focused())
+	assert.True(t, entry3.focused)
+	assert.False(t, entry1.focused)
 
 	manager.Focus(nil)
 	assert.Nil(t, manager.Focused())
+	assert.False(t, entry3.focused)
 }
 
 func TestFocusManager_FocusNext(t *testing.T) {
-	entry1 := widget.NewEntry()
+	entry1 := &focusable{}
 	hidden := widget.NewCheck("test", func(bool) {})
 	hidden.Hide()
-	entry2 := widget.NewEntry()
+	entry2 := &focusable{}
 	disabled := widget.NewCheck("test", func(bool) {})
 	disabled.Disable()
-	entry3 := widget.NewEntry()
+	entry3 := &focusable{}
 	c := widget.NewVBox(entry1, hidden, entry2, disabled, entry3)
 
 	manager := app.NewFocusManager(c)
 	assert.Nil(t, manager.Focused())
 
 	manager.FocusNext()
 	assert.Equal(t, entry1, manager.Focused())
+	assert.True(t, entry1.focused)
 
 	manager.FocusNext()
 	assert.Equal(t, entry2, manager.Focused())
+	assert.True(t, entry2.focused)
+	assert.False(t, entry1.focused)
 
 	manager.FocusNext()
 	assert.Equal(t, entry3, manager.Focused())
+	assert.True(t, entry3.focused)
+	assert.False(t, entry2.focused)
 
 	manager.FocusNext()
 	assert.Equal(t, entry1, manager.Focused())
+	assert.True(t, entry1.focused)
+	assert.False(t, entry3.focused)
 }
 
 func TestFocusManager_FocusPrevious(t *testing.T) {
-	entry1 := widget.NewEntry()
+	entry1 := &focusable{}
 	hidden := widget.NewCheck("test", func(bool) {})
 	hidden.Hide()
-	entry2 := widget.NewEntry()
+	entry2 := &focusable{}
 	disabled := widget.NewCheck("test", func(bool) {})
 	disabled.Disable()
-	entry3 := widget.NewEntry()
+	entry3 := &focusable{}
 	c := widget.NewVBox(entry1, hidden, entry2, disabled, entry3)
 
 	manager := app.NewFocusManager(c)
 	assert.Nil(t, manager.Focused())
 
 	manager.FocusPrevious()
 	assert.Equal(t, entry3, manager.Focused())
+	assert.True(t, entry3.focused)
 
 	manager.FocusPrevious()
 	assert.Equal(t, entry2, manager.Focused())
+	assert.True(t, entry2.focused)
+	assert.False(t, entry3.focused)
 
 	manager.FocusPrevious()
 	assert.Equal(t, entry1, manager.Focused())
+	assert.True(t, entry1.focused)
+	assert.False(t, entry2.focused)
 
 	manager.FocusPrevious()
 	assert.Equal(t, entry3, manager.Focused())
+	assert.True(t, entry3.focused)
+	assert.False(t, entry1.focused)
+}
+
+type focusable struct {
+	widget.Entry
+	focused bool
+}
+
+func (f *focusable) FocusGained() {
+	if f.Disabled() {
+		return
+	}
+	f.focused = true
+}
+
+func (f *focusable) FocusLost() {
+	f.focused = false
 }