public void When_Margin_Default()
        {
            var element        = new PlainFrameworkElement();
            var actualMargin   = element.FocusVisualMargin;
            var expectedMargin = ThicknessFromUniformLength(0);

            Assert.AreEqual(expectedMargin, actualMargin);
        }
        public void When_SecondaryBrush_Default()
        {
            var element       = new PlainFrameworkElement();
            var expectedBrush = Application.Current.Resources["SystemControlFocusVisualSecondaryBrush"];
            var actualBrush   = element.FocusVisualSecondaryBrush;

            Assert.AreEqual(expectedBrush, actualBrush);
        }
        public void When_SecondaryThickness_Default()
        {
            var element           = new PlainFrameworkElement();
            var actualThickness   = element.FocusVisualSecondaryThickness;
            var expectedThickness = ThicknessFromUniformLength(1);

            Assert.AreEqual(expectedThickness, actualThickness);
        }