MonoGame.Extended/Source/Tests/MonoGame.Extended.Gui.Tests/Controls/GuiButtonTests.cs

using System.Collections.Generic;
using Microsoft.Xna.Framework.Graphics;
using MonoGame.Extended.BitmapFonts;
using MonoGame.Extended.Gui.Controls;
using MonoGame.Extended.Tests;
using MonoGame.Extended.TextureAtlases;
using NSubstitute;
using NUnit.Framework;

namespace MonoGame.Extended.Gui.Tests.Controls
{
    [TestFixture]
    public class GuiButtonTests
    {
        [Test]
        public void DesiredSizeShouldBeEmptyByDefault()
        {
            var availableSize = new Size2(800, 480);
            var context = Substitute.For<IGuiContext>();
            var button = new GuiButton();
            var desiredSize = button.GetDesiredSize(context, availableSize);

            Assert.That(desiredSize, Is.EqualTo(Size2.Empty));
        }

        [Test]
        public void DesiredSizeShouldBeTheSizeOfTheBackgroundRegion()
        {
            var availableSize = new Size2(800, 480);
            var context = Substitute.For<IGuiContext>();
            var backgroundRegion = MockTextureRegion();
            var button = new GuiButton(backgroundRegion);
            var desiredSize = button.GetDesiredSize(context, availableSize);

            Assert.That(desiredSize, Is.EqualTo(backgroundRegion.Size));
        }

        [Test]
        public void DesiredSizeShouldBeTheSizeOfTheMarginsInANinePatchRegion()
        {
            var availableSize = new Size2(800, 480);
            var context = Substitute.For<IGuiContext>();
            var texture = new Texture2D(new TestGraphicsDevice(), 512, 512);
            var backgroundRegion = new NinePatchRegion2D(new TextureRegion2D(texture), new Thickness(10, 20));
            var button = new GuiButton(backgroundRegion);
            var desiredSize = button.GetDesiredSize(context, availableSize);

            Assert.That(desiredSize, Is.EqualTo(new Size2(20, 40)));
        }

        [Test]
        public void DesiredSizeShouldAtLeastBeTheSizeOfTheText()
        {
            const string text = "abc";

            var availableSize = new Size2(800, 480);
            var context = Substitute.For<IGuiContext>();
            var font = CreateMockFont(text, lineHeight: 32);
            var expectedSize = font.MeasureString(text);
            var button = new GuiButton {Text = text, Font = font};

            var desiredSize = button.GetDesiredSize(context, availableSize);

            Assert.That(desiredSize, Is.EqualTo(expectedSize));
        }

        private static BitmapFont CreateMockFont(string text, int lineHeight)
        {
            var regions = new List<BitmapFontRegion>();
            var xOffset = 0;

            foreach (var character in text)
            {
                regions.Add(new BitmapFontRegion(MockTextureRegion(10, 10), character, xOffset, yOffset: 0, xAdvance: 0));
                xOffset += 10;
            }

            return new BitmapFont("font", regions, lineHeight);
        }

        private static TextureRegion2D MockTextureRegion(int width = 100, int height = 200)
        {
            var texture = new Texture2D(new TestGraphicsDevice(), width, height);
            return new TextureRegion2D(texture, 0, 0, width, height);
        }
    }
}