Add the scenario tests for the skiasharp backend

src/Graphics/tests/Graphics.Tests/.gitignore

@@ -0,0 +1 @@
+Errors/

src/Graphics/tests/Graphics.Tests/Graphics.Tests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
 	<PropertyGroup>
 		<TargetFramework>$(_MauiDotNetTfm)</TargetFramework>
@@ -10,15 +10,35 @@
 	</ItemGroup>
 
 	<ItemGroup>
-		<PackageReference Include="xunit" Version="$(XunitPackageVersion)"/>
-		<PackageReference Include="coverlet.collector" Version="$(CoverletCollectorPackageVersion)" >
+		<PackageReference Include="xunit" Version="$(XunitPackageVersion)" />
+		<PackageReference Include="coverlet.collector" Version="$(CoverletCollectorPackageVersion)">
 			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
 			<PrivateAssets>all</PrivateAssets>
 		</PackageReference>
+    <PackageReference Include="SkiaSharp" />
+    <PackageReference Include="SkiaSharp.Extended" />
 	</ItemGroup>
 
 	<ItemGroup>
+		<ProjectReference Include="..\..\samples\GraphicsTester.Portable\GraphicsTester.Portable.csproj" />
+		<ProjectReference Include="..\..\src\Graphics.Skia\Graphics.Skia.csproj" />
 		<ProjectReference Include="..\..\src\Graphics\Graphics.csproj" />
 	</ItemGroup>
 
+  <ItemGroup>
+    <EmbeddedResource Include="..\..\samples\GraphicsTester.Portable\Resources\**" Link="Resources\%(RecursiveDir)%(Filename)%(Extension)" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <None Include="TestImages\**" />
+    <None Update="TestImages\Windows\**" CopyToOutputDirectory="PreserveNewest" Condition="$([MSBuild]::IsOSPlatform('windows'))" />
+    <None Update="TestImages\Mac\**" CopyToOutputDirectory="PreserveNewest" Condition="$([MSBuild]::IsOSPlatform('osx'))" />
+    <None Update="TestImages\Linux\**" CopyToOutputDirectory="PreserveNewest" Condition="!$([MSBuild]::IsOSPlatform('windows')) and !$([MSBuild]::IsOSPlatform('osx'))" />
+    <None Include="Errors\**" CopyToOutputDirectory="Never" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Folder Include="Errors\" />
+  </ItemGroup>
+
 </Project>

src/Graphics/tests/Graphics.Tests/ImageAssert.cs

@@ -0,0 +1,59 @@
+using System.IO;
+using SkiaSharp;
+using SkiaSharp.Extended;
+using Xunit;
+
+namespace Microsoft.Maui;
+
+public static class ImageAssert
+{
+	private const double ImageErrorThreshold = 0.0027;
+
+	public static void Equivalent(Stream actualData, string expectedFilename, string diffDirectory, double threshold = ImageErrorThreshold)
+	{
+		using var actual = SKImage.FromEncodedData(actualData);
+		Equivalent(actual, expectedFilename, diffDirectory, threshold);
+	}
+
+	public static void Equivalent(string actualFilename, string expectedFilename, string diffDirectory, double threshold = ImageErrorThreshold)
+	{
+		using var actual = SKImage.FromEncodedData(actualFilename);
+		Equivalent(actual, expectedFilename, diffDirectory, threshold);
+	}
+
+	public static void Equivalent(SKImage actual, string expectedFilename, string diffDirectory, double threshold = ImageErrorThreshold)
+	{
+		var expected = SKImage.FromEncodedData(expectedFilename);
+		var similarity = SKPixelComparer.Compare(actual, expected);
+
+		var isSimilar = similarity.ErrorPixelPercentage <= threshold;
+
+		if (isSimilar)
+		{
+			return;
+		}
+
+		var outputFilename = Path.Combine(diffDirectory, expectedFilename);
+
+		var diffFilename = Path.ChangeExtension(outputFilename, ".diff.png");
+
+		Directory.CreateDirectory(Path.GetDirectoryName(diffFilename));
+
+		using (var diff = SKPixelComparer.GenerateDifferenceMask(actual, expected))
+		using (var diffData = diff.Encode(SKEncodedImageFormat.Png, 100))
+		using (var diffFile = File.Create(diffFilename))
+		{
+			diffData.SaveTo(diffFile);
+		}
+
+		using (var actualData = actual.Encode(SKEncodedImageFormat.Png, 100))
+		using (var actualFile = File.Create(Path.ChangeExtension(outputFilename, ".png")))
+		{
+			actualData.SaveTo(actualFile);
+		}
+
+		File.Copy(expectedFilename, Path.ChangeExtension(outputFilename, ".expected.png"), true);
+
+		Assert.Fail($"Image was not equal. Error was {similarity.ErrorPixelPercentage}% ({similarity.AbsoluteError} pixels). See {diffFilename}");
+	}
+}

src/Graphics/tests/Graphics.Tests/SkiaSharpScenarioTests.cs

@@ -0,0 +1,97 @@
+using System;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices;
+using GraphicsTester.Scenarios;
+using Microsoft.Maui.Graphics.Skia;
+using Xunit;
+
+namespace Microsoft.Maui.Graphics.Tests;
+
+public class SkiaSharpScenarioTests
+{
+	public static TheoryData<string> Scenarios =>
+		new(ScenarioList.Scenarios.Select(s => s.ToString()));
+
+	[Theory]
+	[MemberData(nameof(Scenarios))]
+	public void Scenario(string scenarioName)
+	{
+		// find scenario
+		var scenario = ScenarioList.Scenarios.Single(s => s.ToString() == scenarioName);
+
+		// render scenario
+		using var bmp = new SkiaBitmapExportContext((int)scenario.Width, (int)scenario.Height, 1f);
+		bmp.Canvas.FillColor = Colors.Transparent;
+		bmp.Canvas.FillRectangle(0, 0, scenario.Width, scenario.Height);
+		scenario.Draw(bmp.Canvas);
+
+		var expectedImagePath = GetExpectedImageaPath(scenario);
+
+		// save image if it did not exist, then fail the test
+		if (!File.Exists(expectedImagePath))
+		{
+			var newImageFilename = Path.Combine(ProjectRoot, expectedImagePath);
+			Directory.CreateDirectory(Path.GetDirectoryName(newImageFilename));
+
+			bmp.WriteToFile(newImageFilename);
+
+			Assert.Fail($"Image file did not exist, created: {newImageFilename}");
+		}
+
+		// file existed, compare
+		ImageAssert.Equivalent(bmp.SKImage, expectedImagePath, GetErrorsImageDirectory(), 0);
+	}
+
+	private static string ProjectRoot =>
+		Path.GetFullPath("../../../../../src/Graphics/tests/Graphics.Tests");
+
+	private static string GetExpectedImageaPath(AbstractScenario scenario)
+	{
+		var fileName = GetSafeFilename(scenario.ToString()) + ".png";
+		var os = RuntimeInformation.IsOSPlatform(OSPlatform.Windows)
+			? "Windows"
+			: RuntimeInformation.IsOSPlatform(OSPlatform.OSX)
+				? "Mac"
+				: "Linux";
+		var filePath = Path.Combine("TestImages", os, fileName);
+
+		return filePath;
+	}
+
+	private static string GetErrorsImageDirectory()
+	{
+		var outputFolder = Path.GetFullPath(Path.Combine(ProjectRoot, "Errors"));
+
+		if (Environment.GetEnvironmentVariable("BUILD_ARTIFACTSTAGINGDIRECTORY") is { } asd && !string.IsNullOrWhiteSpace(asd))
+		{
+			outputFolder = Path.GetFullPath(Path.Combine(
+				asd, typeof(SkiaSharpScenarioTests).FullName, "Errors"));
+		}
+
+		Directory.CreateDirectory(outputFolder);
+
+		return outputFolder;
+	}
+
+	private static string GetSafeFilename(string text)
+	{
+		char[] chars = text.ToCharArray();
+
+		char[] allowedSpecialChars = ['_', '-'];
+		for (int i = 0; i < chars.Length; i++)
+		{
+			chars[i] = char.IsLetterOrDigit(chars[i]) || allowedSpecialChars.Contains(chars[i])
+				? char.ToLowerInvariant(chars[i])
+				: '-';
+		}
+
+		var safe = new string(chars);
+		while (safe.Contains("--", StringComparison.OrdinalIgnoreCase))
+		{
+			safe = safe.Replace("--", "-", StringComparison.OrdinalIgnoreCase);
+		}
+
+		return safe.Trim('-');
+	}
+}

src/SingleProject/Resizetizer/test/UnitTests/.gitignore

@@ -0,0 +1 @@
+errors/

src/SingleProject/Resizetizer/test/UnitTests/BaseTest.cs

@@ -6,6 +6,7 @@
 using SkiaSharp;
 using SkiaSharp.Extended;
 using Xunit;
+using Xunit.Abstractions;
 
 namespace Microsoft.Maui.Resizetizer.Tests
 {
@@ -18,28 +19,28 @@ public class BaseTest : IDisposable
 		private readonly string DeleteDirectory;
 		protected readonly string DestinationDirectory;
 
-		public BaseTest(string testContextDirectory = null)
+		public BaseTest(ITestOutputHelper output)
 		{
-			if (!string.IsNullOrEmpty(testContextDirectory))
-			{
-				DestinationDirectory = testContextDirectory;
-				DeleteDirectory = testContextDirectory;
-			}
-			else
-			{
-				var name = GetType().FullName;
-				if (name.StartsWith(TestFolderName + ".", StringComparison.OrdinalIgnoreCase))
-					name = name.Substring(TestFolderName.Length + 1);
+			Output = output;
 
-				var dir = Path.Combine(Path.GetTempPath(), TestFolderName, name, Path.GetRandomFileName());
+			var name = GetType().FullName;
+			if (name.StartsWith(TestFolderName + ".", StringComparison.OrdinalIgnoreCase))
+				name = name.Substring(TestFolderName.Length + 1);
 
-				DestinationDirectory = dir;
-				DeleteDirectory = dir;
-			}
+			var dir = Path.Combine(Path.GetTempPath(), TestFolderName, name, Path.GetRandomFileName());
+
+			DestinationDirectory = dir;
+			DeleteDirectory = dir;
+
+			Output.WriteLine($"Using DestinationDirectory={DestinationDirectory}");
 		}
 
+		public ITestOutputHelper Output { get; }
+
 		public virtual void Dispose()
 		{
+			Output.WriteLine($"Cleaning up directories={DeleteDirectory}");
+
 			if (Directory.Exists(DeleteDirectory))
 				Directory.Delete(DeleteDirectory, true);
 		}
@@ -137,33 +138,12 @@ void AssertFileMatchesReal(string actualFilename, object[] args = null, [CallerM
 			}
 			else
 			{
-				using var actual = SKImage.FromEncodedData(actualFilename);
-				using var expected = SKImage.FromEncodedData(expectedFilename);
-
-				var similarity = SKPixelComparer.Compare(actual, expected);
-
-				var isSimilar = similarity.ErrorPixelPercentage <= ImageErrorThreshold;
-
-				if (!isSimilar)
-				{
-					var root = GetTestProjectRoot();
-
-					var maskFilename = Path.Combine(root, "errors", expectedFilename);
-					maskFilename = Path.ChangeExtension(maskFilename, ".mask.png");
-
-					Directory.CreateDirectory(Path.GetDirectoryName(maskFilename));
+				var root = GetTestProjectRoot();
+				var diffDir = Path.Combine(root, "errors");
 
-					using (var mask = SKPixelComparer.GenerateDifferenceMask(actual, expected))
-					using (var data = mask.Encode(SKEncodedImageFormat.Png, 100))
-					using (var maskFile = File.Create(maskFilename))
-					{
-						data.SaveTo(maskFile);
-					}
+				Output.WriteLine($"Validating image similarity with diff dir:{diffDir}");
 
-					Assert.True(
-						isSimilar,
-						$"Image was not equal. Error was {similarity.ErrorPixelPercentage}% ({similarity.AbsoluteError} pixels). See {maskFilename}");
-				}
+				ImageAssert.Equivalent(actualFilename, expectedFilename, diffDir);
 			}
 		}
 

src/SingleProject/Resizetizer/test/UnitTests/DetectInvalidResourceOutputFilenamesTests.cs

@@ -7,13 +7,19 @@
 using Microsoft.Build.Utilities;
 using SkiaSharp;
 using Xunit;
+using Xunit.Abstractions;
 
 namespace Microsoft.Maui.Resizetizer.Tests
 {
 	public class DetectInvalidResourceOutputFilenamesTests
 	{
 		public class ExecuteForApp : MSBuildTaskTestFixture<DetectInvalidResourceOutputFilenamesTask>
 		{
+			public ExecuteForApp(ITestOutputHelper output)
+				: base(output)
+			{
+			}
+
 			protected DetectInvalidResourceOutputFilenamesTask GetNewTask(params ITaskItem[] items) =>
 				new DetectInvalidResourceOutputFilenamesTask
 				{

src/SingleProject/Resizetizer/test/UnitTests/GeneratePackageAppxManifestTests.cs

@@ -5,11 +5,17 @@
 using Microsoft.Build.Framework;
 using Microsoft.Build.Utilities;
 using Xunit;
+using Xunit.Abstractions;
 
 namespace Microsoft.Maui.Resizetizer.Tests
 {
 	public class GeneratePackageAppxManifestTests : MSBuildTaskTestFixture<GeneratePackageAppxManifest>
 	{
+		public GeneratePackageAppxManifestTests(ITestOutputHelper output)
+			: base(output)
+		{
+		}
+
 		protected GeneratePackageAppxManifest GetNewTask(
 			string manifest,
 			string? generatedFilename = null,

src/SingleProject/Resizetizer/test/UnitTests/GenerateSplashAndroidResourcesTests.cs

@@ -6,6 +6,7 @@
 using Microsoft.Build.Framework;
 using Microsoft.Build.Utilities;
 using Xunit;
+using Xunit.Abstractions;
 
 namespace Microsoft.Maui.Resizetizer.Tests
 {
@@ -17,7 +18,8 @@ public class GenerateSplashAndroidResourcesTests : MSBuildTaskTestFixture<Genera
 
 		static readonly Dictionary<string, string> ResizeMetadata = new() { ["Resize"] = "true" };
 
-		public GenerateSplashAndroidResourcesTests()
+		public GenerateSplashAndroidResourcesTests(ITestOutputHelper outputHelper)
+			: base(outputHelper)
 		{
 			_colors = Path.Combine(DestinationDirectory, "values", "maui_colors.xml");
 			_drawable = Path.Combine(DestinationDirectory, "drawable", "maui_splash_image.xml");

src/SingleProject/Resizetizer/test/UnitTests/GenerateSplashAssetsTests.cs

@@ -5,11 +5,17 @@
 using Microsoft.Build.Utilities;
 using SkiaSharp;
 using Xunit;
+using Xunit.Abstractions;
 
 namespace Microsoft.Maui.Resizetizer.Tests
 {
 	public class GenerateSplashAssetsTests : MSBuildTaskTestFixture<GenerateSplashAssets>
 	{
+		public GenerateSplashAssetsTests(ITestOutputHelper output)
+			: base(output)
+		{
+		}
+
 		protected GenerateSplashAssets GetNewTask(ITaskItem splash) =>
 			new()
 			{

src/SingleProject/Resizetizer/test/UnitTests/GenerateSplashStoryboardTests.cs

@@ -6,6 +6,7 @@
 using Microsoft.Build.Utilities;
 using SkiaSharp;
 using Xunit;
+using Xunit.Abstractions;
 
 namespace Microsoft.Maui.Resizetizer.Tests
 {
@@ -15,7 +16,8 @@ public class GenerateSplashStoryboardTests : MSBuildTaskTestFixture<GenerateSpla
 
 		readonly string _storyboard;
 
-		public GenerateSplashStoryboardTests()
+		public GenerateSplashStoryboardTests(ITestOutputHelper outputHelper)
+			: base(outputHelper)
 		{
 			_storyboard = Path.Combine(DestinationDirectory, "MauiSplash.storyboard");
 		}