ILSpy/ILSpy.Tests/Languages/CSharpILMixedLanguageTests.cs

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using System.Linq;
using System.Threading.Tasks;

using Avalonia.Headless.NUnit;

using AwesomeAssertions;

using ICSharpCode.Decompiler;
using ICSharpCode.ILSpy;
using ICSharpCode.ILSpy.AppEnv;
using ICSharpCode.ILSpy.Languages;
using ICSharpCode.ILSpy.TextView;
using ICSharpCode.ILSpy.TreeNodes;

using NUnit.Framework;

namespace ICSharpCode.ILSpy.Tests.Languages;

/// <summary>
/// The "IL with C#" language disassembles IL with the decompiled C# source interleaved as gray
/// comments. (Regression: the language was missing entirely from the Avalonia port.)
/// </summary>
[TestFixture]
public class CSharpILMixedLanguageTests
{
	[AvaloniaTest]
	public async Task ILWithCSharp_Is_Registered_And_Interleaves_CSharp_Into_The_IL()
	{
		var (_, vm) = await TestHarness.BootAsync(3);
		var languages = AppComposition.Current.GetExport<LanguageService>().Languages;

		var mixed = languages.FirstOrDefault(l => l.Name == "IL with C#");
		Assert.That(mixed, Is.Not.Null, "the 'IL with C#' language must be registered");
		var plainIL = languages.First(l => l.Name == "IL");

		var asm = vm.AssemblyTreeModel.FindNode<AssemblyTreeNode>("System.Linq");
		Assert.That(asm, Is.Not.Null);
		var typeSystem = asm!.LoadedAssembly.GetTypeSystemOrNull();
		Assert.That(typeSystem, Is.Not.Null);
		var type = typeSystem!.MainModule.TypeDefinitions.First(t => t.FullName == "System.Linq.Enumerable");
		var method = type.Methods.First(m => m.HasBody);

		string Decompile(Language language)
		{
			var output = new AvaloniaEditTextOutput();
			language.DecompileMethod(method, output, new DecompilationOptions(new DecompilerSettings()));
			return output.GetText();
		}

		var mixedText = Decompile(mixed!);
		var ilText = Decompile(plainIL);

		mixedText.Should().Contain("//", "the decompiled C# is interleaved as comments");
		mixedText.Length.Should().BeGreaterThan(ilText.Length,
			"the interleaved C# source makes the mixed output longer than plain IL");
	}
}