ILSpy/ILSpy.Tests/Editor/XmlDocumentationTests.cs

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using AwesomeAssertions;

using ICSharpCode.Decompiler.Documentation;

using ICSharpCode.ILSpyX;

using NUnit.Framework;

namespace ICSharpCode.ILSpy.Tests.TextView;

/// <summary>
/// The XML-documentation lookup behind the decompiler view's hover tooltip. On modern .NET
/// the entity's metadata-token-bearing assembly (System.Private.CoreLib.dll) is not the one
/// whose XML carries its docs (System.Runtime.xml), so <see cref="XmlDocLoader"/> falls back
/// to the parallel ref pack - <c>&lt;dotnet&gt;/packs/Microsoft.NETCore.App.Ref/&lt;version&gt;/ref/&lt;tfm&gt;/*.xml</c>
/// - and aggregates every XML there into one provider. Without that fallback every tooltip
/// over a BCL member renders empty.
/// </summary>
[TestFixture]
public class XmlDocumentationTests
{
	// The ID string the decompiler produces for the two-argument overload; using the literal
	// keeps the test off the type system, which is not what is under test here.
	const string StringConcatId = "M:System.String.Concat(System.String,System.String)";

	[Test]
	public void XmlDocLoader_Surfaces_Documentation_For_CoreLib_String_Concat()
	{
		var coreLib = new AssemblyList().OpenAssembly(typeof(object).Assembly.Location)
			.GetMetadataFileOrNull();
		coreLib.Should().NotBeNull();

		var provider = XmlDocLoader.LoadDocumentation(coreLib!);
		((object?)provider).Should().NotBeNull(
			"the ref-pack fallback must locate the XMLs for the test-host runtime layout");

		var documentation = provider!.GetDocumentation(StringConcatId);

		documentation.Should().NotBeNullOrEmpty(
			"System.String.Concat is one of the most-documented methods in CoreLib - the hover "
			+ "tooltip would be empty without this");
		documentation.Should().Contain("<summary",
			"the raw documentation string must include the <summary> tag the renderer parses");
	}
}