XmlnsCollision.xaml.cs

using Microsoft.Maui.ApplicationModel;
using Microsoft.Maui.Controls;
using Microsoft.Maui.Controls.Build.Tasks;
using Microsoft.Maui.Controls.Core.UnitTests;
using NUnit.Framework;

[assembly: XmlnsDefinition("http://companyone.com/schemas/toolkit", "CompanyOne.Controls")]
[assembly: XmlnsPrefix("http://companyone.com/schemas/toolkit", "c1")]
[assembly: XmlnsDefinition("http://companytwo.com/schemas/toolkit", "CompanyTwo.Controls")]
[assembly: XmlnsPrefix("http://companytwo.com/schemas/toolkit", "c2")]
[assembly: XmlnsDefinition("http://schemas.microsoft.com/dotnet/maui/global", "http://companyone.com/schemas/toolkit")]
[assembly: XmlnsDefinition("http://schemas.microsoft.com/dotnet/maui/global", "http://companytwo.com/schemas/toolkit")]

namespace CompanyOne.Controls
{
	public class ConflictingLabel : Label
	{
	}
}

namespace CompanyTwo.Controls
{
	public class ConflictingLabel : Label
	{
	}
}

namespace Microsoft.Maui.Controls.Xaml.UnitTests
{
	[XamlCompilation(XamlCompilationOptions.Skip)]
	public partial class XmlnsCollision : ContentPage
	{
		public XmlnsCollision()
		{
			InitializeComponent();
		}
		public XmlnsCollision(bool useCompiledXaml)
		{
			//this stub will be replaced at compile time
		}

		[TestFixture]
		class Test
		{
			[SetUp] public void Setup() => AppInfo.SetCurrent(new MockAppInfo());
			[TearDown] public void TearDown() => AppInfo.SetCurrent(null);

			[Test]
			public void ConflictInXmlns([Values] bool useCompiledXaml)
			{
				if (useCompiledXaml)
					Assert.Throws<BuildException>(() =>
					{
						MockCompiler.Compile(typeof(XmlnsCollision), out var hasLoggedErrors);
						Assert.IsTrue(hasLoggedErrors);
					});

				else
					Assert.Throws<XamlParseException>(() =>
					{
						var layout = new XmlnsCollision(useCompiledXaml);
					});
			}
		}
	}
}