Allow CollectionAttribute to reference a definition class directly (#…

…2878)

src/common.tests/TestDoubles/Mocks.Attributes.cs

@@ -50,6 +50,27 @@ public static _IReflectionAttributeInfo CollectionAttribute(string collectionNam
 		return result;
 	}
 
+	public static _IReflectionAttributeInfo CollectionAttribute(Type collectionType)
+	{
+		var result = Substitute.For<_IReflectionAttributeInfo, InterfaceProxy<_IReflectionAttributeInfo>>();
+		result.Attribute.Returns(new CollectionAttribute(collectionType));
+		result.AttributeType.Returns(Reflector.Wrap(typeof(CollectionAttribute)));
+		result.GetConstructorArguments().Returns(new[] { collectionType });
+		return result;
+	}
+
+#if !NETFRAMEWORK
+
+	public static _IReflectionAttributeInfo CollectionAttribute<TCollectionType>()
+	{
+		var result = Substitute.For<_IReflectionAttributeInfo, InterfaceProxy<_IReflectionAttributeInfo>>();
+		result.Attribute.Returns(new CollectionAttribute<TCollectionType>());
+		result.AttributeType.Returns(Reflector.Wrap(typeof(CollectionAttribute<TCollectionType>)));
+		return result;
+	}
+
+#endif
+
 	public static _IReflectionAttributeInfo CollectionBehaviorAttribute(
 		CollectionBehavior? collectionBehavior = null,
 		bool disableTestParallelization = false,

src/xunit.v3.common/Utility/UniqueIDGenerator.cs

@@ -223,6 +223,23 @@ public void Dispose()
 		return generator.Compute();
 	}
 
+	/// <summary>
+	/// Computes a unique ID for a type/>
+	/// </summary>
+	/// <param name="type">The type to generate an ID for</param>
+	public static string ForType(_ITypeInfo type)
+	{
+		Guard.ArgumentNotNull(type);
+
+		using var generator = new UniqueIDGenerator();
+
+		// Assembly name may include some parts that are less stable, so for now, split on comma
+		var assemblyParts = type.Assembly.Name.Split(',');
+		generator.Add(assemblyParts[0]);
+		generator.Add(type.Name);
+		return generator.Compute();
+	}
+
 	static char ToHexChar(int b) =>
 		(char)(b < 10 ? b + '0' : b - 10 + 'a');