2 files changed, 131 insertions, 0 deletions
diff --git a/src/DotNetOpenAuth.Test/DotNetOpenAuth.Test.csproj b/src/DotNetOpenAuth.Test/DotNetOpenAuth.Test.csproj
index 3957cfa..1a7a406 100644
--- a/src/DotNetOpenAuth.Test/DotNetOpenAuth.Test.csproj
+++ b/src/DotNetOpenAuth.Test/DotNetOpenAuth.Test.csproj
@@ -128,6 +128,7 @@
     <Compile Include="Hosting\HttpHost.cs" />
     <Compile Include="Hosting\TestingWorkerRequest.cs" />
     <Compile Include="Messaging\CollectionAssert.cs" />
+    <Compile Include="Messaging\EnumerableCacheTests.cs" />
     <Compile Include="Messaging\ErrorUtilitiesTests.cs" />
     <Compile Include="Messaging\MessageSerializerTests.cs" />
     <Compile Include="Messaging\Reflection\MessageDescriptionTests.cs" />
diff --git a/src/DotNetOpenAuth.Test/Messaging/EnumerableCacheTests.cs b/src/DotNetOpenAuth.Test/Messaging/EnumerableCacheTests.cs
new file mode 100644
index 0000000..55f4394
--- /dev/null
+++ b/src/DotNetOpenAuth.Test/Messaging/EnumerableCacheTests.cs
@@ -0,0 +1,130 @@
+//-----------------------------------------------------------------------
+// <copyright file="EnumerableCacheTests.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+//     This code is released under the Microsoft Public License (Ms-PL).
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.Test.Messaging {
+	using System;
+	using System.Collections.Generic;
+	using System.Collections.ObjectModel;
+	using System.Linq;
+	using DotNetOpenAuth.Messaging;
+	using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+	/// <summary>
+	/// Tests for cached enumeration.
+	/// </summary>
+	[TestClass]
+	public class EnumerableCacheTests {
+		/// <summary>
+		/// The number of times the generator method's implementation is started.
+		/// </summary>
+		private int generatorInvocations;
+
+		/// <summary>
+		/// The number of times the end of the generator method's implementation is reached.
+		/// </summary>
+		private int generatorCompleted;
+
+		/// <summary>
+		/// Gets or sets the test context.
+		/// </summary>
+		public TestContext TestContext { get; set; }
+
+		/// <summary>
+		/// Sets up a test.
+		/// </summary>
+		[TestInitialize]
+		public void Setup() {
+			this.generatorInvocations = 0;
+			this.generatorCompleted = 0;
+		}
+
+		[TestMethod]
+		public void EnumerableCache() {
+			// Baseline
+			var generator = this.NumberGenerator();
+			var list1 = generator.ToList();
+			var list2 = generator.ToList();
+			Assert.AreEqual(2, this.generatorInvocations);
+			CollectionAssert.AreEqual(list1, list2);
+
+			// Cache behavior
+			this.generatorInvocations = 0;
+			this.generatorCompleted = 0;
+			generator = this.NumberGenerator().CacheGeneratedResults();
+			var list3 = generator.ToList();
+			var list4 = generator.ToList();
+			Assert.AreEqual(1, this.generatorInvocations);
+			Assert.AreEqual(1, this.generatorCompleted);
+			CollectionAssert.AreEqual(list1, list3);
+			CollectionAssert.AreEqual(list1, list4);
+		}
+
+		[TestMethod]
+		public void GeneratesOnlyRequiredElements() {
+			var generator = this.NumberGenerator().CacheGeneratedResults();
+			Assert.AreEqual(0, this.generatorInvocations);
+			generator.Take(2).ToList();
+			Assert.AreEqual(1, this.generatorInvocations);
+			Assert.AreEqual(0, this.generatorCompleted, "Only taking part of the list should not have completed the generator.");
+		}
+
+		[TestMethod]
+		public void PassThruDoubleCache() {
+			var cache1 = this.NumberGenerator().CacheGeneratedResults();
+			var cache2 = cache1.CacheGeneratedResults();
+			Assert.AreSame(cache1, cache2, "Two caches were set up rather than just sharing the first one.");
+		}
+
+		[TestMethod]
+		public void PassThruList() {
+			var list = this.NumberGenerator().ToList();
+			var cache = list.CacheGeneratedResults();
+			Assert.AreSame(list, cache);
+		}
+
+		[TestMethod]
+		public void PassThruArray() {
+			var array = this.NumberGenerator().ToArray();
+			var cache = array.CacheGeneratedResults();
+			Assert.AreSame(array, cache);
+		}
+
+		[TestMethod]
+		public void PassThruCollection() {
+			var collection = new Collection<int>();
+			var cache = collection.CacheGeneratedResults();
+			Assert.AreSame(collection, cache);
+		}
+
+		/// <summary>
+		/// Tests calling IEnumerator.Current before first call to MoveNext.
+		/// </summary>
+		[TestMethod, ExpectedException(typeof(InvalidOperationException))]
+		public void EnumerableCacheCurrentThrowsBefore() {
+			var foo = this.NumberGenerator().CacheGeneratedResults().GetEnumerator().Current;
+		}
+
+		/// <summary>
+		/// Tests calling IEnumerator.Current after MoveNext returns false.
+		/// </summary>
+		[TestMethod, ExpectedException(typeof(InvalidOperationException))]
+		public void EnumerableCacheCurrentThrowsAfter() {
+			var enumerator = this.NumberGenerator().CacheGeneratedResults().GetEnumerator();
+			while (enumerator.MoveNext()) {
+			}
+			var foo = enumerator.Current;
+		}
+
+		private IEnumerable<int> NumberGenerator() {
+			this.generatorInvocations++;
+			for (int i = 10; i < 15; i++) {
+				yield return i;
+			}
+			this.generatorCompleted++;
+		}
+	}
+}