Moved all unit test files into a separate directory in preparation for splitting the project

Tests/SharedTest.cs

@@ -0,0 +1,68 @@
+#region Apache License 2.0
+/*
+Nuclex .NET Framework
+Copyright (C) 2002-2024 Markus Ewald / Nuclex Development Labs
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+#endregion // Apache License 2.0
+
+using System;
+using System.IO;
+
+#if UNITTEST
+
+using NUnit.Framework;
+
+namespace Nuclex.Support {
+
+  /// <summary>Unit Test for the shared instance provider class</summary>
+  [TestFixture]
+  internal class SharedTest {
+
+    #region class Dummy
+
+    /// <summary>Dummy class for testing the shared instance provider</summary>
+    private class Dummy {
+      /// <summary>Initializes a new dummy</summary>
+      public Dummy() {}
+    }
+
+    #endregion // class Dummy
+
+    /// <summary>
+    ///   Verifies that the shared instance provider returns the same instance of a class
+    ///   when asked for the same class twice.
+    /// </summary>
+    [Test]
+    public void TestSameInstance() {
+      #pragma warning disable 0618
+      Dummy dummyInstance = Shared<Dummy>.Instance;
+      Dummy otherDummyInstance = Shared<Dummy>.Instance;
+      #pragma warning restore 0618
+      
+      // Make sure they're the same instance. We could have put an instance counter in
+      // the dummy class, but this might or might not work well across multiple tests
+      // because the order in which tests are executed is undefined and Shared<> changes
+      // its global state when the first test is run by remembering the instance.
+      //
+      // Maybe this really is a defect in Shared<> and the class should be equipped with
+      // a method such as Discard() or Dispose() to get rid of the instance?
+      Assert.AreSame(dummyInstance, otherDummyInstance);
+    }
+
+  }
+
+} // namespace Nuclex.Support
+
+#endif // UNITTEST