Testing and related fixes
diff --git a/src/ProtocolBuffersLite.Test/ExtendableBuilderLiteTest.cs b/src/ProtocolBuffersLite.Test/ExtendableBuilderLiteTest.cs
new file mode 100644
index 0000000..0a75559
--- /dev/null
+++ b/src/ProtocolBuffersLite.Test/ExtendableBuilderLiteTest.cs
@@ -0,0 +1,225 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://github.com/jskeet/dotnet-protobufs/
+// Original C++/Java/Python code:
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using Google.ProtocolBuffers;
+using Google.ProtocolBuffers.TestProtos;
+using NUnit.Framework;
+
+namespace Google.ProtocolBuffers {
+  [TestFixture]
+  public class ExtendableBuilderLiteTest {
+
+    [Test]
+    public void TestHasExtensionT() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder()
+          .SetExtension(UnitTestLiteProtoFile.OptionalInt32ExtensionLite, 123);
+
+      Assert.IsTrue(builder.HasExtension(UnitTestLiteProtoFile.OptionalInt32ExtensionLite));
+    }
+
+    [Test]
+    public void TestHasExtensionTMissing() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder();
+      Assert.IsFalse(builder.HasExtension(UnitTestLiteProtoFile.OptionalInt32ExtensionLite));
+    }
+
+    [Test]
+    public void TestGetExtensionCountT() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder()
+          .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 1)
+          .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 2)
+          .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 3);
+
+      Assert.AreEqual(3, builder.GetExtensionCount(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite));
+    }
+
+    [Test]
+    public void TestGetExtensionCountTEmpty() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder();
+      Assert.AreEqual(0, builder.GetExtensionCount(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite));
+    }
+
+    [Test]
+    public void TestGetExtensionTNull() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder();
+      string value = builder.GetExtension(UnitTestLiteProtoFile.OptionalStringExtensionLite);
+      Assert.IsNull(value);
+    }
+
+    [Test]
+    public void TestGetExtensionTValue() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder()
+          .SetExtension(UnitTestLiteProtoFile.OptionalInt32ExtensionLite, 3);
+
+      Assert.AreEqual(3, builder.GetExtension(UnitTestLiteProtoFile.OptionalInt32ExtensionLite));
+    }
+
+    [Test]
+    public void TestGetExtensionTEmpty() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder();
+      Assert.AreEqual(0, builder.GetExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite).Count);
+    }
+
+    [Test]
+    public void TestGetExtensionTList() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder()
+          .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 1)
+          .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 2)
+          .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 3);
+
+      IList<int> values = builder.GetExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite);
+      Assert.AreEqual(3, values.Count);
+    }
+
+    [Test]
+    public void TestGetExtensionTIndex() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder()
+          .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 0)
+          .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 1)
+          .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 2);
+
+      for(int i = 0; i < 3; i++ )
+        Assert.AreEqual(i, builder.GetExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, i));
+    }
+
+    [Test,ExpectedException(typeof(ArgumentOutOfRangeException))]
+    public void TestGetExtensionTIndexOutOfRange() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder();
+      builder.GetExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 0);
+    }
+
+    [Test]
+    public void TestSetExtensionTIndex() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder()
+          .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 0)
+          .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 1)
+          .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 2);
+
+      for (int i = 0; i < 3; i++)
+        Assert.AreEqual(i, builder.GetExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, i));
+
+      builder.SetExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 0, 5);
+      builder.SetExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 1, 6);
+      builder.SetExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 2, 7);
+
+      for (int i = 0; i < 3; i++)
+        Assert.AreEqual(5 + i, builder.GetExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, i));
+    }
+
+    [Test, ExpectedException(typeof(ArgumentOutOfRangeException))]
+    public void TestSetExtensionTIndexOutOfRange() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder();
+      builder.SetExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 0, -1);
+    }
+
+    [Test]
+    public void TestClearExtensionTList() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder()
+        .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 0);
+      Assert.AreEqual(1, builder.GetExtensionCount(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite));
+      
+      builder.ClearExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite);
+      Assert.AreEqual(0, builder.GetExtensionCount(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite));
+    }
+
+    [Test]
+    public void TestClearExtensionTValue() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder()
+        .SetExtension(UnitTestLiteProtoFile.OptionalInt32ExtensionLite, 0);
+      Assert.IsTrue(builder.HasExtension(UnitTestLiteProtoFile.OptionalInt32ExtensionLite));
+
+      builder.ClearExtension(UnitTestLiteProtoFile.OptionalInt32ExtensionLite);
+      Assert.IsFalse(builder.HasExtension(UnitTestLiteProtoFile.OptionalInt32ExtensionLite));
+    }
+
+    [Test]
+    public void TestIndexedByDescriptor() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder();
+      Assert.IsFalse(builder.HasExtension(UnitTestLiteProtoFile.OptionalInt32ExtensionLite));
+      
+      builder[UnitTestLiteProtoFile.OptionalInt32ExtensionLite.Descriptor] = 123;
+      
+      Assert.IsTrue(builder.HasExtension(UnitTestLiteProtoFile.OptionalInt32ExtensionLite));
+      Assert.AreEqual(123, builder.GetExtension(UnitTestLiteProtoFile.OptionalInt32ExtensionLite));
+    }
+
+    [Test]
+    public void TestIndexedByDescriptorAndOrdinal() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder()
+        .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 0);
+      Assert.AreEqual(1, builder.GetExtensionCount(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite));
+
+      IFieldDescriptorLite f = UnitTestLiteProtoFile.RepeatedInt32ExtensionLite.Descriptor;
+      builder[f, 0] = 123;
+
+      Assert.AreEqual(1, builder.GetExtensionCount(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite));
+      Assert.AreEqual(123, builder.GetExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 0));
+    }
+
+    [Test, ExpectedException(typeof(ArgumentOutOfRangeException))]
+    public void TestIndexedByDescriptorAndOrdinalOutOfRange() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder();
+      Assert.AreEqual(0, builder.GetExtensionCount(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite));
+
+      IFieldDescriptorLite f = UnitTestLiteProtoFile.RepeatedInt32ExtensionLite.Descriptor;
+      builder[f, 0] = 123;
+    }
+
+    [Test]
+    public void TestClearFieldByDescriptor() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder()
+        .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 0);
+      Assert.AreEqual(1, builder.GetExtensionCount(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite));
+
+      IFieldDescriptorLite f = UnitTestLiteProtoFile.RepeatedInt32ExtensionLite.Descriptor;
+      builder.ClearField(f);
+      Assert.AreEqual(0, builder.GetExtensionCount(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite));
+    }
+
+    [Test]
+    public void TestAddRepeatedFieldByDescriptor() {
+      TestAllExtensionsLite.Builder builder = TestAllExtensionsLite.CreateBuilder()
+        .AddExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 0);
+      Assert.AreEqual(1, builder.GetExtensionCount(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite));
+
+      IFieldDescriptorLite f = UnitTestLiteProtoFile.RepeatedInt32ExtensionLite.Descriptor;
+      builder.AddRepeatedField(f, 123);
+      Assert.AreEqual(2, builder.GetExtensionCount(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite));
+      Assert.AreEqual(123, builder.GetExtension(UnitTestLiteProtoFile.RepeatedInt32ExtensionLite, 1));
+    }
+  }
+}