Switched almost entirely over to Code Contracts across the entire library.

But some unit tests still fail, and there are other issues.

22 files changed, 90 insertions, 47 deletions

diff --git a/src/DotNetOpenAuth.Test/AssemblyTesting.cs b/src/DotNetOpenAuth.Test/AssemblyTesting.cs
index d0868d2..83e2242 100644
--- a/src/DotNetOpenAuth.Test/AssemblyTesting.cs
+++ b/src/DotNetOpenAuth.Test/AssemblyTesting.cs
@@ -14,10 +14,7 @@ namespace DotNetOpenAuth.Test {
 		public static void AssemblyInitialize(TestContext tc) {
 			// Make contract failures become test failures.
 			Contract.ContractFailed += (sender, e) => {
-				if (e.FailureKind == ContractFailureKind.Precondition) {
-					// Currently we ignore these so that the regular ErrorUtilities can kick in.
-					e.SetHandled();
-				} else {
+				if (e.FailureKind != ContractFailureKind.Precondition) {
 					e.SetHandled();
 					Assert.Fail(e.FailureKind.ToString() + ": " + e.Message);
 				}
diff --git a/src/DotNetOpenAuth.Test/CoordinatorBase.cs b/src/DotNetOpenAuth.Test/CoordinatorBase.cs
index d1bf27c..458ec5e 100644
--- a/src/DotNetOpenAuth.Test/CoordinatorBase.cs
+++ b/src/DotNetOpenAuth.Test/CoordinatorBase.cs
@@ -6,6 +6,7 @@
 
 namespace DotNetOpenAuth.Test {
 	using System;
+	using System.Diagnostics.Contracts;
 	using System.Threading;
 	using DotNetOpenAuth.Messaging;
 	using DotNetOpenAuth.OpenId.RelyingParty;
@@ -17,8 +18,8 @@ namespace DotNetOpenAuth.Test {
 		private Action<T2> party2Action;
 
 		protected CoordinatorBase(Action<T1> party1Action, Action<T2> party2Action) {
-			ErrorUtilities.VerifyArgumentNotNull(party1Action, "party1Action");
-			ErrorUtilities.VerifyArgumentNotNull(party2Action, "party2Action");
+			Contract.Requires<ArgumentNullException>(party1Action != null);
+			Contract.Requires<ArgumentNullException>(party2Action != null);
 
 			this.party1Action = party1Action;
 			this.party2Action = party2Action;
diff --git a/src/DotNetOpenAuth.Test/DotNetOpenAuth.Test.csproj b/src/DotNetOpenAuth.Test/DotNetOpenAuth.Test.csproj
index 32e0acc..49e9b9e 100644
--- a/src/DotNetOpenAuth.Test/DotNetOpenAuth.Test.csproj
+++ b/src/DotNetOpenAuth.Test/DotNetOpenAuth.Test.csproj
@@ -21,12 +21,12 @@
     <DefineConstants>DEBUG;TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
-    <CodeContractsEnableRuntimeChecking>False</CodeContractsEnableRuntimeChecking>
+    <CodeContractsEnableRuntimeChecking>True</CodeContractsEnableRuntimeChecking>
     <CodeContractsCustomRewriterAssembly>
     </CodeContractsCustomRewriterAssembly>
     <CodeContractsCustomRewriterClass>
     </CodeContractsCustomRewriterClass>
-    <CodeContractsRuntimeCheckingLevel>Full</CodeContractsRuntimeCheckingLevel>
+    <CodeContractsRuntimeCheckingLevel>None</CodeContractsRuntimeCheckingLevel>
     <CodeContractsRunCodeAnalysis>False</CodeContractsRunCodeAnalysis>
     <CodeContractsBuildReferenceAssembly>False</CodeContractsBuildReferenceAssembly>
     <CodeContractsNonNullObligations>False</CodeContractsNonNullObligations>
@@ -44,6 +44,8 @@
     <CodeContractsRunInBackground>True</CodeContractsRunInBackground>
     <CodeContractsShowSquigglies>False</CodeContractsShowSquigglies>
     <CodeContractsRuntimeOnlyPublicSurface>False</CodeContractsRuntimeOnlyPublicSurface>
+    <CodeContractsRuntimeThrowOnFailure>True</CodeContractsRuntimeThrowOnFailure>
+    <CodeContractsRuntimeCallSiteRequires>False</CodeContractsRuntimeCallSiteRequires>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <DebugType>pdbonly</DebugType>
@@ -52,6 +54,31 @@
     <DefineConstants>TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <CodeContractsEnableRuntimeChecking>True</CodeContractsEnableRuntimeChecking>
+    <CodeContractsCustomRewriterAssembly>
+    </CodeContractsCustomRewriterAssembly>
+    <CodeContractsCustomRewriterClass>
+    </CodeContractsCustomRewriterClass>
+    <CodeContractsRuntimeCheckingLevel>None</CodeContractsRuntimeCheckingLevel>
+    <CodeContractsRuntimeOnlyPublicSurface>False</CodeContractsRuntimeOnlyPublicSurface>
+    <CodeContractsRuntimeThrowOnFailure>True</CodeContractsRuntimeThrowOnFailure>
+    <CodeContractsRuntimeCallSiteRequires>False</CodeContractsRuntimeCallSiteRequires>
+    <CodeContractsRunCodeAnalysis>False</CodeContractsRunCodeAnalysis>
+    <CodeContractsBuildReferenceAssembly>False</CodeContractsBuildReferenceAssembly>
+    <CodeContractsNonNullObligations>False</CodeContractsNonNullObligations>
+    <CodeContractsBoundsObligations>False</CodeContractsBoundsObligations>
+    <CodeContractsArithmeticObligations>False</CodeContractsArithmeticObligations>
+    <CodeContractsLibPaths>
+    </CodeContractsLibPaths>
+    <CodeContractsPlatformPath>
+    </CodeContractsPlatformPath>
+    <CodeContractsExtraAnalysisOptions>
+    </CodeContractsExtraAnalysisOptions>
+    <CodeContractsBaseLineFile>
+    </CodeContractsBaseLineFile>
+    <CodeContractsUseBaseLine>False</CodeContractsUseBaseLine>
+    <CodeContractsRunInBackground>True</CodeContractsRunInBackground>
+    <CodeContractsShowSquigglies>False</CodeContractsShowSquigglies>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Sign)' == 'true' ">
     <SignAssembly>true</SignAssembly>
@@ -71,7 +98,7 @@
     </CodeContractsCustomRewriterAssembly>
     <CodeContractsCustomRewriterClass>
     </CodeContractsCustomRewriterClass>
-    <CodeContractsRuntimeCheckingLevel>Full</CodeContractsRuntimeCheckingLevel>
+    <CodeContractsRuntimeCheckingLevel>None</CodeContractsRuntimeCheckingLevel>
     <CodeContractsRunCodeAnalysis>True</CodeContractsRunCodeAnalysis>
     <CodeContractsBuildReferenceAssembly>False</CodeContractsBuildReferenceAssembly>
     <CodeContractsNonNullObligations>False</CodeContractsNonNullObligations>
@@ -87,6 +114,10 @@
     <CodeContractsUseBaseLine>False</CodeContractsUseBaseLine>
     <CodeContractsRunInBackground>True</CodeContractsRunInBackground>
     <CodeContractsShowSquigglies>True</CodeContractsShowSquigglies>
+    <CodeContractsRuntimeOnlyPublicSurface>False</CodeContractsRuntimeOnlyPublicSurface>
+    <CodeContractsRuntimeThrowOnFailure>True</CodeContractsRuntimeThrowOnFailure>
+    <CodeContractsRuntimeCallSiteRequires>False</CodeContractsRuntimeCallSiteRequires>
+    <CodeContractsArithmeticObligations>False</CodeContractsArithmeticObligations>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=1b44e1d426115821, processorArchitecture=MSIL">
diff --git a/src/DotNetOpenAuth.Test/Messaging/Bindings/StandardReplayProtectionBindingElementTests.cs b/src/DotNetOpenAuth.Test/Messaging/Bindings/StandardReplayProtectionBindingElementTests.cs
index 26ce01c..14651bc 100644
--- a/src/DotNetOpenAuth.Test/Messaging/Bindings/StandardReplayProtectionBindingElementTests.cs
+++ b/src/DotNetOpenAuth.Test/Messaging/Bindings/StandardReplayProtectionBindingElementTests.cs
@@ -31,6 +31,7 @@ namespace DotNetOpenAuth.Test.Messaging.Bindings {
 			this.protocol = Protocol.Default;
 			this.nonceStore = new NonceMemoryStore(TimeSpan.FromHours(3));
 			this.nonceElement = new StandardReplayProtectionBindingElement(this.nonceStore);
+			this.nonceElement.Channel = new Mocks.TestChannel();
 			this.message = new TestReplayProtectedMessage();
 			this.message.UtcCreationDate = DateTime.UtcNow;
 		}
diff --git a/src/DotNetOpenAuth.Test/Messaging/CollectionAssert.cs b/src/DotNetOpenAuth.Test/Messaging/CollectionAssert.cs
index f9e569a..db136f5 100644
--- a/src/DotNetOpenAuth.Test/Messaging/CollectionAssert.cs
+++ b/src/DotNetOpenAuth.Test/Messaging/CollectionAssert.cs
@@ -5,16 +5,18 @@
 //-----------------------------------------------------------------------
 
 namespace DotNetOpenAuth.Test.Messaging {
+	using System;
 	using System.Collections;
 	using System.Collections.Generic;
+	using System.Diagnostics.Contracts;
 	using System.Linq;
 	using DotNetOpenAuth.Messaging;
 	using Microsoft.VisualStudio.TestTools.UnitTesting;
 
 	internal class CollectionAssert<T> {
 		internal static void AreEquivalent(ICollection<T> expected, ICollection<T> actual) {
-			ErrorUtilities.VerifyArgumentNotNull(expected, "expected");
-			ErrorUtilities.VerifyArgumentNotNull(actual, "actual");
+			Contract.Requires<ArgumentNullException>(expected != null);
+			Contract.Requires<ArgumentNullException>(actual != null);
 
 			ICollection expectedNonGeneric = new List<T>(expected);
 			ICollection actualNonGeneric = new List<T>(actual);
@@ -22,8 +24,8 @@ namespace DotNetOpenAuth.Test.Messaging {
 		}
 
 		internal static void AreEquivalentByEquality(ICollection<T> expected, ICollection<T> actual) {
-			ErrorUtilities.VerifyArgumentNotNull(expected, "expected");
-			ErrorUtilities.VerifyArgumentNotNull(actual, "actual");
+			Contract.Requires<ArgumentNullException>(expected != null);
+			Contract.Requires<ArgumentNullException>(actual != null);
 
 			Assert.AreEqual(expected.Count, actual.Count);
 			foreach (T value in expected) {
@@ -32,7 +34,7 @@ namespace DotNetOpenAuth.Test.Messaging {
 		}
 
 		internal static void Contains(IEnumerable<T> sequence, T element) {
-			ErrorUtilities.VerifyArgumentNotNull(sequence, "sequence");
+			Contract.Requires<ArgumentNullException>(sequence != null);
 
 			if (!sequence.Contains(element)) {
 				Assert.Fail("Sequence did not include expected element '{0}'.", element);
diff --git a/src/DotNetOpenAuth.Test/Mocks/CoordinatingChannel.cs b/src/DotNetOpenAuth.Test/Mocks/CoordinatingChannel.cs
index 3bbe6e3..16386de 100644
--- a/src/DotNetOpenAuth.Test/Mocks/CoordinatingChannel.cs
+++ b/src/DotNetOpenAuth.Test/Mocks/CoordinatingChannel.cs
@@ -7,6 +7,7 @@
 namespace DotNetOpenAuth.Test.Mocks {
 	using System;
 	using System.Collections.Generic;
+	using System.Diagnostics.Contracts;
 	using System.Linq;
 	using System.Text;
 	using System.Threading;
@@ -84,7 +85,7 @@ namespace DotNetOpenAuth.Test.Mocks {
 		/// <param name="outgoingMessageFilter">The outgoing message filter.  May be null.</param>
 		internal CoordinatingChannel(Channel wrappedChannel, Action<IProtocolMessage> incomingMessageFilter, Action<IProtocolMessage> outgoingMessageFilter)
 			: base(GetMessageFactory(wrappedChannel), wrappedChannel.BindingElements.ToArray()) {
-			ErrorUtilities.VerifyArgumentNotNull(wrappedChannel, "wrappedChannel");
+			Contract.Requires<ArgumentNullException>(wrappedChannel != null);
 
 			this.wrappedChannel = wrappedChannel;
 			this.incomingMessageFilter = incomingMessageFilter;
@@ -220,7 +221,7 @@ namespace DotNetOpenAuth.Test.Mocks {
 		/// channel since their message factory is not used.
 		/// </remarks>
 		protected virtual T CloneSerializedParts<T>(T message) where T : class, IProtocolMessage {
-			ErrorUtilities.VerifyArgumentNotNull(message, "message");
+			Contract.Requires<ArgumentNullException>(message != null);
 
 			IProtocolMessage clonedMessage;
 			var messageAccessor = this.MessageDescriptions.GetAccessor(message);
@@ -251,7 +252,7 @@ namespace DotNetOpenAuth.Test.Mocks {
 		}
 
 		private static IMessageFactory GetMessageFactory(Channel channel) {
-			ErrorUtilities.VerifyArgumentNotNull(channel, "channel");
+			Contract.Requires<ArgumentNullException>(channel != null);
 
 			Channel_Accessor accessor = Channel_Accessor.AttachShadow(channel);
 			return accessor.MessageFactory;
diff --git a/src/DotNetOpenAuth.Test/Mocks/CoordinatingOAuthChannel.cs b/src/DotNetOpenAuth.Test/Mocks/CoordinatingOAuthChannel.cs
index 2d14bc8..2e4ccad 100644
--- a/src/DotNetOpenAuth.Test/Mocks/CoordinatingOAuthChannel.cs
+++ b/src/DotNetOpenAuth.Test/Mocks/CoordinatingOAuthChannel.cs
@@ -6,6 +6,7 @@
 
 namespace DotNetOpenAuth.Test.Mocks {
 	using System;
+	using System.Diagnostics.Contracts;
 	using System.Threading;
 	using DotNetOpenAuth.Messaging;
 	using DotNetOpenAuth.Messaging.Bindings;
@@ -134,7 +135,7 @@ namespace DotNetOpenAuth.Test.Mocks {
 		}
 
 		private T CloneSerializedParts<T>(T message, HttpRequestInfo requestInfo) where T : class, IProtocolMessage {
-			ErrorUtilities.VerifyArgumentNotNull(message, "message");
+			Contract.Requires<ArgumentNullException>(message != null);
 
 			IProtocolMessage clonedMessage;
 			var messageAccessor = this.MessageDescriptions.GetAccessor(message);
diff --git a/src/DotNetOpenAuth.Test/Mocks/CoordinatingOutgoingWebResponse.cs b/src/DotNetOpenAuth.Test/Mocks/CoordinatingOutgoingWebResponse.cs
index 07f9bc9..62ea871 100644
--- a/src/DotNetOpenAuth.Test/Mocks/CoordinatingOutgoingWebResponse.cs
+++ b/src/DotNetOpenAuth.Test/Mocks/CoordinatingOutgoingWebResponse.cs
@@ -7,6 +7,7 @@
 namespace DotNetOpenAuth.Test.Mocks {
 	using System;
 	using System.Collections.Generic;
+	using System.Diagnostics.Contracts;
 	using System.Linq;
 	using System.Text;
 	using DotNetOpenAuth.Messaging;
@@ -20,8 +21,8 @@ namespace DotNetOpenAuth.Test.Mocks {
 		/// <param name="message">The direct response message to send to the remote channel.  This message will be cloned.</param>
 		/// <param name="receivingChannel">The receiving channel.</param>
 		internal CoordinatingOutgoingWebResponse(IProtocolMessage message, CoordinatingChannel receivingChannel) {
-			ErrorUtilities.VerifyArgumentNotNull(message, "message");
-			ErrorUtilities.VerifyArgumentNotNull(receivingChannel, "receivingChannel");
+			Contract.Requires<ArgumentNullException>(message != null);
+			Contract.Requires<ArgumentNullException>(receivingChannel != null);
 
 			this.receivingChannel = receivingChannel;
 			this.OriginalMessage = message;
diff --git a/src/DotNetOpenAuth.Test/Mocks/MockHttpRequest.cs b/src/DotNetOpenAuth.Test/Mocks/MockHttpRequest.cs
index 66f258d..0213a33 100644
--- a/src/DotNetOpenAuth.Test/Mocks/MockHttpRequest.cs
+++ b/src/DotNetOpenAuth.Test/Mocks/MockHttpRequest.cs
@@ -7,6 +7,7 @@
 namespace DotNetOpenAuth.Test.Mocks {
 	using System;
 	using System.Collections.Generic;
+	using System.Diagnostics.Contracts;
 	using System.Globalization;
 	using System.IO;
 	using System.Net;
@@ -22,7 +23,7 @@ namespace DotNetOpenAuth.Test.Mocks {
 		private readonly Dictionary<Uri, IncomingWebResponse> registeredMockResponses = new Dictionary<Uri, IncomingWebResponse>();
 
 		private MockHttpRequest(IDirectWebRequestHandler mockHandler) {
-			ErrorUtilities.VerifyArgumentNotNull(mockHandler, "mockHandler");
+			Contract.Requires<ArgumentNullException>(mockHandler != null);
 			this.MockWebRequestHandler = mockHandler;
 		}
 
@@ -41,7 +42,7 @@ namespace DotNetOpenAuth.Test.Mocks {
 		}
 
 		internal void RegisterMockResponse(IncomingWebResponse response) {
-			ErrorUtilities.VerifyArgumentNotNull(response, "response");
+			Contract.Requires<ArgumentNullException>(response != null);
 			if (this.registeredMockResponses.ContainsKey(response.RequestUri)) {
 				Logger.Http.WarnFormat("Mock HTTP response already registered for {0}.", response.RequestUri);
 			} else {
@@ -58,9 +59,9 @@ namespace DotNetOpenAuth.Test.Mocks {
 		}
 
 		internal void RegisterMockResponse(Uri requestUri, Uri responseUri, string contentType, WebHeaderCollection headers, string responseBody) {
-			ErrorUtilities.VerifyArgumentNotNull(requestUri, "requestUri");
-			ErrorUtilities.VerifyArgumentNotNull(responseUri, "responseUri");
-			ErrorUtilities.VerifyNonZeroLength(contentType, "contentType");
+			Contract.Requires<ArgumentNullException>(requestUri != null);
+			Contract.Requires<ArgumentNullException>(responseUri != null);
+			Contract.Requires<ArgumentException>(!String.IsNullOrEmpty(contentType));
 
 			// Set up the redirect if appropriate
 			if (requestUri != responseUri) {
@@ -83,7 +84,7 @@ namespace DotNetOpenAuth.Test.Mocks {
 		}
 
 		internal void RegisterMockXrdsResponse(ServiceEndpoint endpoint) {
-			ErrorUtilities.VerifyArgumentNotNull(endpoint, "endpoint");
+			Contract.Requires<ArgumentNullException>(endpoint != null);
 
 			string identityUri;
 			if (endpoint.ClaimedIdentifier == endpoint.Protocol.ClaimedIdentifierForOPIdentifier) {
@@ -95,7 +96,7 @@ namespace DotNetOpenAuth.Test.Mocks {
 		}
 
 		internal void RegisterMockXrdsResponse(Uri respondingUri, IEnumerable<ServiceEndpoint> endpoints) {
-			ErrorUtilities.VerifyArgumentNotNull(endpoints, "endpoints");
+			Contract.Requires<ArgumentNullException>(endpoints != null);
 
 			StringBuilder xrds = new StringBuilder();
 			xrds.AppendLine(@"<xrds:XRDS xmlns:xrds='xri://$xrds' xmlns:openid='http://openid.net/xmlns/1.0' xmlns='xri://$xrd*($v*2.0)'>
diff --git a/src/DotNetOpenAuth.Test/Mocks/MockIdentifier.cs b/src/DotNetOpenAuth.Test/Mocks/MockIdentifier.cs
index 669e4d3..2788435 100644
--- a/src/DotNetOpenAuth.Test/Mocks/MockIdentifier.cs
+++ b/src/DotNetOpenAuth.Test/Mocks/MockIdentifier.cs
@@ -7,6 +7,7 @@
 namespace DotNetOpenAuth.Test.Mocks {
 	using System;
 	using System.Collections.Generic;
+	using System.Diagnostics.Contracts;
 	using DotNetOpenAuth.Messaging;
 	using DotNetOpenAuth.OpenId;
 	using DotNetOpenAuth.OpenId.RelyingParty;
@@ -25,9 +26,9 @@ namespace DotNetOpenAuth.Test.Mocks {
 
 		public MockIdentifier(Identifier wrappedIdentifier, MockHttpRequest mockHttpRequest, IEnumerable<ServiceEndpoint> endpoints)
 			: base(false) {
-			ErrorUtilities.VerifyArgumentNotNull(wrappedIdentifier, "wrappedIdentifier");
-			ErrorUtilities.VerifyArgumentNotNull(mockHttpRequest, "mockHttpRequest");
-			ErrorUtilities.VerifyArgumentNotNull(endpoints, "endpoints");
+			Contract.Requires<ArgumentNullException>(wrappedIdentifier != null);
+			Contract.Requires<ArgumentNullException>(mockHttpRequest != null);
+			Contract.Requires<ArgumentNullException>(endpoints != null);
 
 			this.wrappedIdentifier = wrappedIdentifier;
 			this.endpoints = endpoints;
diff --git a/src/DotNetOpenAuth.Test/Mocks/TestMessageFactory.cs b/src/DotNetOpenAuth.Test/Mocks/TestMessageFactory.cs
index ffb117c..7b13175 100644
--- a/src/DotNetOpenAuth.Test/Mocks/TestMessageFactory.cs
+++ b/src/DotNetOpenAuth.Test/Mocks/TestMessageFactory.cs
@@ -7,6 +7,7 @@
 namespace DotNetOpenAuth.Test.Mocks {
 	using System;
 	using System.Collections.Generic;
+	using System.Diagnostics.Contracts;
 	using System.Linq;
 	using System.Text;
 	using DotNetOpenAuth.Messaging;
@@ -32,8 +33,6 @@ namespace DotNetOpenAuth.Test.Mocks {
 		#region IMessageFactory Members
 
 		public IDirectedProtocolMessage GetNewRequestMessage(MessageReceivingEndpoint recipient, IDictionary<string, string> fields) {
-			ErrorUtilities.VerifyArgumentNotNull(fields, "fields");
-
 			if (fields.ContainsKey("age")) {
 				if (this.signedMessages) {
 					if (this.expiringMessages) {
diff --git a/src/DotNetOpenAuth.Test/Mocks/TestWebRequestHandler.cs b/src/DotNetOpenAuth.Test/Mocks/TestWebRequestHandler.cs
index b74c0f0..03dbd6b 100644
--- a/src/DotNetOpenAuth.Test/Mocks/TestWebRequestHandler.cs
+++ b/src/DotNetOpenAuth.Test/Mocks/TestWebRequestHandler.cs
@@ -56,7 +56,7 @@ namespace DotNetOpenAuth.Test.Mocks {
 		#region IWebRequestHandler Members
 
 		public bool CanSupport(DirectWebRequestOptions options) {
-			return options == DirectWebRequestOptions.None;
+			return true;
 		}
 
 		/// <summary>
diff --git a/src/DotNetOpenAuth.Test/OAuth/ChannelElements/OAuthChannelTests.cs b/src/DotNetOpenAuth.Test/OAuth/ChannelElements/OAuthChannelTests.cs
index 449a033..923e6c1 100644
--- a/src/DotNetOpenAuth.Test/OAuth/ChannelElements/OAuthChannelTests.cs
+++ b/src/DotNetOpenAuth.Test/OAuth/ChannelElements/OAuthChannelTests.cs
@@ -8,6 +8,7 @@ namespace DotNetOpenAuth.Test.ChannelElements {
 	using System;
 	using System.Collections.Generic;
 	using System.Collections.Specialized;
+	using System.Diagnostics.Contracts;
 	using System.IO;
 	using System.Net;
 	using System.Text;
@@ -243,7 +244,7 @@ namespace DotNetOpenAuth.Test.ChannelElements {
 		}
 
 		private static string CreateAuthorizationHeader(IDictionary<string, string> fields) {
-			ErrorUtilities.VerifyArgumentNotNull(fields, "fields");
+			Contract.Requires<ArgumentNullException>(fields != null);
 
 			StringBuilder authorization = new StringBuilder();
 			authorization.Append("OAuth ");
diff --git a/src/DotNetOpenAuth.Test/OAuth/OAuthCoordinator.cs b/src/DotNetOpenAuth.Test/OAuth/OAuthCoordinator.cs
index e04edeb..4373402 100644
--- a/src/DotNetOpenAuth.Test/OAuth/OAuthCoordinator.cs
+++ b/src/DotNetOpenAuth.Test/OAuth/OAuthCoordinator.cs
@@ -6,6 +6,7 @@
 
 namespace DotNetOpenAuth.Test {
 	using System;
+	using System.Diagnostics.Contracts;
 	using DotNetOpenAuth.Messaging;
 	using DotNetOpenAuth.OAuth;
 	using DotNetOpenAuth.OAuth.ChannelElements;
@@ -25,8 +26,8 @@ namespace DotNetOpenAuth.Test {
 		/// <param name="serviceProviderAction">The code path of the Service Provider.</param>
 		internal OAuthCoordinator(ConsumerDescription consumerDescription, ServiceProviderDescription serviceDescription, Action<WebConsumer> consumerAction, Action<ServiceProvider> serviceProviderAction)
 			: base(consumerAction, serviceProviderAction) {
-			ErrorUtilities.VerifyArgumentNotNull(consumerDescription, "consumerDescription");
-			ErrorUtilities.VerifyArgumentNotNull(serviceDescription, "serviceDescription");
+			Contract.Requires<ArgumentNullException>(consumerDescription != null);
+			Contract.Requires<ArgumentNullException>(serviceDescription != null);
 
 			this.consumerDescription = consumerDescription;
 			this.serviceDescription = serviceDescription;
diff --git a/src/DotNetOpenAuth.Test/OpenId/AuthenticationTests.cs b/src/DotNetOpenAuth.Test/OpenId/AuthenticationTests.cs
index 4ebdf74..7de2a8b 100644
--- a/src/DotNetOpenAuth.Test/OpenId/AuthenticationTests.cs
+++ b/src/DotNetOpenAuth.Test/OpenId/AuthenticationTests.cs
@@ -6,6 +6,7 @@
 
 namespace DotNetOpenAuth.Test.OpenId {
 	using System;
+	using System.Diagnostics.Contracts;
 	using DotNetOpenAuth.Messaging;
 	using DotNetOpenAuth.Messaging.Bindings;
 	using DotNetOpenAuth.OpenId;
@@ -135,8 +136,8 @@ namespace DotNetOpenAuth.Test.OpenId {
 		}
 
 		private void ParameterizedAuthenticationTest(Protocol protocol, bool statelessRP, bool sharedAssociation, bool positive, bool immediate, bool tamper) {
-			ErrorUtilities.VerifyArgument(!statelessRP || !sharedAssociation, "The RP cannot be stateless while sharing an association with the OP.");
-			ErrorUtilities.VerifyArgument(positive || !tamper, "Cannot tamper with a negative response.");
+			Contract.Requires<ArgumentException>(!statelessRP || !sharedAssociation, "The RP cannot be stateless while sharing an association with the OP.");
+			Contract.Requires<ArgumentException>(positive || !tamper, "Cannot tamper with a negative response.");
 			ProviderSecuritySettings securitySettings = new ProviderSecuritySettings();
 			Association association = sharedAssociation ? HmacShaAssociation.Create(protocol, protocol.Args.SignatureAlgorithm.Best, AssociationRelyingPartyType.Smart, securitySettings) : null;
 			var coordinator = new OpenIdCoordinator(
diff --git a/src/DotNetOpenAuth.Test/OpenId/ChannelElements/ExtensionsBindingElementTests.cs b/src/DotNetOpenAuth.Test/OpenId/ChannelElements/ExtensionsBindingElementTests.cs
index 12f6e7a..08432ff 100644
--- a/src/DotNetOpenAuth.Test/OpenId/ChannelElements/ExtensionsBindingElementTests.cs
+++ b/src/DotNetOpenAuth.Test/OpenId/ChannelElements/ExtensionsBindingElementTests.cs
@@ -7,6 +7,7 @@
 namespace DotNetOpenAuth.Test.OpenId.ChannelElements {
 	using System;
 	using System.Collections.Generic;
+	using System.Diagnostics.Contracts;
 	using System.Linq;
 	using System.Text.RegularExpressions;
 	using DotNetOpenAuth.Messaging;
@@ -167,7 +168,7 @@ namespace DotNetOpenAuth.Test.OpenId.ChannelElements {
 		}
 
 		private static void RegisterMockExtension(Channel channel) {
-			ErrorUtilities.VerifyArgumentNotNull(channel, "channel");
+			Contract.Requires<ArgumentNullException>(channel != null);
 
 			ExtensionTestUtilities.RegisterExtension(channel, MockOpenIdExtension.Factory);
 		}
@@ -178,7 +179,7 @@ namespace DotNetOpenAuth.Test.OpenId.ChannelElements {
 		/// <param name="protocol">The protocol to construct the message with.</param>
 		/// <returns>The message ready to send from OP to RP.</returns>
 		private IndirectSignedResponse CreateResponseWithExtensions(Protocol protocol) {
-			ErrorUtilities.VerifyArgumentNotNull(protocol, "protocol");
+			Contract.Requires<ArgumentNullException>(protocol != null);
 
 			IndirectSignedResponse response = new IndirectSignedResponse(protocol.Version, RPUri);
 			response.ProviderEndpoint = OPUri;
diff --git a/src/DotNetOpenAuth.Test/OpenId/Extensions/AttributeExchange/AttributeRequestTests.cs b/src/DotNetOpenAuth.Test/OpenId/Extensions/AttributeExchange/AttributeRequestTests.cs
index 228bda3..48b5727 100644
--- a/src/DotNetOpenAuth.Test/OpenId/Extensions/AttributeExchange/AttributeRequestTests.cs
+++ b/src/DotNetOpenAuth.Test/OpenId/Extensions/AttributeExchange/AttributeRequestTests.cs
@@ -25,7 +25,7 @@ namespace DotNetOpenAuth.Test.OpenId.Extensions {
 			new AttributeRequest(string.Empty);
 		}
 
-		[TestMethod, ExpectedException(typeof(ArgumentNullException))]
+		[TestMethod, ExpectedException(typeof(ArgumentException))]
 		public void CtorNullTypeUri() {
 			new AttributeRequest(null);
 		}
diff --git a/src/DotNetOpenAuth.Test/OpenId/Extensions/ExtensionTestUtilities.cs b/src/DotNetOpenAuth.Test/OpenId/Extensions/ExtensionTestUtilities.cs
index 47c8ec4..334fc93 100644
--- a/src/DotNetOpenAuth.Test/OpenId/Extensions/ExtensionTestUtilities.cs
+++ b/src/DotNetOpenAuth.Test/OpenId/Extensions/ExtensionTestUtilities.cs
@@ -5,7 +5,9 @@
 //-----------------------------------------------------------------------
 
 namespace DotNetOpenAuth.Test.OpenId.Extensions {
+	using System;
 	using System.Collections.Generic;
+	using System.Diagnostics.Contracts;
 	using System.Linq;
 	using DotNetOpenAuth.Messaging;
 	using DotNetOpenAuth.OpenId;
@@ -71,7 +73,7 @@ namespace DotNetOpenAuth.Test.OpenId.Extensions {
 		}
 
 		internal static void RegisterExtension(Channel channel, StandardOpenIdExtensionFactory.CreateDelegate extensionFactory) {
-			ErrorUtilities.VerifyArgumentNotNull(channel, "channel");
+			Contract.Requires<ArgumentNullException>(channel != null);
 
 			var factory = (OpenIdExtensionFactoryAggregator)channel.BindingElements.OfType<ExtensionsBindingElement>().Single().ExtensionFactory;
 			factory.Factories.OfType<StandardOpenIdExtensionFactory>().Single().RegisterExtension(extensionFactory);
diff --git a/src/DotNetOpenAuth.Test/OpenId/IdentifierTests.cs b/src/DotNetOpenAuth.Test/OpenId/IdentifierTests.cs
index 3e599e9..cc02265 100644
--- a/src/DotNetOpenAuth.Test/OpenId/IdentifierTests.cs
+++ b/src/DotNetOpenAuth.Test/OpenId/IdentifierTests.cs
@@ -75,7 +75,7 @@ namespace DotNetOpenAuth.Test.OpenId {
 			Assert.AreEqual(this.uri, ((UriIdentifier)id).Uri.AbsoluteUri);
 		}
 
-		[TestMethod, ExpectedException(typeof(ArgumentNullException))]
+		[TestMethod, ExpectedException(typeof(ArgumentException))]
 		public void ParseNull() {
 			Identifier.Parse(null);
 		}
diff --git a/src/DotNetOpenAuth.Test/OpenId/OpenIdCoordinator.cs b/src/DotNetOpenAuth.Test/OpenId/OpenIdCoordinator.cs
index af9c5db..0f9d472 100644
--- a/src/DotNetOpenAuth.Test/OpenId/OpenIdCoordinator.cs
+++ b/src/DotNetOpenAuth.Test/OpenId/OpenIdCoordinator.cs
@@ -6,6 +6,7 @@
 
 namespace DotNetOpenAuth.Test.OpenId {
 	using System;
+	using System.Diagnostics.Contracts;
 	using DotNetOpenAuth.Messaging;
 	using DotNetOpenAuth.Messaging.Bindings;
 	using DotNetOpenAuth.OpenId;
@@ -36,7 +37,7 @@ namespace DotNetOpenAuth.Test.OpenId {
 		}
 
 		private static Action<OpenIdRelyingParty> WrapAction(Action<OpenIdRelyingParty> action) {
-			ErrorUtilities.VerifyArgumentNotNull(action, "action");
+			Contract.Requires<ArgumentNullException>(action != null);
 
 			return rp => {
 				action(rp);
@@ -45,7 +46,7 @@ namespace DotNetOpenAuth.Test.OpenId {
 		}
 
 		private static Action<OpenIdProvider> WrapAction(Action<OpenIdProvider> action) {
-			ErrorUtilities.VerifyArgumentNotNull(action, "action");
+			Contract.Requires<ArgumentNullException>(action != null);
 
 			return op => {
 				action(op);
diff --git a/src/DotNetOpenAuth.Test/OpenId/UriIdentifierTests.cs b/src/DotNetOpenAuth.Test/OpenId/UriIdentifierTests.cs
index 3b3f985..92379da 100644
--- a/src/DotNetOpenAuth.Test/OpenId/UriIdentifierTests.cs
+++ b/src/DotNetOpenAuth.Test/OpenId/UriIdentifierTests.cs
@@ -31,7 +31,7 @@ namespace DotNetOpenAuth.Test.OpenId {
 			new UriIdentifier((Uri)null);
 		}
 
-		[TestMethod, ExpectedException(typeof(ArgumentNullException))]
+		[TestMethod, ExpectedException(typeof(ArgumentException))]
 		public void CtorNullString() {
 			new UriIdentifier((string)null);
 		}
diff --git a/src/DotNetOpenAuth.Test/Properties/AssemblyInfo.cs b/src/DotNetOpenAuth.Test/Properties/AssemblyInfo.cs
index d6fd020..4744bfe 100644
--- a/src/DotNetOpenAuth.Test/Properties/AssemblyInfo.cs
+++ b/src/DotNetOpenAuth.Test/Properties/AssemblyInfo.cs
@@ -29,4 +29,4 @@ using System.Runtime.InteropServices;
 // The following GUID is for the ID of the typelib if this project is exposed to COM
 [assembly: Guid("aef0bb13-b79c-4854-a69a-de58b8feb5d1")]
 
-[assembly: ContractVerification(false)]
\ No newline at end of file
+[assembly: ContractVerification(true)]
\ No newline at end of file