Added check for null model in ViewResultBaseAssertions.

Author: kevinkuszyk

src/FluentAssertions.Mvc3/FailureMessages.Designer.cs

@@ -117,6 +117,9 @@
   <resheader name="writer">
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
+  <data name="ViewResultBase_NullModel" xml:space="preserve">
+    <value>Expected Model to be of type {0}, but no Model was supplied.</value>
+  </data>
   <data name="ViewResultBase_WithDefaultViewName" xml:space="preserve">
     <value>Expected default view, but view {0} was rendered.</value>
   </data>

src/FluentAssertions.Mvc3/FailureMessages.resx

@@ -88,6 +88,9 @@ public TModel ModelAs<TModel>()
         {
             object model = (Subject as ViewResultBase).Model;
 
+            if (model == null)
+                Execute.Verification.FailWith(FailureMessages.ViewResultBase_NullModel, typeof(TModel).Name);
+
             Execute.Verification
                     .ForCondition(model is TModel)
                     .FailWith("Expected Model to be of type '{0}' but was '{1}'", typeof(TModel).Name, model.GetType().Name);

src/FluentAssertions.Mvc3/ViewResultBaseAssertions.cs

@@ -229,6 +229,21 @@ public void ModelAs_GivenWrongType_ShouldFail()
                     .WithMessage("");
         }
 
+        [Test]
+        public void ModelAs_Null_ShouldFail()
+        {
+            ActionResult result = new ViewResult();
+
+            // TODO: Improve the comparision of failure messages.
+            string value = String.Format("\"{0}\"", typeof(Object).Name);
+            string failureMessage = String.Format(FailureMessages.ViewResultBase_NullModel, value);
+
+            Action a = () => result.Should().BeView().ModelAs<Object>();
+            
+            a.ShouldThrow<Exception>()
+                    .WithMessage(failureMessage);
+        }
+
         [Test]
         public void WithDefaultViewName_GivenExpectedValue_ShouldPass()
         {
@@ -244,6 +259,8 @@ public void WithDefaultViewName_GivenExpectedValue_ShouldPass()
         public void WithDefaultViewName_GivenUnexpectedValue_ShouldFail()
         {
             string viewName = "index";
+
+            // TODO: Improve the comparision of failure messages.
             string value = String.Format("\"{0}\"", viewName);
             string failureMessage = String.Format(FailureMessages.ViewResultBase_WithDefaultViewName, value);