Added tests and fix for view location error.

Processors are now no longer wrapped in a safe execution method
so exceptions are bubbled up. Returning null from a propcessor
will execute the next one, so if anything goes wrong when processing
in your processor.. catch it, log it, return null :-)

src/Nancy.Tests.Functional/Tests/ContentNegotiationFixture.cs

@@ -4,6 +4,7 @@ namespace Nancy.Tests.Functional.Tests
     using System.Collections.Generic;
     using System.IO;
 
+    using Nancy.ErrorHandling;
     using Nancy.IO;
     using Nancy.Responses.Negotiation;
     using Nancy.Testing;
@@ -372,22 +373,6 @@ public void Should_add_link_header_for_matching_response_processors()
             Assert.True(response.Headers["Link"].Contains(@"</.xml>; rel=""application/xml"""));
         }
 
-        private static Func<dynamic, dynamic> CreateNegotiatedResponse(Action<Negotiator> action = null)
-        {
-            var context =
-                new NancyContext { NegotiationContext = new NegotiationContext() };
-
-            var negotiator =
-                new Negotiator(context);
-
-            if (action != null)
-            {
-                action.Invoke(negotiator);
-            }
-
-            return parameters => negotiator;
-        }
-
         [Fact]
         public void Should_set_negotiated_status_code_to_response_when_set_as_integer()
         {
@@ -442,6 +427,77 @@ public void Should_set_negotiated_status_code_to_response_when_set_as_httpstatus
             Assert.Equal(HttpStatusCode.InsufficientStorage, response.StatusCode);
         }
 
+        [Fact]
+        public void Should_throw_exception_if_view_location_fails()
+        {
+            var browser = new Browser(with =>
+            {
+                with.ResponseProcessor<ViewProcessor>();
+
+                with.Module(new FakeModuleInvalidViewName());
+            });
+
+            // When
+            var result = Record.Exception(() =>
+                {
+                    var response = browser.Get(
+                        "/FakeModuleInvalidViewName",
+                        with =>
+                            { with.Accept("text/html", 1.0m); });
+                });
+
+            // Then
+            Assert.NotNull(result);
+            Assert.Contains("Unable to locate view", result.ToString());
+        }
+
+        [Fact]
+        public void Should_use_next_processor_if_processor_returns_null()
+        {
+            // Given
+            var browser = new Browser(with =>
+                {
+                with.ResponseProcessors(typeof(NullProcessor), typeof(TestProcessor));
+
+                with.Module(new ConfigurableNancyModule(x =>
+                {
+                    x.Get("/test", CreateNegotiatedResponse(config =>
+                    {
+                        config.WithAllowedMediaRange("application/xml");
+                    }));
+                }));
+            });
+
+            // When
+            var response = browser.Get("/test", with =>
+            {
+                with.Accept("application/xml", 0.9m);
+            });
+
+            // Then
+            var bodyResult = response.Body.AsString();
+            Assert.True(bodyResult.StartsWith("application/xml"), string.Format("Body should have started with 'application/xml' but was actually '{0}'", bodyResult));
+        }
+
+        private static Func<dynamic, dynamic> CreateNegotiatedResponse(Action<Negotiator> action = null)
+        {
+            var context =
+                new NancyContext { NegotiationContext = new NegotiationContext() };
+
+            var negotiator =
+                new Negotiator(context);
+
+            if (action != null)
+            {
+                action.Invoke(negotiator);
+            }
+
+            return parameters =>
+                {
+                    return negotiator;
+                };
+        }
+
         /// <summary>
         /// Test response processor that will accept any type
         /// and put the content type and model type into the
@@ -475,6 +531,33 @@ public Response Process(MediaRange requestedMediaRange, dynamic model, NancyCont
             }
         }
 
+        public class NullProcessor : IResponseProcessor
+        {
+            private const string ResponseTemplate = "{0}\n{1}";
+
+            public IEnumerable<Tuple<string, MediaRange>> ExtensionMappings
+            {
+                get
+                {
+                    yield break;
+                }
+            }
+
+            public ProcessorMatch CanProcess(MediaRange requestedMediaRange, dynamic model, NancyContext context)
+            {
+                return new ProcessorMatch
+                {
+                    RequestedContentTypeResult = MatchResult.ExactMatch,
+                    ModelResult = MatchResult.ExactMatch
+                };
+            }
+
+            public Response Process(MediaRange requestedMediaRange, dynamic model, NancyContext context)
+            {
+                return null;
+            }
+        }
+
         public class ModelProcessor : IResponseProcessor
         {
             private const string ResponseTemplate = "{0}\n{1}";
@@ -501,5 +584,13 @@ public Response Process(MediaRange requestedMediaRange, dynamic model, NancyCont
                 return (string) model;
             }
         }
+
+        public class FakeModuleInvalidViewName : NancyModule
+        {
+            public FakeModuleInvalidViewName()
+            {
+                Get["/FakeModuleInvalidViewName"] = _ => View["blahblahblah"];
+            }
+        }
     }
 }

src/Nancy/Routing/DefaultRouteInvoker.cs

@@ -100,7 +100,7 @@ private static Response NegotiateResponse(IEnumerable<Tuple<string, IEnumerable<
                     context.WriteTraceLog(sb => sb.AppendFormat("[DefaultRouteInvoker] Invoking processor: {0}\n", processorType));
 
                     var response =
-                        SafeInvokeResponseProcessor(prioritizedProcessor.Item1, compatibleHeader.Item1, negotiator.NegotiationContext.GetModelForMediaRange(compatibleHeader.Item1), context);
+                        prioritizedProcessor.Item1.Process(compatibleHeader.Item1, negotiator.NegotiationContext.GetModelForMediaRange(compatibleHeader.Item1), context);
 
                     if (response != null)
                     {
@@ -247,20 +247,6 @@ private IEnumerable<Tuple<string, decimal>> GetCoercedAcceptHeaders(NancyContext
             return currentHeaders;
         }
 
-        private static Response SafeInvokeResponseProcessor(IResponseProcessor responseProcessor, MediaRange mediaRange, object model, NancyContext context)
-        {
-            try
-            {
-                return responseProcessor.Process(mediaRange, model, context);
-            }
-            catch (Exception e)
-            {
-                context.WriteTraceLog(sb => sb.AppendFormat("[DefaultRouteInvoker] Processor threw {0} exception: {1}", e.GetType(), e.Message));
-            }
-
-            return null;
-        }
-
         private static Negotiator GetNegotiator(object routeResult, NancyContext context)
         {
             var negotiator = routeResult as Negotiator;