Attempt to start exercising the various paths of OnException.

Not working.  ExceptionContext is the big roadblock. Can't seem to mock that guy.

Author: walterpinson

test/Test.Unit.Infrastructure.WebApi/Exceptions/NoteBookExceptionFilterTester.cs

@@ -1,6 +1,9 @@
 namespace Test.Unit.Infrastructure.WebApi.Exceptions
 {
+    using System;
     using CompanyName.Notebook.NoteTaking.Infrastructure.WebApi.Exceptions;
+    using Microsoft.AspNetCore.Http;
+    using Microsoft.AspNetCore.Mvc.Filters;
     using Microsoft.Extensions.Logging;
     using NSubstitute;
     using NUnit.Framework;
@@ -21,5 +24,34 @@ public void CanConstructNoteBookExceptionFilter()
             Assert.That(subjectUnderTest, Is.Not.Null);
             Assert.That(subjectUnderTest, Is.TypeOf(typeof(NoteBookExceptionFilter)));
         }
+
+        public void OnExceptionHandlesUnauthorized()
+        {
+            // ARRANGE
+            var expectedException = Substitute.For<UnauthorizedAccessException>();
+            var expectedHttpContext = Substitute.For<HttpContext>();
+            var expectedHttpResponse = Substitute.For<HttpResponse>();
+            // var thing = Substitute.For<ExceptionContextCatchBlock>();
+            var context = Substitute.For<ExceptionContext>(expectedException, null);
+
+            context.Exception.Returns(expectedException);
+            expectedException.GetType().Returns(typeof(UnauthorizedAccessException));
+            context.HttpContext.Returns(expectedHttpContext);
+            expectedHttpContext.Response.Returns(expectedHttpResponse);
+
+            var logger = Substitute.For<ILogger<NoteBookExceptionFilter>>();
+            var subjectUnderTest = new NoteBookExceptionFilter(logger);
+
+            // ACT
+            subjectUnderTest.OnException(context);
+
+            // ASSERT
+            var temp1 = context.Received(2).Exception;
+            expectedException.Received(1).GetType();
+            logger.Received(1).LogError(0, expectedException, "Unauthorized Access");
+            var temp2 = context.Received(1).HttpContext;
+            var temp3 = expectedHttpContext.Received(1).Response;
+            expectedHttpResponse.ReceivedWithAnyArgs(1).WriteAsync(Arg.Any<string>());
+        }
     }
 }