Add NotFoundException for 404 status

Octokit.Tests/Http/ConnectionTests.cs

@@ -231,6 +231,28 @@ namespace Octokit.Tests.Http
                 Assert.Equal("http://developer.github.com/v3", exception.ApiError.DocumentationUrl);
             }
 
+            [Fact]
+            public async Task ThrowsNotFoundExceptionForFileNotFoundResponse()
+            {
+                var httpClient = Substitute.For<IHttpClient>();
+                IResponse<string> response = new ApiResponse<string>
+                {
+                    StatusCode = HttpStatusCode.NotFound,
+                    Body = "GONE BYE BYE!"
+                };
+                httpClient.Send<string>(Args.Request).Returns(Task.FromResult(response));
+                var connection = new Connection("Test Runner User Agent",
+                    ExampleUri,
+                    Substitute.For<ICredentialStore>(),
+                    httpClient,
+                    Substitute.For<IJsonSerializer>());
+
+                var exception = await AssertEx.Throws<NotFoundException>(
+                    async () => await connection.GetAsync<string>(new Uri("/endpoint", UriKind.Relative)));
+
+                Assert.Equal("GONE BYE BYE!", exception.Message);
+            }
+
             [Fact]
             public async Task ThrowsForbiddenExceptionForUnknownForbiddenResponse()
             {

Octokit/Exceptions/NotFoundException.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+using System.Net;
+using System.Runtime.Serialization;
+
+namespace Octokit
+{
+#if !NETFX_CORE
+    [Serializable]
+#endif
+    [SuppressMessage("Microsoft.Design", "CA1032:ImplementStandardExceptionConstructors",
+        Justification = "These exceptions are specific to the GitHub API and not general purpose exceptions")]
+    public class NotFoundException : ApiException
+    {
+        public NotFoundException(IResponse response) : this(response, null)
+        {
+        }
+
+        public NotFoundException(IResponse response, Exception innerException) : base(response, innerException)
+        {
+            Debug.Assert(response != null && response.StatusCode == HttpStatusCode.NotFound,
+                "NotFoundException created with wrong status code");
+        }
+
+        #if !NETFX_CORE
+        protected NotFoundException(SerializationInfo info, StreamingContext context)
+            : base(info, context)
+        {
+        }
+#endif
+    }
+}

Octokit/Http/Connection.cs

@@ -244,6 +244,11 @@ namespace Octokit
                 throw exceptionFunc(response);
             }
 
+            if ((int)response.StatusCode == 404)
+            {
+                throw new NotFoundException(response);
+            }
+
             if ((int)response.StatusCode >= 400)
             {
                 throw new ApiException(response);

Octokit/Octokit.csproj

@@ -82,6 +82,7 @@
       <Link>Properties\SolutionInfo.cs</Link>
     </Compile>
     <Compile Include="Clients\IssuesClient.cs" />
+    <Compile Include="Exceptions\NotFoundException.cs" />
     <Compile Include="IIssuesClient.cs" />
     <Compile Include="Models\Issue.cs" />
     <Compile Include="Models\IssueRequest.cs" />

Octokit/OctokitRT.csproj

@@ -122,6 +122,7 @@
     <Compile Include="Exceptions\ApiException.cs" />
     <Compile Include="Exceptions\ApiValidationException.cs" />
     <Compile Include="Exceptions\AuthorizationException.cs" />
+    <Compile Include="Exceptions\NotFoundException.cs" />
     <Compile Include="Exceptions\TwoFactorChallengeFailedException.cs" />
     <Compile Include="Exceptions\TwoFactorRequiredException.cs" />
     <Compile Include="Helpers\ApiUrls.cs" />