Don't use OnSendingHeaders

WebApiThrottle.Tests/ThrottlingMiddlewareTests.cs

@@ -0,0 +1,78 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Microsoft.Owin;
+using Moq;
+using Xunit;
+
+namespace WebApiThrottle.Tests
+{
+    public class ThrottlingMiddlewareTests
+    {
+        private static IOwinContext CreateMockContext()
+        {
+            var context = Mock.Of<IOwinContext>();
+
+            Mock.Get(context).SetupGet(x => x.Request).Returns(Mock.Of<IOwinRequest>());
+            Mock.Get(context.Request).SetupAllProperties();
+            Mock.Get(context.Request).SetupGet(x => x.Headers).Returns(Mock.Of<IHeaderDictionary>());
+            Mock.Get(context.Request.Headers).SetupGet(x => x.Keys).Returns(new List<string>());
+            context.Request.RemoteIpAddress = "127.0.0.1";
+            Mock.Get(context.Request).SetupGet(x => x.Uri).Returns(new Uri($"http://{context.Request.RemoteIpAddress}"));
+
+            Mock.Get(context).SetupGet(x => x.Response).Returns(Mock.Of<IOwinResponse>());
+            Mock.Get(context.Response).SetupAllProperties();
+            Mock.Get(context.Response).SetupGet(x => x.Headers).Returns(Mock.Of<IHeaderDictionary>());
+            Mock.Get(context.Response.Headers).Setup(x => x.Add("Retry-After", It.IsAny<string[]>()));
+            context.Response.StatusCode = 200;
+
+            return context;
+        }
+
+        private static ThrottlingMiddleware CreateThrottlingMiddleware()
+        {
+            return new ThrottlingMiddleware(
+                new DummyMiddleware(null),
+                new ThrottlePolicy(1) {IpThrottling = true},
+                new PolicyMemoryCacheRepository(),
+                new MemoryCacheRepository(),
+                null,
+                null);
+        }
+
+
+        [Fact]
+        public void When_RateIsExceeded_Should_SetStatusCodeSoItsAvailableToMiddlewareFurtherDownTheStack()
+        {
+            var context = CreateMockContext();
+
+            var throttlingMiddleware = CreateThrottlingMiddleware();
+
+            throttlingMiddleware.Invoke(context).Wait();
+            throttlingMiddleware.Invoke(context).Wait();
+
+            Assert.Equal(429, context.Response.StatusCode);
+        }
+
+        [Fact]
+        public void When_RateIsNotExceeded_Should_NotSetStatusCode()
+        {
+            var context = CreateMockContext();
+
+            CreateThrottlingMiddleware().Invoke(context).Wait();
+
+            Assert.Equal(200, context.Response.StatusCode);
+        }
+    }
+
+    internal class DummyMiddleware : OwinMiddleware
+    {
+        public DummyMiddleware(OwinMiddleware next) : base(next)
+        {
+        }
+
+        public override async Task Invoke(IOwinContext context)
+        {
+        }
+    }
+}

WebApiThrottle.Tests/WebApiThrottle.Tests.csproj

@@ -30,6 +30,18 @@
     <WarningLevel>4</WarningLevel>
   </PropertyGroup>
   <ItemGroup>
+    <Reference Include="Castle.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=407dd0808d44fbdc, processorArchitecture=MSIL">
+      <HintPath>..\packages\Castle.Core.4.0.0\lib\net45\Castle.Core.dll</HintPath>
+    </Reference>
+    <Reference Include="Microsoft.Owin, Version=3.0.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
+      <HintPath>..\packages\Microsoft.Owin.3.0.1\lib\net45\Microsoft.Owin.dll</HintPath>
+    </Reference>
+    <Reference Include="Moq, Version=4.7.1.0, Culture=neutral, PublicKeyToken=69f491c39445e920, processorArchitecture=MSIL">
+      <HintPath>..\packages\Moq.4.7.1\lib\net45\Moq.dll</HintPath>
+    </Reference>
+    <Reference Include="Owin, Version=1.0.0.0, Culture=neutral, PublicKeyToken=f0ebd12fd5e55cc5, processorArchitecture=MSIL">
+      <HintPath>..\packages\Owin.1.0\lib\net40\Owin.dll</HintPath>
+    </Reference>
     <Reference Include="System" />
     <Reference Include="System.Core" />
     <Reference Include="System.Xml.Linq" />
@@ -58,6 +70,7 @@
   <ItemGroup>
     <Compile Include="IpAddressUtilTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="ThrottlingMiddlewareTests.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="packages.config" />

WebApiThrottle.Tests/packages.config

@@ -1,5 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
+  <package id="Castle.Core" version="4.0.0" targetFramework="net452" />
+  <package id="Microsoft.Owin" version="3.0.1" targetFramework="net452" />
+  <package id="Moq" version="4.7.1" targetFramework="net452" />
+  <package id="Owin" version="1.0" targetFramework="net452" />
   <package id="xunit" version="2.1.0" targetFramework="net452" />
   <package id="xunit.abstractions" version="2.0.0" targetFramework="net452" />
   <package id="xunit.assert" version="2.1.0" targetFramework="net452" />

WebApiThrottle/ThrottlingMiddleware.cs

@@ -196,13 +196,10 @@ public override async Task Invoke(IOwinContext context)
                             : "API calls quota exceeded! maximum admitted {0} per {1}.";
 
                         // break execution
-                        response.OnSendingHeaders(state =>
-                        {
-                            var resp = (OwinResponse)state;
-                            resp.Headers.Add("Retry-After", new string[] { core.RetryAfterFrom(throttleCounter.Timestamp, rateLimitPeriod) });
-                            resp.StatusCode = (int)QuotaExceededResponseCode;
-                            resp.ReasonPhrase = string.Format(message, rateLimit, rateLimitPeriod);
-                        }, response);
+                        response.StatusCode = (int)QuotaExceededResponseCode;
+                        response.ReasonPhrase = string.Format(message, rateLimit, rateLimitPeriod);
+
+                        response.Headers.Add("Retry-After", new[] { core.RetryAfterFrom(throttleCounter.Timestamp, rateLimitPeriod) });
 
                         return;
                     }