Added test that injects IHostingEnvironment

#221

test/Microsoft.AspNet.Hosting.Tests/Fakes/StartupWithHostingEnvironment.cs

@@ -0,0 +1,18 @@
+using System;
+using Microsoft.AspNet.Builder;
+
+namespace Microsoft.AspNet.Hosting.Tests.Fakes
+{
+    public class StartupWithHostingEnvironment
+    {
+        public StartupWithHostingEnvironment(IHostingEnvironment env)
+        {
+            env.EnvironmentName = "Changed";
+        }
+
+        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
+        {
+
+        }
+    }
+}

test/Microsoft.AspNet.Hosting.Tests/HostingEngineTests.cs

@@ -43,6 +43,21 @@ namespace Microsoft.AspNet.Hosting
             Assert.Equal(1, _startInstances[0].DisposeCalls);
         }
 
+        [Fact]
+        public void HostingEngineInjectsHostingEnvironment()
+        {
+            var engine = WebHost.CreateEngine()
+                .UseServer(this)
+                .UseStartup("Microsoft.AspNet.Hosting.Tests")
+                .UseEnvironment("WithHostingEnvironment");
+
+            using (var server = engine.Start())
+            {
+                var env = engine.ApplicationServices.GetRequiredService<IHostingEnvironment>();
+                Assert.Equal("Changed", env.EnvironmentName);
+            }
+        }
+
         [Fact]
         public void CanReplaceHostingFactory()
         {