Fix regression in HttpMethod.GetHashCode()

A PR from last month changed how GetHashCode() works.  This ended up
breaking tests against the .NET Native build of System.Net.Http which
shares the same source code as CoreFx.   So, reverting the change in
GetHashCode() and porting additional ToF tests to GitHub.

Author: davidsh

src/System.Net.Http/src/System/Net/Http/HttpMethod.cs

@@ -106,7 +106,7 @@ public override bool Equals(object obj)
 
         public override int GetHashCode()
         {
-            return StringComparer.OrdinalIgnoreCase.GetHashCode(_method);
+            return _method.ToUpperInvariant().GetHashCode();
         }
 
         public override string ToString()

src/System.Net.Http/tests/FunctionalTests/HttpMethodTest.cs

@@ -0,0 +1,114 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.Net;
+using System.Net.Http;
+
+using Xunit;
+
+namespace System.Net.Http.Tests
+{
+    public class HttpMethodTest
+    {
+        [Fact]
+        public void StaticProperties_VerifyValues_PropertyNameMatchesHttpMethodName()
+        {
+            Assert.Equal("GET", HttpMethod.Get.Method);
+            Assert.Equal("PUT", HttpMethod.Put.Method);
+            Assert.Equal("POST", HttpMethod.Post.Method);
+            Assert.Equal("DELETE", HttpMethod.Delete.Method);
+            Assert.Equal("HEAD", HttpMethod.Head.Method);
+            Assert.Equal("OPTIONS", HttpMethod.Options.Method);
+            Assert.Equal("TRACE", HttpMethod.Trace.Method);
+        }
+
+        [Fact]
+        public void Ctor_ValidMethodToken_Success()
+        {
+            new HttpMethod("GET");
+            new HttpMethod("custom");
+
+            // Note that '!' is the first ASCII char after CTLs and '~' is the last character before DEL char.
+            new HttpMethod("validtoken!#$%&'*+-.0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz^_`|~");
+        }
+
+        [Fact]
+        public void Ctor_NullMethod_Exception()
+        {
+            Assert.Throws<ArgumentException>(() => { new HttpMethod(null); } );
+        }
+
+        // TODO: This should be a [Theory]
+        [Fact]
+        public void Ctor_SeparatorInMethod_Exception()
+        {
+            char[] separators = new char[] { '(', ')', '<', '>', '@', ',', ';', ':', '\\', '"', '/', '[', ']', 
+                '?', '=', '{', '}', ' ', '\t' };
+
+            for (int i = 0; i < separators.Length; i++)
+            {
+                Assert.Throws<FormatException>(() => { new HttpMethod("Get" + separators[i]); } );
+            }
+        }
+
+        [Fact]
+        public void Equals_DifferentComparisonMethodsForSameMethods_MethodsConsideredEqual()
+        {
+            // Positive test cases
+            Assert.True(new HttpMethod("GET") == HttpMethod.Get);
+            Assert.False(new HttpMethod("GET") != HttpMethod.Get);
+            Assert.True((new HttpMethod("GET")).Equals(HttpMethod.Get)); 
+
+            Assert.True(new HttpMethod("get") == HttpMethod.Get);
+            Assert.False(new HttpMethod("get") != HttpMethod.Get);
+            Assert.True((new HttpMethod("get")).Equals(HttpMethod.Get));
+        }
+
+        [Fact]
+        public void Equals_CompareWithMethodCastedToObject_ReturnsTrue()
+        {
+            object other = new HttpMethod("GET");
+            Assert.True(HttpMethod.Get.Equals(other));
+            Assert.False(HttpMethod.Get.Equals("GET"));
+        }
+
+        [Fact]
+        public void Equals_NullComparand_ReturnsFalse()
+        {
+            Assert.False(null == HttpMethod.Options);
+            Assert.False(HttpMethod.Trace == null);
+        }
+
+        [Fact]
+        public void GetHashCode_UseCustomStringMethod_SameAsStringHashCode()
+        {
+            string custom = "CUSTOM";
+            HttpMethod method = new HttpMethod(custom);
+            Assert.Equal(custom.GetHashCode(), method.GetHashCode());
+        }
+
+        [Fact]
+        public void GetHashCode_DifferentlyCasedMethod_SameHashCode()
+        {
+            string input = "GeT";
+            HttpMethod method = new HttpMethod(input);
+            Assert.Equal(HttpMethod.Get.GetHashCode(), method.GetHashCode());
+        }
+
+        [Fact]
+        public void ToString_UseCustomStringMethod_SameAsString()
+        {
+            string custom = "custom";
+            HttpMethod method = new HttpMethod(custom);
+            Assert.Equal(custom, method.ToString());
+        }
+
+        [Fact]
+        public void Method_AccessProperty_MatchesCtorString()
+        {
+            HttpMethod method = new HttpMethod("custom");
+            Assert.Equal("custom", method.Method);
+        }
+    }
+}

src/System.Net.Http/tests/FunctionalTests/System.Net.Http.Tests.csproj

@@ -20,6 +20,7 @@
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Windows_Release|AnyCPU' " />  
   <ItemGroup>
     <Compile Include="HttpClientHandlerTest.cs" />
+    <Compile Include="HttpMethodTest.cs" />
     <Compile Include="XunitTestAssemblyAtrributes.cs" />
   </ItemGroup>
   <ItemGroup>