Implement SendFormUrlEncoded method for application/x-www-form-urlencoded form data (#27)

In #9, the `SendForm` extension method was changed from sending a `application/x-www-form-urlencoded` request to sending one as `multipart/form-data` instead. This is a breaking change in some cases if sending to an endpoint that doesn't expect form data to come in with `multipart/form-data` encoding (OIDC access token requests for example, see opserver/Opserver#426).

This PR re-adds the old behaviour as a new extension method so consuming libraries don't need to add it back themselves.

I expect `application/x-www-form-urlencoded` is the more common media type that consumers will want (when size limitations or file uploads aren't a concern), but I didn't want to revert `SendForm` back to its original behaviour to avoid breaking dependent projects again.

I could also obsolete `SendForm` and provide `SendMultipartForm` / `SendFormUrlEncoded` but I don't think it's important enough to inconvenience consumers with changing their code (and getting build errors using `TreatWarningsAsErrors`).

Author: dionrhys

src/StackExchange.Utils.Http/Extensions.Send.cs

@@ -24,7 +24,8 @@ public static IRequestBuilder SendContent(this IRequestBuilder builder, HttpCont
         }
 
         /// <summary>
-        /// Adds a <see cref="NameValueCollection"/> as the body for this request.
+        /// Adds a <see cref="NameValueCollection"/> as the body for this request, with a content type of
+        /// <c>multipart/form-data</c>.
         /// </summary>
         /// <param name="builder">The builder we're working on.</param>
         /// <param name="form">The <see cref="NameValueCollection"/> (e.g. FormCollection) to use.</param>
@@ -38,7 +39,17 @@ public static IRequestBuilder SendForm(this IRequestBuilder builder, NameValueCo
             }
             return SendContent(builder, content);
         }
-            
+
+        /// <summary>
+        /// Adds a <see cref="NameValueCollection"/> as the body for this request, with a content type of
+        /// <c>application/x-www-form-urlencoded</c>.
+        /// </summary>
+        /// <param name="builder">The builder we're working on.</param>
+        /// <param name="form">The <see cref="NameValueCollection"/> (e.g. FormCollection) to use.</param>
+        /// <returns>The request builder for chaining.</returns>
+        public static IRequestBuilder SendFormUrlEncoded(this IRequestBuilder builder, NameValueCollection form) =>
+            SendContent(builder, new FormUrlEncodedContent(form.AllKeys.ToDictionary(k => k, v => form[v])));
+
         /// <summary>
         /// Adds raw HTML content as the body for this request.
         /// </summary>

tests/StackExchange.Utils.Tests/HttpTests.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Collections.Specialized;
 using System.Net;
 using System.Net.Http;
 using System.Threading.Tasks;
@@ -142,7 +143,7 @@ public async Task Timeouts()
         public async Task AddHeaderWithoutValidation()
         {
             var result = await Http.Request("https://httpbin.org/bearer")
-                                   .AddHeaderWithoutValidation("Authorization","abcd")
+                                   .AddHeaderWithoutValidation("Authorization", "abcd")
                                    .ExpectJson<HttpBinResponse>()
                                    .GetAsync();
             Assert.True(result.RawRequest.Headers.Contains("Authorization"));
@@ -162,7 +163,7 @@ public async Task AddHeaders()
                 .ExpectJson<HttpBinResponse>()
                 .GetAsync();
 
-            Assert.Equal(HttpStatusCode.OK,result.StatusCode);
+            Assert.Equal(HttpStatusCode.OK, result.StatusCode);
             Assert.Equal("Test", result.Data.Headers["Custom"]);
             // Content-Type should be present because we're sending a body up
             Assert.StartsWith("application/json", result.Data.Headers["Content-Type"]);
@@ -181,7 +182,7 @@ public async Task TestAddHeadersWhereClientAddsHeaderBeforeContent()
                 .ExpectJson<HttpBinResponse>()
                 .GetAsync();
 
-            Assert.Equal(HttpStatusCode.OK,result.StatusCode);
+            Assert.Equal(HttpStatusCode.OK, result.StatusCode);
             Assert.Equal("Test", result.Data.Headers["Custom"]);
             Assert.Equal("application/json; charset=utf-8", result.Data.Headers["Content-Type"]);
         }
@@ -198,7 +199,7 @@ public async Task TestAddHeadersWhereClientAddsHeaderAndNoContent()
                 .ExpectJson<HttpBinResponse>()
                 .GetAsync();
 
-            Assert.Equal(HttpStatusCode.OK,result.StatusCode);
+            Assert.Equal(HttpStatusCode.OK, result.StatusCode);
             Assert.Equal("Test", result.Data.Headers["Custom"]);
             // Content-Type is NOT sent when there's no body - this is correct behavior
             Assert.DoesNotContain("Content-Type", result.Data.Headers.Keys);
@@ -221,14 +222,60 @@ public async Task PatchRequest()
             Assert.Equal(Http.DefaultSettings.UserAgent, result.Data.Headers["User-Agent"]);
         }
 
+        [Fact]
+        public async Task SendFormUsesMultipartFormData()
+        {
+            string expectedFormKey = "key";
+            string expectedFormValue = "value";
+            var form = new NameValueCollection
+            {
+                [expectedFormKey] = expectedFormValue
+            };
+            var result = await Http.Request("https://httpbin.org/post")
+                .SendForm(form)
+                .ExpectJson<HttpBinResponse>()
+                .PostAsync();
+
+            Assert.NotNull(result);
+            Assert.True(result.Success);
+            Assert.Equal(HttpStatusCode.OK, result.StatusCode);
+            var actualContentType = Assert.Contains("Content-Type", (IDictionary<string, string>)result.Data.Headers);
+            Assert.StartsWith("multipart/form-data;", actualContentType);
+            var actualFormValue = Assert.Contains(expectedFormKey, (IDictionary<string, string>)result.Data.Form);
+            Assert.Equal(expectedFormValue, actualFormValue);
+        }
+
+        [Fact]
+        public async Task SendFormUrlEncodedUsesFormDataUrlEncoded()
+        {
+            string expectedFormKey = "key";
+            string expectedFormValue = "value";
+            var form = new NameValueCollection
+            {
+                [expectedFormKey] = expectedFormValue
+            };
+            var result = await Http.Request("https://httpbin.org/post")
+                .SendFormUrlEncoded(form)
+                .ExpectJson<HttpBinResponse>()
+                .PostAsync();
+
+            Assert.NotNull(result);
+            Assert.True(result.Success);
+            Assert.Equal(HttpStatusCode.OK, result.StatusCode);
+            var actualContentType = Assert.Contains("Content-Type", (IDictionary<string, string>)result.Data.Headers);
+            Assert.Equal("application/x-www-form-urlencoded", actualContentType);
+            var actualFormValue = Assert.Contains(expectedFormKey, (IDictionary<string, string>)result.Data.Form);
+            Assert.Equal(expectedFormValue, actualFormValue);
+        }
+
         [Fact]
         public async Task LargePost()
         {
             // 5MB string
             var myString = new string('*', 1048576 * 5);
 
             var form = new System.Collections.Specialized.NameValueCollection
-            {                
+            {
                 ["requestsJson"] = myString
             };