Adds content validation methods

Added WithJsonContent asserter.
Added WithFormUrlEncoded asserter.

Closes #11

Author: dnperfors

src/HttpClientTestHelpers/HttpRequestMessageAsserter.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Net.Http;
+using System.Text.Json;
 
 namespace HttpClientTestHelpers
 {
@@ -269,6 +270,30 @@ public HttpRequestMessageAsserter WithContent(string pattern)
             return With(x => x.HasContent(pattern), $"content '{pattern}'");
         }
 
+        /// <summary>
+        /// Asserts wheter requests are made with specific json content.
+        /// </summary>
+        /// <param name="jsonObject">The object representation of the expected request content.</param>
+        /// <returns>The <seealso cref="HttpRequestMessageAsserter"/> for further assertions.</returns>
+        public HttpRequestMessageAsserter WithJsonContent(object? jsonObject)
+        {
+            var jsonString = JsonSerializer.Serialize(jsonObject);
+            return With(x => x.HasContent(jsonString) && x.HasContentHeader("Content-Type", "application/json*"), $"json content '{jsonString}'");
+        }
+
+        public HttpRequestMessageAsserter WithFormUrlEncodedContent(IEnumerable<KeyValuePair<string, string>> nameValueCollection)
+        {
+            if (nameValueCollection == null)
+            {
+                throw new ArgumentNullException(nameof(nameValueCollection));
+            }
+
+            using var content = new FormUrlEncodedContent(nameValueCollection);
+            var contentString = content.ReadAsStringAsync().Result;
+
+            return With(x => x.HasContent(contentString) && x.HasContentHeader("Content-Type", "application/x-www-form-urlencoded*"), $"form url encoded content '{contentString}'");
+        }
+
         /// <summary>
         /// Asserts that a specific amount of requests were made.
         /// </summary>

test/HttpClientTestHelpers.IntegrationTests/AssertingRequests.cs

@@ -161,6 +161,17 @@ public async Task AssertingContent()
             Assert.Throws<HttpRequestMessageAssertionException>(() => testHandler.ShouldHaveMadeRequests().WithContent("my"));
         }
 
+        [Fact]
+        public async Task AssertJsonContent()
+        {
+            var testHandler = new TestableHttpMessageHandler();
+            var client = new HttpClient(testHandler);
+
+            _ = await client.PostAsync("https://httpbin.org/post", new StringContent("{}", Encoding.UTF8, "application/json"));
+
+            testHandler.ShouldHaveMadeRequests().WithJsonContent(new { });
+        }
+
         [Fact]
         public async Task CustomAssertions()
         {

test/HttpClientTestHelpers.Tests/HttpRequestMessageAsserterTests.cs

@@ -1,7 +1,9 @@
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using System.Net;
 using System.Net.Http;
+using System.Net.Http.Headers;
 using System.Text;
 
 using Xunit;
@@ -605,6 +607,107 @@ public void WithContent_RequestWithMatchingContent_ReturnsHttpRequestMessageAsse
             Assert.IsType<HttpRequestMessageAsserter>(result);
         }
 
+        [Fact]
+        public void WithJsonContent_RequestWithMatchingContent_ReturnsHttpRequestMessageAsserter()
+        {
+            var request = new HttpRequestMessage
+            {
+                Content = new StringContent("null", Encoding.UTF8, "application/json")
+            };
+            var sut = new HttpRequestMessageAsserter(new[] { request });
+
+            var result = sut.WithJsonContent(null);
+
+            Assert.NotNull(result);
+            Assert.IsType<HttpRequestMessageAsserter>(result);
+        }
+
+        [Fact]
+        public void WithJsonContent_RequestWithDifferentContent_ThrowsHttpRequestMessageAssertionExceptionWithSpecificMessage()
+        {
+            var request = new HttpRequestMessage
+            {
+                Content = new StringContent("{}", Encoding.UTF8, "application/json")
+            };
+            var sut = new HttpRequestMessageAsserter(new[] { request });
+
+            var exception = Assert.Throws<HttpRequestMessageAssertionException>(() => sut.WithJsonContent(null));
+            Assert.Equal("Expected at least one request to be made with json content 'null', but no requests were made.", exception.Message);
+        }
+
+        [Fact]
+        public void WithJsonContent_RequestWithDifferentContentType_ThrowsHttpRequestMessageAssertionExceptionWithSpecificMessage()
+        {
+            var request = new HttpRequestMessage
+            {
+                Content = new StringContent("null", Encoding.UTF8)
+            };
+            var sut = new HttpRequestMessageAsserter(new[] { request });
+
+            var exception = Assert.Throws<HttpRequestMessageAssertionException>(() => sut.WithJsonContent(null));
+            Assert.Equal("Expected at least one request to be made with json content 'null', but no requests were made.", exception.Message);
+        }
+
+#nullable disable
+        [Fact]
+        public void WithFormUrlEncodedContent_NullNameValueCollection_ThrowsArgumentNullException()
+        {
+            var request = new HttpRequestMessage
+            {
+                Content = new FormUrlEncodedContent(Enumerable.Empty<KeyValuePair<string, string>>())
+            };
+            var sut = new HttpRequestMessageAsserter(new[] { request });
+
+            var exception = Assert.Throws<ArgumentNullException>(() => sut.WithFormUrlEncodedContent(null));
+
+            Assert.Equal("nameValueCollection", exception.ParamName);
+        }
+#nullable restore
+
+        [Fact]
+        public void WithFormUrlEncodedContent_RequestWithMatchingContent_ReturnsHttpRequestMessageAsserter()
+        {
+            var request = new HttpRequestMessage
+            {
+                Content = new FormUrlEncodedContent(Enumerable.Empty<KeyValuePair<string, string>>())
+            };
+            var sut = new HttpRequestMessageAsserter(new[] { request });
+
+            var result = sut.WithFormUrlEncodedContent(Enumerable.Empty<KeyValuePair<string, string>>());
+
+            Assert.NotNull(result);
+            Assert.IsType<HttpRequestMessageAsserter>(result);
+        }
+
+        [Fact]
+        public void WithFormUrlEncodedContent_RequestWithNotMatchingContent_ThrowsHttpRequestMessageAssertionExceptionWithSpecificMessage()
+        {
+            var request = new HttpRequestMessage
+            {
+                Content = new FormUrlEncodedContent(Enumerable.Empty<KeyValuePair<string, string>>())
+            };
+            var sut = new HttpRequestMessageAsserter(new[] { request });
+
+            var exception = Assert.Throws<HttpRequestMessageAssertionException>(() => sut.WithFormUrlEncodedContent(new Dictionary<string, string> { ["username"] = "alice" }));
+
+            Assert.Equal("Expected at least one request to be made with form url encoded content 'username=alice', but no requests were made.", exception.Message);
+        }
+
+        [Fact]
+        public void WithFormUrlEncodedContent_RequestWithNotMatchingContentType_ThrowsHttpRequestMessageAssertionExceptionWithSpecificMessage()
+        {
+            var request = new HttpRequestMessage
+            {
+                Content = new FormUrlEncodedContent(new Dictionary<string, string> { ["username"] = "alice" })
+            };
+            request.Content.Headers.ContentType = new MediaTypeHeaderValue("plain/text");
+            var sut = new HttpRequestMessageAsserter(new[] { request });
+
+            var exception = Assert.Throws<HttpRequestMessageAssertionException>(() => sut.WithFormUrlEncodedContent(new Dictionary<string, string> { ["username"] = "alice" }));
+
+            Assert.Equal("Expected at least one request to be made with form url encoded content 'username=alice', but no requests were made.", exception.Message);
+        }
+
         [Fact]
         public void Times_ValueLessThan0_ThrowsArgumentException()
         {