Add test for user agent header

Author: alexeyzimarev

test/RestSharp.Tests.Integrated/HttpHeadersTests.cs

@@ -1,7 +1,9 @@
 namespace RestSharp.Tests.Integrated;
 
 public sealed class HttpHeadersTests(WireMockTestServer server) : IClassFixture<WireMockTestServer>, IDisposable {
-    readonly RestClient _client = new(new RestClientOptions(server.Url!) { ThrowOnAnyError = true });
+    const string UserAgent = "RestSharp/test";
+
+    readonly RestClient _client = new(new RestClientOptions(server.Url!) { ThrowOnAnyError = true, UserAgent = UserAgent });
 
     [Fact]
     public async Task Ensure_headers_correctly_set_in_the_interceptor() {
@@ -17,7 +19,7 @@ public async Task Ensure_headers_correctly_set_in_the_interceptor() {
 
         // Assert
         response.StatusCode.Should().Be(HttpStatusCode.OK);
-        var header = response.Data!.First(x => x.Name == headerName);
+        var header = FindHeader(response, headerName);
         header.Should().NotBeNull();
         header.Value.Should().Be(headerValue);
     }
@@ -40,7 +42,7 @@ public async Task Ensure_headers_correctly_set_in_the_hook() {
         // Assert
         response.StatusCode.Should().Be(HttpStatusCode.OK);
         response.Data.Should().NotBeNull();
-        var header = response.Data!.First(x => x.Name == headerName);
+        var header = FindHeader(response, headerName);
         header.Should().NotBeNull();
         header.Value.Should().Be(headerValue);
     }
@@ -56,17 +58,28 @@ public async Task Should_use_both_default_and_request_headers() {
             .AddHeader(requestHeader.Name, requestHeader.Value);
 
         var response = await _client.ExecuteAsync<TestServerResponse[]>(request);
-        CheckHeader(defaultHeader);
-        CheckHeader(requestHeader);
-        return;
-
-        void CheckHeader(Header header) {
-            var h = response.Data!.First(x => x.Name == header.Name);
-            h.Should().NotBeNull();
-            h.Value.Should().Be(header.Value);
-        }
+        CheckHeader(response, defaultHeader);
+        CheckHeader(response, requestHeader);
     }
 
+    [Fact]
+    public async Task Should_sent_custom_UserAgent() {
+        var request  = new RestRequest("/headers");
+        var response = await _client.ExecuteAsync<TestServerResponse[]>(request);
+        var h = FindHeader(response, "User-Agent");
+        h.Should().NotBeNull();
+        h.Value.Should().Be(UserAgent);
+    }
+
+    static void CheckHeader(RestResponse<TestServerResponse[]> response, Header header) {
+        var h = FindHeader(response, header.Name);
+        h.Should().NotBeNull();
+        h.Value.Should().Be(header.Value);
+    }
+
+    static TestServerResponse FindHeader(RestResponse<TestServerResponse[]> response, string headerName)
+        => response.Data!.First(x => x.Name == headerName);
+
     record Header(string Name, string Value);
 
     class HeaderInterceptor(string headerName, string headerValue) : Interceptors.Interceptor {

test/RestSharp.Tests/RestClientTests.cs

@@ -130,9 +130,7 @@ public void ConfigureDefaultParameters_sets_user_agent_new_httpClient_instance()
         //assert
         Assert.Single(
             restClient.DefaultParameters,
-            parameter => parameter.Type == ParameterType.HttpHeader &&
-                parameter.Name == KnownHeaders.UserAgent &&
-                parameter.Value is string valueAsString &&
+            parameter => parameter is { Type: ParameterType.HttpHeader, Name: KnownHeaders.UserAgent, Value: string valueAsString } &&
                 valueAsString == clientOptions.UserAgent
         );
 
@@ -151,9 +149,7 @@ public void ConfigureDefaultParameters_sets_user_agent_given_httpClient_instance
         //assert
         Assert.Single(
             restClient.DefaultParameters,
-            parameter => parameter.Type == ParameterType.HttpHeader &&
-                parameter.Name == KnownHeaders.UserAgent &&
-                parameter.Value is string valueAsString &&
+            parameter => parameter is { Type: ParameterType.HttpHeader, Name: KnownHeaders.UserAgent, Value: string valueAsString } &&
                 valueAsString == clientOptions.UserAgent
         );