Fix default parameter merging bugs, add MergedParameters to RestResponse

.github/workflows/pull-request.yml

@@ -37,7 +37,13 @@ jobs:
             9.0.x
             10.0.x
       - name: Run tests
-        run: dotnet test -c Debug -f ${{ matrix.dotnet }}
+        run: |
+          dotnet test test/RestSharp.Tests -c Debug -f ${{ matrix.dotnet }}
+          dotnet test test/RestSharp.Tests.Integrated -c Debug -f ${{ matrix.dotnet }}
+          dotnet test test/RestSharp.Tests.Serializers.Json -c Debug -f ${{ matrix.dotnet }}
+          dotnet test test/RestSharp.Tests.Serializers.Xml -c Debug -f ${{ matrix.dotnet }}
+          dotnet test test/RestSharp.Tests.Serializers.Csv -c Debug -f ${{ matrix.dotnet }}
+          dotnet test test/RestSharp.Tests.DependencyInjection -c Debug -f ${{ matrix.dotnet }}
       - name: Upload Test Results
         if: always()
         uses: actions/upload-artifact@v6
@@ -65,7 +71,13 @@ jobs:
             9.0.x
             10.0.x
       - name: Run tests
-        run: dotnet test -f ${{ matrix.dotnet }}
+        run: |
+          dotnet test test/RestSharp.Tests -f ${{ matrix.dotnet }}
+          dotnet test test/RestSharp.Tests.Integrated -f ${{ matrix.dotnet }}
+          dotnet test test/RestSharp.Tests.Serializers.Json -f ${{ matrix.dotnet }}
+          dotnet test test/RestSharp.Tests.Serializers.Xml -f ${{ matrix.dotnet }}
+          dotnet test test/RestSharp.Tests.Serializers.Csv -f ${{ matrix.dotnet }}
+          dotnet test test/RestSharp.Tests.DependencyInjection -f ${{ matrix.dotnet }}
       - name: Upload Test Results
         if: always()
         uses: actions/upload-artifact@v6

CLAUDE.md

@@ -0,0 +1,2 @@
+## MCP Servers Available
+- mem0: Use this AI memory for storing and retrieving long-term context as well as short-term context

RestSharp.slnx

@@ -0,0 +1,65 @@
+<Solution>
+  <Configurations>
+    <BuildType Name="Debug" />
+    <BuildType Name="Debug.Appveyor" />
+    <BuildType Name="Release" />
+    <Platform Name="Any CPU" />
+    <Platform Name="ARM" />
+    <Platform Name="Mixed Platforms" />
+    <Platform Name="x64" />
+    <Platform Name="x86" />
+  </Configurations>
+  <Folder Name="/Perf/">
+    <Project Path="benchmarks/RestSharp.Benchmarks/RestSharp.Benchmarks.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+  </Folder>
+  <Folder Name="/Serializers/">
+    <Project Path="src/RestSharp.Serializers.CsvHelper/RestSharp.Serializers.CsvHelper.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+    <Project Path="src/RestSharp.Serializers.NewtonsoftJson/RestSharp.Serializers.NewtonsoftJson.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+    <Project Path="src/RestSharp.Serializers.Xml/RestSharp.Serializers.Xml.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+  </Folder>
+  <Folder Name="/SourceGen/">
+    <Project Path="gen/SourceGenerator/SourceGenerator.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+  </Folder>
+  <Folder Name="/Tests/">
+    <Project Path="test/RestSharp.InteractiveTests/RestSharp.InteractiveTests.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+    <Project Path="test/RestSharp.Tests.DependencyInjection/RestSharp.Tests.DependencyInjection.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+    <Project Path="test/RestSharp.Tests.Integrated/RestSharp.Tests.Integrated.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+    <Project Path="test/RestSharp.Tests.Serializers.Csv/RestSharp.Tests.Serializers.Csv.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+    <Project Path="test/RestSharp.Tests.Serializers.Json/RestSharp.Tests.Serializers.Json.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+    <Project Path="test/RestSharp.Tests.Serializers.Xml/RestSharp.Tests.Serializers.Xml.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+    <Project Path="test/RestSharp.Tests.Shared/RestSharp.Tests.Shared.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+    <Project Path="test/RestSharp.Tests/RestSharp.Tests.csproj">
+      <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+    </Project>
+  </Folder>
+  <Project Path="src/RestSharp.Extensions.DependencyInjection/RestSharp.Extensions.DependencyInjection.csproj">
+    <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+  </Project>
+  <Project Path="src/RestSharp/RestSharp.csproj">
+    <BuildType Solution="Debug.Appveyor|*" Project="Debug" />
+  </Project>
+</Solution>

docs/docs/usage/response.md

@@ -28,6 +28,19 @@ Response object contains the following properties:
 | `ErrorException`         | `Exception?`                                        | Exception thrown when executing the request, if any.                                     |
 | `Version`                | `Version?`                                          | HTTP protocol version of the request.                                                    |
 | `RootElement`            | `string?`                                           | Root element of the serialized response content, only works if deserializer supports it. |
+| `MergedParameters`       | `ParametersCollection`                              | Combined view of request parameters and client default parameters at execution time.     |
+
+### Merged parameters
+
+The `MergedParameters` property provides a combined view of the request's own parameters and the client's [default parameters](request.md#request-headers) as they were at execution time. This is useful for logging or debugging the full set of parameters that were applied to a request, since `Request.Parameters` only contains the parameters added directly to the request.
+
+```csharp
+var response = await client.ExecuteAsync(request);
+
+foreach (var param in response.MergedParameters) {
+    Console.WriteLine($"{param.Name} = {param.Value} ({param.Type})");
+}
+```
 
 In addition, `RestResponse<T>` has one additional property:
 

src/RestSharp/Response/RestResponseBase.cs

@@ -132,6 +132,12 @@ protected RestResponseBase(RestRequest request) {
     /// </summary>
     public Version? Version { get; set; }
 
+    /// <summary>
+    /// Combined view of request parameters and client default parameters as they were at execution time.
+    /// Use this to inspect the full set of parameters that were applied to the request.
+    /// </summary>
+    public ParametersCollection MergedParameters { get; internal set; } = new RequestParameters();
+
     /// <summary>
     /// Root element of the serialized response content, only works if deserializer supports it 
     /// </summary>

src/RestSharp/RestClient.Async.cs

@@ -36,6 +36,7 @@ public async Task<RestResponse> ExecuteAsync(RestRequest request, CancellationTo
                 )
                 .ConfigureAwait(false)
             : GetErrorResponse(request, internalResponse.Exception, internalResponse.TimeoutToken);
+        response.MergedParameters = new RequestParameters(request.Parameters.Union(DefaultParameters));
         await OnAfterRequest(response, cancellationToken).ConfigureAwait(false);
 
         return Options.ThrowOnAnyError ? response.ThrowIfError() : response;

test/RestSharp.Tests.Integrated/DefaultParameterTests.cs

@@ -4,7 +4,8 @@
 namespace RestSharp.Tests.Integrated;
 
 public sealed class DefaultParameterTests(WireMockTestServer server) : IClassFixture<WireMockTestServer> {
-    readonly RequestBodyCapturer _capturer = server.ConfigureBodyCapturer(Method.Get, false);
+    readonly RequestBodyCapturer _capturer       = server.ConfigureBodyCapturer(Method.Get, false);
+    readonly RequestBodyCapturer _capturerOnPath = server.ConfigureBodyCapturer(Method.Get);
 
     [Fact]
     public async Task Should_add_default_and_request_query_get_parameters() {
@@ -48,4 +49,74 @@ public async Task Should_not_encode_pipe_character_when_encode_is_false() {
         var query = _capturer.RawUrl.Split('?')[1];
         query.Should().Contain("ids=in:001|116");
     }
+
+    [Fact]
+    public async Task Should_include_multiple_default_query_params_with_same_name() {
+        using var client = new RestClient(
+            new RestClientOptions(server.Url!) { AllowMultipleDefaultParametersWithSameName = true }
+        );
+        client.AddDefaultParameter("filter", "active", ParameterType.QueryString);
+        client.AddDefaultParameter("filter", "verified", ParameterType.QueryString);
+
+        var request = new RestRequest("capture");
+        await client.GetAsync(request);
+
+        var query = _capturerOnPath.Url!.Query;
+        query.Should().Contain("filter=active");
+        query.Should().Contain("filter=verified");
+    }
+
+    [Fact]
+    public async Task Should_include_default_query_params_in_BuildUriString_without_executing() {
+        using var client = new RestClient(server.Url!);
+        client.AddDefaultParameter("foo", "bar", ParameterType.QueryString);
+
+        var request = new RestRequest("resource");
+        var uri     = client.BuildUriString(request);
+
+        uri.Should().Contain("foo=bar");
+    }
+
+    [Fact]
+    public async Task Should_not_permanently_mutate_request_parameters_after_execute() {
+        using var client = new RestClient(server.Url!);
+        client.AddDefaultParameter("default_key", "default_val", ParameterType.QueryString);
+
+        var request      = new RestRequest("capture");
+        var paramsBefore = request.Parameters.Count;
+
+        await client.GetAsync(request);
+
+        // Request parameters should not have been mutated by the execution.
+        request.Parameters.Count.Should().Be(paramsBefore);
+
+        // Now replace the default parameter with a different value.
+        client.DefaultParameters.ReplaceParameter(new QueryParameter("default_key", "updated_val"));
+
+        await client.GetAsync(request);
+
+        // The second execution should use the updated default value, not the stale one.
+        var query = _capturerOnPath.Url!.Query;
+        query.Should().Contain("default_key=updated_val");
+        query.Should().NotContain("default_key=default_val");
+    }
+
+    [Fact]
+    public async Task Should_include_default_params_in_merged_parameters_on_response() {
+        using var client = new RestClient(server.Url!);
+        client.AddDefaultParameter("default_key", "default_val", ParameterType.QueryString);
+
+        var request  = new RestRequest("capture").AddQueryParameter("req_key", "req_val");
+        var response = await client.ExecuteAsync(request);
+
+        var defaultParam = response.MergedParameters
+            .FirstOrDefault(p => p.Name == "default_key" && p.Type == ParameterType.QueryString);
+        defaultParam.Should().NotBeNull();
+        defaultParam!.Value.Should().Be("default_val");
+
+        var requestParam = response.MergedParameters
+            .FirstOrDefault(p => p.Name == "req_key" && p.Type == ParameterType.QueryString);
+        requestParam.Should().NotBeNull();
+        requestParam!.Value.Should().Be("req_val");
+    }
 }

test/RestSharp.Tests.Integrated/HttpHeadersTests.cs

@@ -68,6 +68,25 @@ public async Task Should_sent_custom_UserAgent() {
         response.GetHeaderValue("Server").Should().Be("Kestrel");
     }
 
+    [Fact]
+    public async Task Default_headers_should_appear_in_response_merged_parameters() {
+        const string headerName  = "X-Custom-Default";
+        const string headerValue = "DefaultValue123";
+
+        _client.AddDefaultHeader(headerName, headerValue);
+
+        var request  = new RestRequest("/headers");
+        var response = await _client.ExecuteAsync(request);
+
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+
+        var param = response.MergedParameters
+            .FirstOrDefault(p => p.Name == headerName && p.Type == ParameterType.HttpHeader);
+
+        param.Should().NotBeNull();
+        param!.Value.Should().Be(headerValue);
+    }
+
     static void CheckHeader(RestResponse<TestServerResponse[]> response, Header header) {
         var h = FindHeader(response, header.Name);
         h.Should().NotBeNull();