Add client conformance tests (#1102)

Co-authored-by: Stephen Halter <halter73@gmail.com>

tests/ModelContextProtocol.AspNetCore.Tests/ClientConformanceTests.cs

@@ -0,0 +1,99 @@
+using System.Diagnostics;
+using System.Text;
+using ModelContextProtocol.Tests.Utils;
+
+namespace ModelContextProtocol.ConformanceTests;
+
+/// <summary>
+/// Runs the official MCP conformance tests against the ConformanceClient.
+/// This test runs the Node.js-based conformance test suite for the client
+/// and reports the results.
+/// </summary>
+public class ClientConformanceTests //: IAsyncLifetime
+{
+    private readonly ITestOutputHelper _output;
+
+    // Public static property required for SkipUnless attribute
+    public static bool IsNpxInstalled => NodeHelpers.IsNpxInstalled();
+
+    public ClientConformanceTests(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
+    [Theory(Skip = "npx is not installed. Skipping client conformance tests.", SkipUnless = nameof(IsNpxInstalled))]
+    [InlineData("initialize")]
+    [InlineData("tools_call")]
+    [InlineData("auth/metadata-default")]
+    [InlineData("auth/metadata-var1")]
+    [InlineData("auth/metadata-var2")]
+    [InlineData("auth/metadata-var3")]
+    [InlineData("auth/basic-cimd")]
+    // [InlineData("auth/2025-03-26-oauth-metadata-backcompat")]
+    // [InlineData("auth/2025-03-26-oauth-endpoint-fallback")]
+    [InlineData("auth/scope-from-www-authenticate")]
+    [InlineData("auth/scope-from-scopes-supported")]
+    [InlineData("auth/scope-omitted-when-undefined")]
+    [InlineData("auth/scope-step-up")]
+    public async Task RunConformanceTest(string scenario)
+    {
+        // Run the conformance test suite
+        var result = await RunClientConformanceScenario(scenario);
+
+        // Report the results
+        Assert.True(result.Success,
+            $"Conformance test failed.\n\nStdout:\n{result.Output}\n\nStderr:\n{result.Error}");
+    }
+
+    private async Task<(bool Success, string Output, string Error)> RunClientConformanceScenario(string scenario)
+    {
+        // Construct an absolute path to the conformance client executable
+        var exeSuffix = OperatingSystem.IsWindows() ? ".exe" : "";
+        var conformanceClientPath = Path.GetFullPath($"./ModelContextProtocol.ConformanceClient{exeSuffix}");
+        // Replace AspNetCore.Tests with ConformanceClient in the path
+        conformanceClientPath = conformanceClientPath.Replace("AspNetCore.Tests", "ConformanceClient");
+
+        if (!File.Exists(conformanceClientPath))
+        {
+            throw new FileNotFoundException(
+                $"ConformanceClient executable not found at: {conformanceClientPath}");
+        }
+
+        var startInfo = NodeHelpers.NpxStartInfo($"-y @modelcontextprotocol/conformance client --scenario {scenario} --command \"{conformanceClientPath} {scenario}\"");
+
+        var outputBuilder = new StringBuilder();
+        var errorBuilder = new StringBuilder();
+
+        var process = new Process { StartInfo = startInfo };
+
+        process.OutputDataReceived += (sender, e) =>
+        {
+            if (e.Data != null)
+            {
+                _output.WriteLine(e.Data);
+                outputBuilder.AppendLine(e.Data);
+            }
+        };
+
+        process.ErrorDataReceived += (sender, e) =>
+        {
+            if (e.Data != null)
+            {
+                _output.WriteLine(e.Data);
+                errorBuilder.AppendLine(e.Data);
+            }
+        };
+
+        process.Start();
+        process.BeginOutputReadLine();
+        process.BeginErrorReadLine();
+
+        await process.WaitForExitAsync();
+
+        return (
+            Success: process.ExitCode == 0,
+            Output: outputBuilder.ToString(),
+            Error: errorBuilder.ToString()
+        );
+    }
+}