Default draft protocol support: sessionless + handshake-less (SEP-2575 + SEP-2567) (#1610)

tests/ModelContextProtocol.Tests/Protocol/DiscoverResultCacheableTests.cs

@@ -0,0 +1,125 @@
+using ModelContextProtocol.Protocol;
+using System.Text.Json;
+using System.Text.Json.Nodes;
+
+namespace ModelContextProtocol.Tests.Protocol;
+
+/// <summary>
+/// Targeted tests for the SEP-2549 caching hints (<c>ttlMs</c> and <c>cacheScope</c>) on
+/// <see cref="DiscoverResult"/>. Spec PR #2855 promotes both fields to required on the discover
+/// response. <see cref="DiscoverResult"/> has <c>required</c> CLR properties for
+/// <see cref="DiscoverResult.SupportedVersions"/>, <see cref="DiscoverResult.Capabilities"/>, and
+/// <see cref="DiscoverResult.ServerInfo"/>, which prevents reuse of the parameterized
+/// <see cref="CacheableResultTests"/> helper (it instantiates via reflection). This file covers the
+/// same property-shape assertions for <see cref="DiscoverResult"/>.
+/// </summary>
+public static class DiscoverResultCacheableTests
+{
+    private static DiscoverResult NewDiscoverResult() => new()
+    {
+        SupportedVersions = ["2025-11-25", McpSession.DraftProtocolVersion],
+        Capabilities = new ServerCapabilities(),
+        ServerInfo = new Implementation { Name = "test-server", Version = "1.0" },
+    };
+
+    [Fact]
+    public static void DiscoverResult_SerializesTtlMsAsIntegerMilliseconds()
+    {
+        var result = NewDiscoverResult();
+        result.TimeToLive = TimeSpan.FromMilliseconds(300_000);
+        result.CacheScope = CacheScope.Public;
+
+        string json = JsonSerializer.Serialize(result, McpJsonUtilities.DefaultOptions);
+        var node = JsonNode.Parse(json)!.AsObject();
+
+        Assert.True(node.ContainsKey("ttlMs"));
+        Assert.Equal(JsonValueKind.Number, node["ttlMs"]!.GetValueKind());
+        Assert.Equal(300_000, node["ttlMs"]!.GetValue<long>());
+        Assert.Equal("public", node["cacheScope"]!.GetValue<string>());
+
+        var deserialized = JsonSerializer.Deserialize<DiscoverResult>(json, McpJsonUtilities.DefaultOptions)!;
+        Assert.Equal(TimeSpan.FromMilliseconds(300_000), deserialized.TimeToLive);
+        Assert.Equal(CacheScope.Public, deserialized.CacheScope);
+    }
+
+    [Fact]
+    public static void DiscoverResult_PrivateScope_RoundTrips()
+    {
+        var result = NewDiscoverResult();
+        result.TimeToLive = TimeSpan.Zero;
+        result.CacheScope = CacheScope.Private;
+
+        string json = JsonSerializer.Serialize(result, McpJsonUtilities.DefaultOptions);
+        var node = JsonNode.Parse(json)!.AsObject();
+
+        Assert.True(node.ContainsKey("ttlMs"));
+        Assert.Equal(0, node["ttlMs"]!.GetValue<long>());
+        Assert.Equal("private", node["cacheScope"]!.GetValue<string>());
+
+        var deserialized = JsonSerializer.Deserialize<DiscoverResult>(json, McpJsonUtilities.DefaultOptions)!;
+        Assert.Equal(TimeSpan.Zero, deserialized.TimeToLive);
+        Assert.Equal(CacheScope.Private, deserialized.CacheScope);
+    }
+
+    [Fact]
+    public static void DiscoverResult_OmitsCachingHints_WhenUnset()
+    {
+        var result = NewDiscoverResult();
+
+        string json = JsonSerializer.Serialize(result, McpJsonUtilities.DefaultOptions);
+        var node = JsonNode.Parse(json)!.AsObject();
+
+        // Backward compatibility: servers that do not set the hints must not emit them.
+        Assert.False(node.ContainsKey("ttlMs"));
+        Assert.False(node.ContainsKey("cacheScope"));
+
+        var deserialized = JsonSerializer.Deserialize<DiscoverResult>(json, McpJsonUtilities.DefaultOptions)!;
+        Assert.Null(deserialized.TimeToLive);
+        Assert.Null(deserialized.CacheScope);
+    }
+
+    [Fact]
+    public static void DiscoverResult_DeserializesMissingHints_AsNull()
+    {
+        // A response from a pre-PR-#2855 server may omit both fields. Deserialization must succeed
+        // and surface them as null so callers can apply their own defaults.
+        string json =
+            """
+            {
+              "supportedVersions": ["2025-11-25"],
+              "capabilities": {},
+              "serverInfo": {"name": "x", "version": "1"}
+            }
+            """;
+
+        var deserialized = JsonSerializer.Deserialize<DiscoverResult>(json, McpJsonUtilities.DefaultOptions)!;
+        Assert.Null(deserialized.TimeToLive);
+        Assert.Null(deserialized.CacheScope);
+    }
+
+    [Fact]
+    public static void DiscoverResult_DeserializesUnknownCacheScope_AsNull()
+    {
+        // A future or unknown cacheScope string must not break deserialization of the entire result.
+        string json =
+            """
+            {
+              "supportedVersions": ["2025-11-25"],
+              "capabilities": {},
+              "serverInfo": {"name": "x", "version": "1"},
+              "cacheScope": "shared"
+            }
+            """;
+
+        var deserialized = JsonSerializer.Deserialize<DiscoverResult>(json, McpJsonUtilities.DefaultOptions)!;
+        Assert.Null(deserialized.CacheScope);
+    }
+
+    [Fact]
+    public static void DiscoverResult_ImplementsICacheableResult()
+    {
+        // Compile-time assertion that DiscoverResult participates in the shared cacheability surface
+        // alongside the list/read result types.
+        Assert.IsAssignableFrom<ICacheableResult>(NewDiscoverResult());
+    }
+}