nEngine/packages/mcp/test/gateway.test.ts

import { describe, expect, it } from "vitest";
import { McpGateway, McpGatewayError } from "../src/gateway.js";
import type { McpNamespace, McpToolResult } from "../src/namespace.js";

function makeNamespace(name: string, toolNames: string[], enabled = true): McpNamespace {
  return {
    name,
    enabled,
    tools: toolNames.map((toolName) => ({
      name: toolName,
      description: `tool ${toolName}`,
      inputSchema: { type: "object", properties: {} },
      handler: (args): McpToolResult => ({
        content: [{ type: "text", text: JSON.stringify({ ns: name, tool: toolName, args }) }],
      }),
    })),
    resources: [],
    prompts: [],
  };
}

function makeResourceNamespace(): McpNamespace {
  return {
    name: "map",
    enabled: true,
    tools: [],
    resources: [
      {
        uri: "map://{mapId}",
        name: "map definition",
        read: (params) => ({ contents: [{ uri: `map://${params?.["mapId"]}`, text: `map:${params?.["mapId"]}` }] }),
      },
      {
        uri: "server://status",
        name: "server status",
        read: () => ({ contents: [{ uri: "server://status", text: "status-ok" }] }),
      },
    ],
    prompts: [
      {
        name: "orient",
        description: "onboard",
        get: () => ({ messages: [{ role: "assistant", content: { type: "text", text: "orientation" } }] }),
      },
    ],
  };
}

async function toolText(gateway: McpGateway, name: string, args: Record<string, unknown> = {}): Promise<string> {
  const result = await gateway.callTool(name, args);
  return result.content[0]?.text ?? "";
}

describe("McpGateway", () => {
  it("registers namespaces and reports status", () => {
    const gateway = new McpGateway();
    gateway.register(makeNamespace("server", ["info"]));
    gateway.register(makeNamespace("map", ["list", "get"]));
    expect(gateway.namespaces().map((ns) => ns.name)).toEqual(["server", "map"]);
    expect(gateway.status()).toEqual([
      { name: "server", enabled: true },
      { name: "map", enabled: true },
    ]);
    gateway.disable("map");
    expect(gateway.status()).toEqual([
      { name: "server", enabled: true },
      { name: "map", enabled: false },
    ]);
    gateway.enable("map");
    expect(gateway.status()[1]?.enabled).toBe(true);
  });

  it("rejects duplicate registration", () => {
    const gateway = new McpGateway();
    gateway.register(makeNamespace("server", []));
    expect(() => gateway.register(makeNamespace("server", []))).toThrow(/already registered/);
  });

  it("lists tools across namespaces with dotted names", () => {
    const gateway = new McpGateway();
    gateway.register(makeNamespace("server", ["info", "status"]));
    gateway.register(makeNamespace("map", ["list"]));
    expect(gateway.listTools().map((tool) => tool.name)).toEqual(["server.info", "server.status", "map.list"]);
    expect(gateway.listTools()[0]?.description).toBe("tool info");
  });

  it("routes callTool to the owning namespace and passes arguments", async () => {
    const gateway = new McpGateway();
    gateway.register(makeNamespace("server", ["info", "status"]));
    gateway.register(makeNamespace("map", ["list"]));
    const text = await toolText(gateway, "map.list", { extra: 1 });
    expect(JSON.parse(text)).toEqual({ ns: "map", tool: "list", args: { extra: 1 } });
  });

  it("returns an isError result for unknown tools", async () => {
    const gateway = new McpGateway();
    gateway.register(makeNamespace("server", ["info"]));
    const result = await gateway.callTool("map.list", {});
    expect(result.isError).toBe(true);
    expect(result.content[0]?.text).toMatch(/tool not found: map\.list/);
  });

  it("validates required inputSchema arguments", async () => {
    const gateway = new McpGateway();
    gateway.register({
      name: "time",
      enabled: true,
      tools: [
        {
          name: "advance",
          description: "advance",
          inputSchema: {
            type: "object",
            properties: { ticks: { type: "number" } },
            required: ["ticks"],
          },
          handler: (args) => ({ content: [{ type: "text", text: `advanced ${String(args["ticks"])}` }] }),
        },
      ],
      resources: [],
      prompts: [],
    });
    const ok = await gateway.callTool("time.advance", { ticks: 3 });
    expect(ok.isError).toBeUndefined();
    expect(ok.content[0]?.text).toBe("advanced 3");
    const missing = await gateway.callTool("time.advance", {});
    expect(missing.isError).toBe(true);
    expect(missing.content[0]?.text).toMatch(/missing required arguments: ticks/);
  });

  it("excludes disabled namespaces from listings", () => {
    const gateway = new McpGateway();
    gateway.register(makeNamespace("server", ["info"]));
    gateway.register(makeNamespace("map", ["list", "get"]));
    gateway.disable("map");
    expect(gateway.listTools().map((tool) => tool.name)).toEqual(["server.info"]);
  });

  it("rejects tool calls on a disabled namespace with a clear error", async () => {
    const gateway = new McpGateway();
    gateway.register(makeNamespace("server", ["info"]));
    gateway.register(makeNamespace("map", ["list"]));
    gateway.disable("map");
    const result = await gateway.callTool("map.list", {});
    expect(result.isError).toBe(true);
    expect(result.content[0]?.text).toMatch(/namespace "map" is disabled/);
  });

  it("lists resources and routes concrete and template URIs", async () => {
    const gateway = new McpGateway();
    gateway.register(makeResourceNamespace());
    expect(gateway.listResources().map((resource) => resource.uri)).toEqual(["map://{mapId}", "server://status"]);
    const concrete = await gateway.readResource("server://status");
    expect(concrete.contents[0]?.text).toBe("status-ok");
    const templated = await gateway.readResource("map://farm");
    expect(templated.contents[0]).toEqual({ uri: "map://farm", text: "map:farm" });
  });

  it("throws for unknown resources", async () => {
    const gateway = new McpGateway();
    gateway.register(makeResourceNamespace());
    await expect(gateway.readResource("item://nope")).rejects.toThrow(McpGatewayError);
    await expect(gateway.readResource("item://nope")).rejects.toThrow(/resource not found/);
  });

  it("lists and gets prompts", async () => {
    const gateway = new McpGateway();
    gateway.register(makeResourceNamespace());
    expect(gateway.listPrompts().map((prompt) => prompt.name)).toEqual(["map.orient"]);
    const prompt = await gateway.getPrompt("map.orient", {});
    expect(prompt.messages[0]?.content.text).toBe("orientation");
  });

  it("throws for unknown prompts", async () => {
    const gateway = new McpGateway();
    gateway.register(makeResourceNamespace());
    await expect(gateway.getPrompt("server.nope", {})).rejects.toThrow(/prompt not found/);
  });

  it("blocks disabled namespaces across resources and prompts", async () => {
    const gateway = new McpGateway();
    gateway.register(makeResourceNamespace());
    gateway.disable("map");
    await expect(gateway.readResource("map://farm")).rejects.toThrow(/disabled/);
    await expect(gateway.getPrompt("map.orient", {})).rejects.toThrow(/disabled/);
  });
});