alepha/src/mcp/__tests__/$resource.spec.ts

Easy-to-use modern TypeScript framework for building many kind of applications.

import { Alepha } from "alepha";
import { describe, expect, test } from "vitest";
import {
  $resource,
  AlephaMcp,
  type McpContext,
  McpServerProvider,
} from "../index.ts";

// ---------------------------------------------------------------------------------------------------------------------

describe("$resource primitive", () => {
  test("should register resource with McpServerProvider", async () => {
    const alepha = Alepha.create();

    class Resources {
      readme = $resource({
        uri: "file:///readme",
        description: "Project README",
        handler: async () => ({ text: "# README" }),
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("file:///readme");

    expect(resource).toBeDefined();
    expect(resource?.uri).toBe("file:///readme");
    expect(resource?.description).toBe("Project README");
  });

  test("should use property key as name when not provided", async () => {
    const alepha = Alepha.create();

    class Resources {
      myResource = $resource({
        uri: "test://resource",
        handler: async () => ({ text: "content" }),
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("test://resource");

    expect(resource?.name).toBe("myResource");
  });

  test("should use custom name when provided", async () => {
    const alepha = Alepha.create();

    class Resources {
      myResource = $resource({
        uri: "test://resource",
        name: "Custom Resource Name",
        handler: async () => ({ text: "content" }),
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("test://resource");

    expect(resource?.name).toBe("Custom Resource Name");
  });

  test("should return text content", async () => {
    const alepha = Alepha.create();

    class Resources {
      text = $resource({
        uri: "text://content",
        handler: async () => ({ text: "Hello, World!" }),
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("text://content");

    const content = await resource?.read();
    expect(content?.text).toBe("Hello, World!");
  });

  test("should return binary content", async () => {
    const alepha = Alepha.create();

    const binaryData = new Uint8Array([1, 2, 3, 4, 5]);

    class Resources {
      binary = $resource({
        uri: "binary://data",
        mimeType: "application/octet-stream",
        handler: async () => ({ blob: binaryData }),
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("binary://data");

    const content = await resource?.read();
    expect(content?.blob).toEqual(binaryData);
  });

  test("should use default mimeType when not provided", async () => {
    const alepha = Alepha.create();

    class Resources {
      plain = $resource({
        uri: "plain://text",
        handler: async () => ({ text: "plain text" }),
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("plain://text");

    expect(resource?.mimeType).toBe("text/plain");
  });

  test("should use custom mimeType", async () => {
    const alepha = Alepha.create();

    class Resources {
      json = $resource({
        uri: "json://data",
        mimeType: "application/json",
        handler: async () => ({ text: '{"key": "value"}' }),
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("json://data");

    expect(resource?.mimeType).toBe("application/json");
  });

  test("should generate correct descriptor", async () => {
    const alepha = Alepha.create();

    class Resources {
      config = $resource({
        uri: "config://app",
        name: "Application Config",
        description: "Application configuration file",
        mimeType: "application/json",
        handler: async () => ({ text: "{}" }),
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("config://app");
    const descriptor = resource?.toDescriptor();

    expect(descriptor).toEqual({
      uri: "config://app",
      name: "Application Config",
      description: "Application configuration file",
      mimeType: "application/json",
    });
  });

  test("should handle async handlers", async () => {
    const alepha = Alepha.create();

    class Resources {
      async = $resource({
        uri: "async://resource",
        handler: async () => {
          await new Promise((resolve) => setTimeout(resolve, 10));
          return { text: "async content" };
        },
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("async://resource");

    const content = await resource?.read();
    expect(content?.text).toBe("async content");
  });

  test("should propagate handler errors", async () => {
    const alepha = Alepha.create();

    class Resources {
      failing = $resource({
        uri: "failing://resource",
        handler: async () => {
          throw new Error("Resource read failed");
        },
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("failing://resource");

    await expect(resource?.read()).rejects.toThrow("Resource read failed");
  });

  test("should handle dynamic content", async () => {
    const alepha = Alepha.create();

    let counter = 0;

    class Resources {
      dynamic = $resource({
        uri: "dynamic://counter",
        handler: async () => {
          counter++;
          return { text: `Count: ${counter}` };
        },
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("dynamic://counter");

    const content1 = await resource?.read();
    expect(content1?.text).toBe("Count: 1");

    const content2 = await resource?.read();
    expect(content2?.text).toBe("Count: 2");
  });

  // -----------------------------------------------------------------------------------------------------------------
  // Context tests
  // -----------------------------------------------------------------------------------------------------------------

  test("should receive context in handler", async () => {
    const alepha = Alepha.create();

    let receivedContext: McpContext | undefined;

    class Resources {
      contextResource = $resource({
        uri: "context://resource",
        handler: async ({ context }) => {
          receivedContext = context;
          return { text: "content" };
        },
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("context://resource");

    const testContext: McpContext = {
      headers: { authorization: "Bearer test-token" },
    };

    await resource?.read(testContext);

    expect(receivedContext).toBeDefined();
    expect(receivedContext?.headers?.authorization).toBe("Bearer test-token");
  });

  test("should receive context with custom data", async () => {
    const alepha = Alepha.create();

    interface UserContext {
      userId: string;
      projectId: number;
    }

    let receivedData: UserContext | undefined;

    class Resources {
      userResource = $resource({
        uri: "user://data",
        handler: async ({ context }) => {
          receivedData = context?.data as UserContext;
          return {
            text: JSON.stringify({
              userId: receivedData?.userId,
              projectId: receivedData?.projectId,
            }),
          };
        },
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("user://data");

    const testContext: McpContext<UserContext> = {
      headers: {},
      data: { userId: "user-456", projectId: 123 },
    };

    const content = await resource?.read(testContext);

    expect(content?.text).toBe('{"userId":"user-456","projectId":123}');
    expect(receivedData).toEqual({ userId: "user-456", projectId: 123 });
  });

  test("should work without context", async () => {
    const alepha = Alepha.create();

    let contextWasUndefined = false;

    class Resources {
      noContext = $resource({
        uri: "no://context",
        handler: async ({ context }) => {
          contextWasUndefined = context === undefined;
          return { text: "done" };
        },
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("no://context");

    await resource?.read();

    expect(contextWasUndefined).toBe(true);
  });

  test("should use context for access control", async () => {
    const alepha = Alepha.create();

    class Resources {
      protected = $resource({
        uri: "protected://resource",
        handler: async ({ context }) => {
          const authHeader = context?.headers?.authorization;
          if (!authHeader?.toString().startsWith("Bearer ")) {
            throw new Error("Unauthorized");
          }
          return { text: "Secret content" };
        },
      });
    }

    alepha.with(AlephaMcp).with(Resources);
    await alepha.start();

    const provider = alepha.inject(McpServerProvider);
    const resource = provider.getResource("protected://resource");

    // Without auth - should fail
    await expect(resource?.read()).rejects.toThrow("Unauthorized");

    // With auth - should succeed
    const content = await resource?.read({
      headers: { authorization: "Bearer valid-token" },
    });
    expect(content?.text).toBe("Secret content");
  });
});