ts-mcp-template/tests/capability-contracts.test.ts

import { describe, expect, it } from "vitest";
import { AppError } from "../src/lib/errors.js";
import {
  parseExampleEchoToolInput,
  parseExampleSummaryPromptInput,
  renderExampleSummaryPrompt,
  runExampleEchoTool,
} from "../src/capabilities/index.js";

describe("example capability contracts", () => {
  it("accepts valid tool input and applies uppercase transform", () => {
    expect(
      parseExampleEchoToolInput({ message: "  hello team  ", uppercase: true }),
    ).toEqual({
      message: "hello team",
      uppercase: true,
    });

    expect(runExampleEchoTool({ message: "hello", uppercase: true })).toEqual({
      output: "HELLO",
    });
  });

  it("rejects invalid tool input shapes", () => {
    expect(() => parseExampleEchoToolInput("bad-input")).toThrow(AppError);
    expect(() => parseExampleEchoToolInput({ message: "" })).toThrow(
      "message must not be empty",
    );
    expect(() =>
      parseExampleEchoToolInput({ message: "valid", uppercase: "yes" }),
    ).toThrow("uppercase must be a boolean when provided");
  });

  it("accepts valid prompt input and renders generic prompt text", () => {
    expect(
      parseExampleSummaryPromptInput({
        topic: "event-driven systems",
        audience: "new contributors",
      }),
    ).toEqual({
      topic: "event-driven systems",
      audience: "new contributors",
    });

    expect(
      renderExampleSummaryPrompt({
        topic: "API design",
      }),
    ).toBe("Write a concise summary about API design.");
  });

  it("rejects invalid prompt input shapes", () => {
    expect(() => parseExampleSummaryPromptInput(null)).toThrow(AppError);
    expect(() => parseExampleSummaryPromptInput({ topic: 42 })).toThrow(
      "topic must be a string",
    );
    expect(() =>
      parseExampleSummaryPromptInput({
        topic: "valid topic",
        audience: "   ",
      }),
    ).toThrow("audience must not be empty");
  });
});