agentic-dev/packages/core-analytics/src/with-analytics.test.ts

import { describe, it, expect, expectTypeOf } from "vitest";
import { withAnalytics, type Analyzed } from "@/with-analytics";
import type { IAnalytics } from "@/analytics.interface";
import { isAnalyzed } from "@repo/core-shared/conformance";

function makeAnalytics(): IAnalytics {
  return {
    track: () => undefined,
    identify: () => undefined,
    pageView: () => undefined,
    flush: () => Promise.resolve(),
  };
}

describe("withAnalytics", () => {
  it("returns an Analyzed<F>", () => {
    const analytics = makeAnalytics();
    const fn = async (_input: { id: string }) => ({ ok: true });
    const wrapped = withAnalytics(analytics, fn);
    expectTypeOf(wrapped).toMatchTypeOf<Analyzed<typeof fn>>();
  });

  it("attaches __analyzed as a non-enumerable property on the wrapped function", () => {
    const analytics = makeAnalytics();
    const fn = async () => ({ ok: true });
    const wrapped = withAnalytics(analytics, fn);
    expect(isAnalyzed(wrapped)).toBe(true);
    expect(Object.keys(wrapped)).not.toContain("__analyzed");
  });

  it("does NOT pollute the original input function with the brand", () => {
    const analytics = makeAnalytics();
    const fn = async () => ({ ok: true });
    const wrapped = withAnalytics(analytics, fn);
    expect(isAnalyzed(fn)).toBe(false);
    expect(wrapped).not.toBe(fn);
  });

  it("passes input and output through unchanged", async () => {
    const analytics = makeAnalytics();
    const fn = async (input: { id: string }) => ({ ok: true, id: input.id });
    const wrapped = withAnalytics(analytics, fn);
    const result = await wrapped({ id: "abc" });
    expect(result).toEqual({ ok: true, id: "abc" });
  });

  it("propagates errors", async () => {
    const analytics = makeAnalytics();
    const err = new Error("boom");
    const wrapped = withAnalytics(analytics, async () => {
      throw err;
    });
    await expect(wrapped()).rejects.toBe(err);
  });
});