feat: 기능 추가 과정중

tests/unit/system-clock.test.ts

@@ -0,0 +1,18 @@
+import { describe, expect, it, vi } from "vitest";
+
+import { systemClock } from "../../src/adapters/platform/system-clock.ts";
+
+describe("systemClock", () => {
+  it("resolves after the requested duration", async () => {
+    vi.useFakeTimers();
+    const caller = new AbortController();
+    const add = vi.spyOn(caller.signal, "addEventListener");
+    const remove = vi.spyOn(caller.signal, "removeEventListener");
+    const sleeper = systemClock.sleep(250, caller.signal);
+    await vi.advanceTimersByTimeAsync(250);
+    await expect(sleeper).resolves.toBeUndefined();
+    expect(add).toHaveBeenCalledOnce();
+    expect(remove).toHaveBeenCalledOnce();
+    vi.useRealTimers();
+  });
+});