feat: Added retry utility functions

package/commonUtil/index.ts

@@ -6,4 +6,5 @@ export { default as encodeBase64 } from "./encodeBase64";
 export { default as decodeBase64 } from "./decodeBase64";
 export { default as debounce } from "./debounce";
 export { default as throttle } from "./throttle";
-export { default as storage } from "./storage";
+export { default as retry } from "./retry";
+export { default as storage } from "./storage";

package/commonUtil/retry/index.test.ts

@@ -0,0 +1,66 @@
+import { describe, expect, test, vi } from "vitest";
+import retry from ".";
+
+describe("retry 유틸 함수 테스트", () => {
+  test("정상적으로 실행되는 함수는 한번만 실행한다.", async () => {
+    const fn = vi.fn().mockResolvedValue("success!");
+
+    const result = await retry(fn, 3);
+
+    expect(result).toBe("success!");
+    expect(fn).toHaveBeenCalledTimes(1);
+  });
+
+  test("함수를 실행하며 오류가 발생하면 재시도한다.", async () => {
+    const fn = vi
+      .fn()
+      .mockRejectedValueOnce(new Error("fail 1"))
+      .mockRejectedValueOnce(new Error("fail 2"))
+      .mockResolvedValue("success!");
+
+    const result = await retry(fn, 3);
+
+    expect(result).toBe("success!");
+    expect(fn).toHaveBeenCalledTimes(3);
+  });
+
+  test("재시도 한도를 초과하면 마지막 에러를 던진다.", async () => {
+    const error = new Error("always fail");
+    const fn = vi.fn().mockRejectedValue(error);
+
+    await expect(retry(fn, 2)).rejects.toThrow("always fail");
+    expect(fn).toHaveBeenCalledTimes(3);
+  });
+
+  test("기본 재시도 횟수는 3번이다.", async () => {
+    const fn = vi.fn().mockRejectedValue(new Error("fail"));
+
+    await expect(retry(fn)).rejects.toThrow("fail");
+    expect(fn).toHaveBeenCalledTimes(4);
+  });
+
+  test("타입 안전성: 반환 타입이 올바르게 추론된다.", async () => {
+    const stringFn = vi.fn().mockResolvedValue("hello");
+    const numberFn = vi.fn().mockResolvedValue(42);
+    const objectFn = vi.fn().mockResolvedValue({ id: 1 });
+
+    const stringResult = await retry(stringFn);
+    const numberResult = await retry(numberFn);
+    const objectResult = await retry(objectFn);
+
+    expect(typeof stringResult).toBe("string");
+    expect(typeof numberResult).toBe("number");
+    expect(typeof objectResult).toBe("object");
+
+    expect(stringResult).toBe("hello");
+    expect(numberResult).toBe(42);
+    expect(objectResult).toEqual({ id: 1 });
+  });
+
+  test("0번 재시도 시 한 번만 실행한다.", async () => {
+    const fn = vi.fn().mockRejectedValue(new Error("fail"));
+
+    await expect(retry(fn, 0)).rejects.toThrow("fail");
+    expect(fn).toHaveBeenCalledTimes(1);
+  });
+});

package/commonUtil/retry/index.ts

@@ -0,0 +1,21 @@
+export default async function retry<T>(
+  fn: () => Promise<T>,
+  loop: number = 3
+): Promise<T> {
+  let count = 0;
+
+  const attempt = async (): Promise<T> => {
+    try {
+      return await fn();
+    } catch (e) {
+      count++;
+      if (count > loop) {
+        throw e;
+      }
+      console.error(`Retry attempt ${count} / ${loop} failed:`, e);
+      return attempt();
+    }
+  };
+
+  return attempt();
+}