Merge pull request #66 from team-layer/feature/65

feat: Added retry utility functions

Author: klmhyeonwoo

README.md

@@ -82,6 +82,22 @@ commonUtil.storage.set("user", { id: 1, name: "John" }); // Stores object in loc
 const user = commonUtil.storage.get<{ id: number; name: string }>("user"); // Retrieves typed object
 commonUtil.storage.remove("user"); // Removes item from localStorage
 
+// Retry utilities
+const result = await commonUtil.retry(async () => {
+  const response = await fetch("/api/data");
+  if (!response.ok) throw new Error("API failed");
+  return response.json();
+}, 3); // Retry up to 3 times
+
+// More retry examples
+const userData = await commonUtil.retry(async () => {
+  return await fetchUserData();
+}); // Uses default 3 retries
+
+const fileUpload = await commonUtil.retry(async () => {
+  return await uploadFile(file);
+}, 5); // Custom retry count
+
 // Search Query utilities
 const queryParams = searchQueryUtil.getAllQuery(); // { key: ["value1", "value2"], id: "123" }
 
@@ -193,6 +209,9 @@ storage.set("data", { key: "value" });
 - 🛡️ **Error Handling**: Comprehensive error handling with automatic cleanup of corrupted data
 - 🔄 **Auto Serialization**: Automatic JSON serialization/deserialization for complex data types
 
+### Retry
+
+- `retry<T>(fn: () => Promise<T>, loop?: number): Promise<T>` - Retries an asynchronous function up to the specified number of times (default 3) if it fails. Automatically re-attempts on error and returns the result of the first successful execution, or throws the last error if all retries fail.
 ### SearchQueryUtil
 
 - `getAllQuery(): Record<string, string | string[]>` - Parses the current URL's query string and returns an object with key-value pairs. Values appear as arrays when the same key is used multiple times.

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(2);
+  });
+
+  test("기본 재시도 횟수는 3번이다.", async () => {
+    const fn = vi.fn().mockRejectedValue(new Error("fail"));
+
+    await expect(retry(fn)).rejects.toThrow("fail");
+    expect(fn).toHaveBeenCalledTimes(3);
+  });
+
+  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 +1,20 @@
+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;
+      }
+      return attempt();
+    }
+  };
+
+  return attempt();
+}