retryAsync - retry an async function a set amount of times

retryAsync.spec.ts

import retryAsync from '~utils/retryAsync';

describe('retryAsync', () => {
  describe('with retry attempts left', () => {
    describe('if the async function promise rejects', () => {
      it('retries the given async function 3 times before eventually throwing', async () => {
        const mockAsyncFn = jest.fn().mockRejectedValue('failed');

        await expect(retryAsync(3, () => mockAsyncFn())).rejects.toThrow();
        expect(mockAsyncFn).toHaveBeenCalledTimes(3);
      });
    });

    describe('if the async function promise resolves', () => {
      it("returns the async function's payload", async () => {
        const mockAsyncFn = jest.fn().mockResolvedValue('success');

        await expect(retryAsync(3, () => mockAsyncFn())).resolves.toEqual('success');
        expect(mockAsyncFn).toHaveBeenCalledTimes(1);
      });
    });

    describe('if the async function fails a couple of times before eventually resolving', () => {
      it("returns the async function's payload", async () => {
        const mockAsyncFn = jest.fn();
        mockAsyncFn.mockRejectedValueOnce('failed1').mockRejectedValueOnce('failed2').mockResolvedValueOnce('success');

        await expect(retryAsync(3, () => mockAsyncFn())).resolves.toEqual('success');
        expect(mockAsyncFn).toHaveBeenCalledTimes(3);
      });
    });
  });

  describe('without retry attempts left', () => {
    describe('if the async function rejects', () => {
      it('throws', async () => {
        const mockAsyncFn = jest.fn().mockRejectedValue('failed');

        await expect(retryAsync(3, () => mockAsyncFn())).rejects.toThrow();
        expect(mockAsyncFn).toHaveBeenCalledTimes(3);
      });
    });
  });
});

retryAsync.ts

export default async function retryAsync<AsyncFn>(retries: number, asyncFn: () => Promise<AsyncFn>): Promise<AsyncFn> {
  try {
    retries--;
    return await asyncFn();
  } catch (err: any) {
    if (retries === 0) {
      throw new Error(err);
    }
    return retryAsync(retries, asyncFn);
  }
}