Created
July 1, 2019 16:02
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| describe('promiseRetry', () => { | |
| it('resolves immediately if successful', async () => { | |
| const expectedValue = 'Expected Value' | |
| const promiseFn = jest.fn().mockResolvedValue(expectedValue) | |
| const result = await promiseRetry(promiseFn) | |
| expect(promiseFn).toHaveBeenCalledTimes(1) | |
| expect(result).toBe(expectedValue) | |
| }) | |
| it('retries if unsuccessful', async () => { | |
| const expectedValue = 'Expected Value' | |
| const promiseFn = jest | |
| .fn() | |
| .mockResolvedValue(expectedValue) | |
| .mockRejectedValueOnce(new Error('Some error')) | |
| const result = await promiseRetry(promiseFn) | |
| expect(promiseFn).toHaveBeenCalledTimes(2) | |
| expect(result).toBe(expectedValue) | |
| }) | |
| it('fails if continuously unsuccessful', async () => { | |
| const expectedError = new Error('Some error') | |
| const promiseFn = jest.fn().mockRejectedValue(expectedError) | |
| expect(promiseRetry(promiseFn)).rejects.toEqual(expectedError) | |
| }) | |
| }) |
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| // Really basic, no-dependency promiseRetry implementation | |
| export const promiseRetry = ( | |
| promiseFn: () => Promise<unknown>, | |
| options: PromiseRetryOptions = {} | |
| ) => { | |
| const { retries = 5 } = options | |
| const retry = ( | |
| fn: () => Promise<unknown>, | |
| remainingAttempts: number, | |
| resolve: (value?: unknown) => void, | |
| reject: (reason?: unknown) => void | |
| ) => { | |
| fn() | |
| .then(resolve) | |
| .catch((err: Error) => { | |
| if (remainingAttempts <= 0) { | |
| return reject(err) | |
| } | |
| return retry(fn, --remainingAttempts, resolve, reject) | |
| }) | |
| } | |
| return new Promise((resolve, reject) => { | |
| retry(promiseFn, retries - 1, resolve, reject) | |
| }) | |
| } |
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