@arturwojnar/hermes-postgresql/lib/outbox/publishingQueue.test.js

Production-Ready TypeScript Outbox Pattern for PostgreSQL

import { Duration } from '@arturwojnar/hermes';
import { describe, expect, it, jest } from '@jest/globals';
import { setTimeout as setTimeoutCallback } from 'timers';
import { setTimeout } from 'timers/promises';
import { createPublishingQueue } from './publishingQueue.js';
describe('publishingQueue', () => {
    const createMockTransaction = (lsn) => ({
        transactionId: 1,
        lsn,
        timestamp: new Date(),
        results: [],
    });
    const createMockMessage = (lsn) => ({
        transaction: createMockTransaction(lsn),
        acknowledge: jest.fn(),
    });
    const createMockPublish = () => jest.fn().mockImplementation(async () => { });
    it('should queue unique messages', () => {
        const mockPublish = createMockPublish();
        const queue = createPublishingQueue(mockPublish);
        const message1 = createMockMessage('0/1');
        const message2 = createMockMessage('0/2');
        queue.queue(message1);
        queue.queue(message2);
        expect(queue.size()).toBe(2);
        expect(mockPublish).not.toHaveBeenCalled();
    });
    it('should ignore duplicate messages based on LSN', () => {
        const mockPublish = createMockPublish();
        const queue = createPublishingQueue(mockPublish);
        const message1 = createMockMessage('0/1');
        const message2 = createMockMessage('0/1');
        queue.queue(message1);
        queue.queue(message2);
        expect(queue.size()).toBe(1);
        expect(mockPublish).not.toHaveBeenCalled();
    });
    it('should publish messages in FIFO order', async () => {
        const publishedMessages = [];
        const mockPublish = jest
            .fn()
            .mockImplementation(async (message) => {
            publishedMessages.push(message.transaction.lsn);
        });
        const { queue, publishMessages, size } = createPublishingQueue(mockPublish);
        const message1 = createMockMessage('0/1');
        const message2 = createMockMessage('0/2');
        const message3 = createMockMessage('0/3');
        queue(message1);
        queue(message2);
        queue(message3);
        await publishMessages();
        expect(publishedMessages).toEqual(['0/1', '0/2', '0/3']);
        expect(size()).toBe(0);
    });
    it('should continue publishing after failed messages', async () => {
        const mockError = new Error('Publish failed');
        const publishedMessages = [];
        const mockPublish = jest
            .fn()
            .mockImplementationOnce(async () => {
            throw mockError;
        })
            .mockImplementation(async (message) => {
            publishedMessages.push(message.transaction.lsn);
        });
        const mockFailedPublishCallback = jest
            .fn(async (tx) => { })
            .mockImplementation(async (tx) => {
            return Promise.resolve();
        });
        const { queue, publishMessages } = createPublishingQueue(mockPublish, {
            waitAfterFailedPublish: Duration.ofMiliseconds(1),
            onFailedPublish: mockFailedPublishCallback,
        });
        const message1 = createMockMessage('0/1');
        const message2 = createMockMessage('0/2');
        const message3 = createMockMessage('0/3');
        queue(message1);
        queue(message2);
        queue(message3);
        await publishMessages();
        expect(mockFailedPublishCallback).toHaveBeenCalledWith(message1.transaction);
        expect(mockFailedPublishCallback).toHaveBeenCalledTimes(1);
        expect(publishedMessages).toEqual(['0/1', '0/2', '0/3']);
    });
    it('should keep retrying failed message until success', async () => {
        const mockError = new Error('Publish failed');
        const publishedMessages = [];
        const mockPublish = jest
            .fn()
            .mockRejectedValueOnce(mockError)
            .mockRejectedValueOnce(mockError)
            .mockImplementation(async (message) => {
            publishedMessages.push(message.transaction.lsn);
        });
        const mockFailedPublishCallback = jest
            .fn(async (tx) => { })
            .mockImplementation(async (tx) => {
            return Promise.resolve();
        });
        const { queue, publishMessages } = createPublishingQueue(mockPublish, {
            waitAfterFailedPublish: Duration.ofMiliseconds(10),
            onFailedPublish: mockFailedPublishCallback,
        });
        const message = createMockMessage('0/1');
        queue(message);
        await publishMessages();
        expect(mockPublish).toHaveBeenCalledTimes(3);
        expect(mockFailedPublishCallback).toHaveBeenCalledTimes(2);
        expect(publishedMessages).toEqual(['0/1']);
    });
    it('should publish all queued messages until queue is empty', async () => {
        const publishedMessages = [];
        const mockPublish = jest
            .fn()
            .mockImplementation(async (message) => {
            await setTimeout(100);
            publishedMessages.push(message.transaction.lsn);
        });
        const { queue, publishMessages } = createPublishingQueue(mockPublish);
        const messages = [
            createMockMessage('0/1'),
            createMockMessage('0/2'),
            createMockMessage('0/3'),
            createMockMessage('0/4'),
            createMockMessage('0/5'),
        ];
        const laterMessage = createMockMessage('0/100');
        messages.forEach((msg) => queue(msg));
        setTimeoutCallback(() => {
            queue(laterMessage);
        }, 330);
        await publishMessages();
        expect(mockPublish).toHaveBeenCalledTimes(6);
        expect(publishedMessages).toEqual(['0/1', '0/2', '0/3', '0/4', '0/5', '0/100']);
    });
    it('should prevent concurrent publishing', async () => {
        const mockPublish = jest
            .fn()
            .mockImplementation(async () => await setTimeout(100));
        const { queue, publishMessages } = createPublishingQueue(mockPublish);
        queue(createMockMessage('0/1'));
        queue(createMockMessage('0/2'));
        const publish1 = publishMessages();
        const publish2 = publishMessages();
        await Promise.all([publish1, publish2]);
        expect(mockPublish).toHaveBeenCalledTimes(2);
    });
});
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