t-youtube-transcript-fetcher/dist/src/__tests__/transcript.test.js

An enhanced TypeScript library for fetching YouTube transcripts with proxy support (based on youtube-transcript)

import { jest } from '@jest/globals';
import { TranscriptError, RateLimitError, VideoUnavailableError, TranscriptDisabledError, LanguageNotFoundError } from '../errors.js';
// Set up mocks before importing modules that use them
const mockFetch = jest.fn();
jest.unstable_mockModule('node-fetch', () => ({
    default: mockFetch
}));
// Import after setting up mocks
const { YoutubeTranscript } = await import('../transcript.js');
describe('YoutubeTranscript', () => {
    beforeEach(() => {
        jest.clearAllMocks();
    });
    describe('retrieveVideoId', () => {
        const testCases = [
            {
                name: 'direct video ID',
                input: 'dQw4w9WgXcQ',
                expected: 'dQw4w9WgXcQ'
            },
            {
                name: 'youtube.com/watch URL',
                input: 'https://www.youtube.com/watch?v=dQw4w9WgXcQ',
                expected: 'dQw4w9WgXcQ'
            },
            {
                name: 'youtu.be short URL',
                input: 'https://youtu.be/dQw4w9WgXcQ',
                expected: 'dQw4w9WgXcQ'
            },
            {
                name: 'youtube.com/embed URL',
                input: 'https://www.youtube.com/embed/dQw4w9WgXcQ',
                expected: 'dQw4w9WgXcQ'
            }
        ];
        testCases.forEach(({ name, input, expected }) => {
            it(`should extract video ID from ${name}`, async () => {
                mockFetch.mockImplementationOnce(() => Promise.resolve({
                    text: () => Promise.resolve('Mock response'),
                    ok: true
                }));
                await expect(YoutubeTranscript.fetchTranscript(input)).rejects.toThrow();
                expect(mockFetch).toHaveBeenCalledWith(expect.stringContaining(expected), expect.any(Object));
            });
        });
        it('should throw error for invalid video ID format', async () => {
            await expect(YoutubeTranscript.fetchTranscript('invalid-id'))
                .rejects
                .toThrow(TranscriptError);
        });
    });
    describe('fetchTranscript', () => {
        const validVideoId = 'dQw4w9WgXcQ';
        const mockCaptionsData = {
            playerCaptionsTracklistRenderer: {
                captionTracks: [
                    {
                        baseUrl: 'https://youtube.com/api/timedtext',
                        languageCode: 'en'
                    }
                ]
            }
        };
        const mockTranscriptXml = `
      <transcript>
        <text start="0" dur="2.5">First caption</text>
        <text start="2.5" dur="3.0">Second caption</text>
      </transcript>
    `;
        it('should fetch and parse transcript successfully', async () => {
            // Mock the video page response
            mockFetch
                .mockImplementationOnce(() => Promise.resolve({
                text: () => Promise.resolve(`"captions":${JSON.stringify(mockCaptionsData)},"videoDetails"`)
            }))
                // Mock the transcript XML response
                .mockImplementationOnce(() => Promise.resolve({
                text: () => Promise.resolve(mockTranscriptXml),
                ok: true
            }));
            const transcript = await YoutubeTranscript.fetchTranscript(validVideoId);
            expect(transcript).toHaveLength(2);
            expect(transcript[0]).toEqual({
                text: 'First caption',
                duration: 2.5,
                offset: 0,
                lang: 'en'
            });
        });
        it('should handle rate limit error', async () => {
            mockFetch.mockImplementationOnce(() => Promise.resolve({
                text: () => Promise.resolve('<div class="g-recaptcha"></div>')
            }));
            await expect(YoutubeTranscript.fetchTranscript(validVideoId))
                .rejects
                .toThrow(RateLimitError);
        });
        it('should handle video unavailable error', async () => {
            mockFetch.mockImplementationOnce(() => Promise.resolve({
                text: () => Promise.resolve('Video unavailable')
            }));
            await expect(YoutubeTranscript.fetchTranscript(validVideoId))
                .rejects
                .toThrow(VideoUnavailableError);
        });
        it('should handle transcript disabled error', async () => {
            mockFetch.mockImplementationOnce(() => Promise.resolve({
                text: () => Promise.resolve('"playabilityStatus":{"status":"OK"}')
            }));
            await expect(YoutubeTranscript.fetchTranscript(validVideoId))
                .rejects
                .toThrow(TranscriptDisabledError);
        });
        it('should handle language not found error', async () => {
            mockFetch.mockImplementationOnce(() => Promise.resolve({
                text: () => Promise.resolve(`"captions":${JSON.stringify(mockCaptionsData)},"videoDetails"`)
            }));
            await expect(YoutubeTranscript.fetchTranscript(validVideoId, { lang: 'fr' }))
                .rejects
                .toThrow(LanguageNotFoundError);
        });
    });
});