Add tests for API endpoints, liked store, listen tracker and paged list

web-player/src/lib/state/liked.test.ts

@@ -0,0 +1,80 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import type { LikedTrack, Track } from '$lib/types';
+
+function track(id: string): Track {
+	return {
+		id,
+		title: id,
+		artist: 'Artist',
+		duration: 100,
+		explicit: false,
+		listensCount: 0
+	} as unknown as Track;
+}
+
+function likedTrack(id: string): LikedTrack {
+	return { ...track(id), likedAt: 1 } as LikedTrack;
+}
+
+async function freshStore() {
+	vi.resetModules();
+	return (await import('./liked.svelte')).liked;
+}
+
+afterEach(() => {
+	vi.unstubAllGlobals();
+});
+
+describe('liked store', () => {
+	it('hydrates only once', async () => {
+		const liked = await freshStore();
+		liked.hydrate([likedTrack('a')]);
+		liked.hydrate([likedTrack('b')]);
+		expect(liked.isLiked('a')).toBe(true);
+		expect(liked.isLiked('b')).toBe(false);
+		expect(liked.count).toBe(1);
+	});
+
+	it('likes and unlikes a track', async () => {
+		vi.stubGlobal('fetch', vi.fn().mockResolvedValue({ ok: true }));
+		const liked = await freshStore();
+		await liked.toggle(track('a'));
+		expect(liked.isLiked('a')).toBe(true);
+		await liked.toggle(track('a'));
+		expect(liked.isLiked('a')).toBe(false);
+		expect(fetch).toHaveBeenCalledTimes(2);
+	});
+
+	it('reverts a failed like', async () => {
+		vi.stubGlobal('fetch', vi.fn().mockResolvedValue({ ok: false }));
+		const liked = await freshStore();
+		await liked.toggle(track('a'));
+		expect(liked.isLiked('a')).toBe(false);
+	});
+
+	it('reverts a failed unlike', async () => {
+		const liked = await freshStore();
+		liked.hydrate([likedTrack('a')]);
+		vi.stubGlobal('fetch', vi.fn().mockRejectedValue(new Error('offline')));
+		await liked.toggle(track('a'));
+		expect(liked.isLiked('a')).toBe(true);
+	});
+
+	it('keeps changes made to other tracks while a request fails', async () => {
+		const liked = await freshStore();
+		let rejectFirst: (reason: Error) => void = () => {};
+		const fetchMock = vi
+			.fn()
+			.mockImplementationOnce(() => new Promise((_, reject) => (rejectFirst = reject)))
+			.mockResolvedValueOnce({ ok: true });
+		vi.stubGlobal('fetch', fetchMock);
+
+		const first = liked.toggle(track('a'));
+		await liked.toggle(track('b'));
+		rejectFirst(new Error('offline'));
+		await first;
+
+		expect(liked.isLiked('a')).toBe(false);
+		expect(liked.isLiked('b')).toBe(true);
+	});
+});