subscription-registry.test.ts64 lines · main

1	import { describe, expect, it } from 'bun:test';
2
3	import { SubscriptionRegistry } from './subscription-registry.js';
4
5	describe('SubscriptionRegistry — Phase 1 §1.1 ref-counting invariants', () => {
6	it('add → add same → remove → remove same → empty', () => {
7	const r = new SubscriptionRegistry();
8
9	// First attach to an empty channel returns true so the caller knows
10	// to issue LISTEN exactly once per channel.
11	expect(r.attach('s1', 'c1')).toBe(true);
12	expect(r.hasChannel('c1')).toBe(true);
13	expect(r.channelCount).toBe(1);
14
15	// Idempotent attach — same sub, same channel — returns false because
16	// the channel is no longer empty. Set semantics mean no duplicate entry.
17	expect(r.attach('s1', 'c1')).toBe(false);
18	expect(r.subsForChannel('c1')).toEqual(['s1']);
19	expect(r.channelCount).toBe(1);
20
21	// Last detach drains the set → returns true → caller issues UNLISTEN.
22	expect(r.detach('s1', 'c1')).toBe(true);
23	expect(r.hasChannel('c1')).toBe(false);
24	expect(r.channelCount).toBe(0);
25
26	// Detach the same sub again from the same (now-gone) channel: no-op,
27	// returns false. Caller must not double-UNLISTEN.
28	expect(r.detach('s1', 'c1')).toBe(false);
29	expect(r.channelCount).toBe(0);
30	expect(r.subsForChannel('c1')).toEqual([]);
31	});
32
33	it('multiple subs on a channel: only first attach and last detach return true', () => {
34	const r = new SubscriptionRegistry();
35
36	expect(r.attach('s1', 'c1')).toBe(true); // first → LISTEN
37	expect(r.attach('s2', 'c1')).toBe(false); // ref + 1
38	expect(r.attach('s3', 'c1')).toBe(false); // ref + 1
39
40	expect(r.subsForChannel('c1').slice().sort()).toEqual(['s1', 's2', 's3']);
41
42	expect(r.detach('s2', 'c1')).toBe(false); // ref - 1, still has subs
43	expect(r.detach('s1', 'c1')).toBe(false); // ref - 1, still has subs
44	expect(r.detach('s3', 'c1')).toBe(true); // last → UNLISTEN
45	expect(r.hasChannel('c1')).toBe(false);
46	});
47
48	it('detach of unknown sub is a no-op false', () => {
49	const r = new SubscriptionRegistry();
50	r.attach('s1', 'c1');
51	expect(r.detach('s-bogus', 'c1')).toBe(false);
52	expect(r.subsForChannel('c1')).toEqual(['s1']);
53	});
54
55	it('subsForChannel returns a snapshot — mutation during iteration is safe', () => {
56	const r = new SubscriptionRegistry();
57	r.attach('s1', 'c1');
58	r.attach('s2', 'c1');
59	const snap = r.subsForChannel('c1');
60	r.detach('s1', 'c1');
61	expect(snap.slice().sort()).toEqual(['s1', 's2']);
62	expect(r.subsForChannel('c1')).toEqual(['s2']);
63	});
64	});