wehub-resource-sync
97 lines
3.0 KiB
TypeScript
97 lines
3.0 KiB
TypeScript
/**
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* LRUCache unit tests
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*
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* Covers the eviction guarantees that the resolver relies on:
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* - capacity is enforced (never exceeds max)
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* - LRU ordering: hot keys survive eviction passes
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* - has()/get()/set()/clear() behave like the original Map shape
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* - null values are storable (the fileCache uses null for "failed read")
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*/
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import { describe, it, expect } from 'vitest';
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import { LRUCache } from '../../src/resolution/lru-cache';
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describe('LRUCache', () => {
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it('enforces capacity by evicting the oldest entry on overflow', () => {
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const cache = new LRUCache<string, number>(3);
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cache.set('a', 1);
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cache.set('b', 2);
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cache.set('c', 3);
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cache.set('d', 4); // evicts 'a'
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expect(cache.size).toBe(3);
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expect(cache.has('a')).toBe(false);
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expect(cache.get('a')).toBeUndefined();
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expect(cache.get('b')).toBe(2);
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expect(cache.get('c')).toBe(3);
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expect(cache.get('d')).toBe(4);
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});
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it('promotes touched keys to most-recent so they survive eviction', () => {
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const cache = new LRUCache<string, number>(3);
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cache.set('a', 1);
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cache.set('b', 2);
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cache.set('c', 3);
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// Touch 'a' — it should now be most-recent.
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expect(cache.get('a')).toBe(1);
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cache.set('d', 4); // evicts the LRU, which is now 'b' (not 'a')
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expect(cache.has('a')).toBe(true);
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expect(cache.has('b')).toBe(false);
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expect(cache.has('c')).toBe(true);
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expect(cache.has('d')).toBe(true);
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});
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it('overwriting an existing key refreshes its recency but does not grow size', () => {
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const cache = new LRUCache<string, number>(2);
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cache.set('a', 1);
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cache.set('b', 2);
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cache.set('a', 99); // 'a' is now most-recent
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expect(cache.size).toBe(2);
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expect(cache.get('a')).toBe(99);
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cache.set('c', 3); // should evict 'b', not 'a'
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expect(cache.has('a')).toBe(true);
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expect(cache.has('b')).toBe(false);
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expect(cache.has('c')).toBe(true);
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});
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it('stores null values (used by the file content cache)', () => {
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const cache = new LRUCache<string, string | null>(2);
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cache.set('missing.ts', null);
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expect(cache.has('missing.ts')).toBe(true);
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expect(cache.get('missing.ts')).toBeNull();
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});
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it('clear() resets the cache', () => {
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const cache = new LRUCache<string, number>(3);
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cache.set('a', 1);
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cache.set('b', 2);
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cache.clear();
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expect(cache.size).toBe(0);
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expect(cache.has('a')).toBe(false);
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});
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it('rejects non-positive capacity', () => {
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expect(() => new LRUCache(0)).toThrow();
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expect(() => new LRUCache(-1)).toThrow();
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expect(() => new LRUCache(NaN)).toThrow();
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});
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it('stays bounded under heavy churn (regression for OOM scenario)', () => {
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const cache = new LRUCache<string, number>(100);
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for (let i = 0; i < 10_000; i++) {
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cache.set(`key${i}`, i);
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}
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expect(cache.size).toBe(100);
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// The last 100 keys should still be present, the rest evicted.
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expect(cache.has('key9999')).toBe(true);
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expect(cache.has('key9900')).toBe(true);
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expect(cache.has('key0')).toBe(false);
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});
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});
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