snapshot of https://github.com/tldraw/tldraw.git (main, 2026-09-23; blobs > 131072B omitted)

packages/utils/src/lib/LruCache.test.ts

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+import { LruCache } from './LruCache'
+
+describe('LruCache', () => {
+	it('stores and retrieves values', () => {
+		const cache = new LruCache<string, number>(3)
+		cache.set('a', 1)
+		cache.set('b', 2)
+		expect(cache.get('a')).toBe(1)
+		expect(cache.get('b')).toBe(2)
+		expect(cache.get('c')).toBeUndefined()
+	})
+
+	it('reports size', () => {
+		const cache = new LruCache<string, number>(5)
+		expect(cache.size).toBe(0)
+		cache.set('a', 1)
+		expect(cache.size).toBe(1)
+		cache.set('b', 2)
+		expect(cache.size).toBe(2)
+	})
+
+	it('delete() removes an entry and frees its slot', () => {
+		const cache = new LruCache<string, number>(2)
+		cache.set('a', 1)
+		cache.set('b', 2)
+		expect(cache.delete('a')).toBe(true)
+		expect(cache.delete('a')).toBe(false)
+		expect(cache.has('a')).toBe(false)
+		cache.set('c', 3)
+		expect(cache.get('b')).toBe(2)
+		expect(cache.size).toBe(2)
+	})
+
+	it('has() checks existence without promoting', () => {
+		const cache = new LruCache<string, number>(2)
+		cache.set('a', 1)
+		cache.set('b', 2)
+		expect(cache.has('a')).toBe(true)
+		expect(cache.has('z')).toBe(false)
+
+		// 'a' was not promoted by has(), so adding 'c' should evict 'a'
+		cache.set('c', 3)
+		expect(cache.has('a')).toBe(false)
+	})
+
+	it('evicts the oldest entry when exceeding capacity', () => {
+		const cache = new LruCache<string, number>(2)
+		cache.set('a', 1)
+		cache.set('b', 2)
+		cache.set('c', 3) // should evict 'a'
+
+		expect(cache.get('a')).toBeUndefined()
+		expect(cache.get('b')).toBe(2)
+		expect(cache.get('c')).toBe(3)
+		expect(cache.size).toBe(2)
+	})
+
+	it('get() promotes entry so it is not evicted next', () => {
+		const cache = new LruCache<string, number>(2)
+		cache.set('a', 1)
+		cache.set('b', 2)
+
+		// Access 'a' to promote it; now 'b' is oldest
+		cache.get('a')
+		cache.set('c', 3) // should evict 'b', not 'a'
+
+		expect(cache.get('b')).toBeUndefined()
+		expect(cache.get('a')).toBe(1)
+		expect(cache.get('c')).toBe(3)
+	})
+
+	it('set() on existing key updates value and promotes it', () => {
+		const cache = new LruCache<string, number>(2)
+		cache.set('a', 1)
+		cache.set('b', 2)
+
+		// Update 'a' — promotes it, 'b' becomes oldest
+		cache.set('a', 10)
+		expect(cache.get('a')).toBe(10)
+
+		cache.set('c', 3) // should evict 'b'
+		expect(cache.get('b')).toBeUndefined()
+		expect(cache.get('a')).toBe(10)
+		expect(cache.size).toBe(2)
+	})
+
+	it('evicts entries in insertion order across many inserts', () => {
+		const cache = new LruCache<number, number>(3)
+		for (let i = 0; i < 10; i++) {
+			cache.set(i, i * 10)
+		}
+		// Only the last 3 should remain
+		expect(cache.size).toBe(3)
+		expect(cache.get(7)).toBe(70)
+		expect(cache.get(8)).toBe(80)
+		expect(cache.get(9)).toBe(90)
+		for (let i = 0; i < 7; i++) {
+			expect(cache.has(i)).toBe(false)
+		}
+	})
+})