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deepseek-harness/packages/util/deque/tests/deque.spec.ts
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import { describe, expect, it } from 'vitest'
import { Deque } from '@deepseek-ai/dsh-deque'
function backingStorage<T>(deque: Deque<T>): readonly (T | undefined)[] {
// Storage retention is the behavior under test and has no public query API.
return (deque as unknown as { readonly buffer: readonly (T | undefined)[] }).buffer
}
describe('Deque', () => {
it('removes tail-appended entries in FIFO order', () => {
const deque = new Deque<number>()
expect(deque.size).toBe(0)
expect(deque.popFront()).toBeUndefined()
deque.pushBack(1)
deque.pushBack(2)
expect(deque.size).toBe(2)
expect(deque.popFront()).toBe(1)
expect(deque.popFront()).toBe(2)
expect(deque.size).toBe(0)
})
it('prepends entries before the existing head', () => {
const deque = new Deque<number>()
deque.pushBack(3)
deque.pushFront(2)
deque.pushFront(1)
expect([deque.popFront(), deque.popFront(), deque.popFront()]).toEqual([1, 2, 3])
})
it('appends through the array boundary without growing', () => {
const deque = new Deque<number>()
for (let value = 0; value < 8; value += 1) deque.pushBack(value)
for (let value = 0; value < 6; value += 1) expect(deque.popFront()).toBe(value)
for (let value = 8; value <= 16; value += 1) deque.pushBack(value)
for (const value of [6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]) {
expect(deque.popFront()).toBe(value)
}
})
it('preserves order across wrapping, growth, and sparse compaction', () => {
const deque = new Deque<number>()
for (let value = 0; value < 32; value += 1) deque.pushBack(value)
for (let value = 0; value < 24; value += 1) expect(deque.popFront()).toBe(value)
expect(backingStorage(deque)).toHaveLength(16)
for (let value = 32; value < 128; value += 1) deque.pushBack(value)
for (let value = 24; value < 128; value += 1) expect(deque.popFront()).toBe(value)
expect(deque.size).toBe(0)
expect(backingStorage(deque)).toHaveLength(16)
})
it('releases a removed reference before sparse compaction', () => {
const deque = new Deque<object>()
const removed = {}
deque.pushBack(removed)
deque.pushBack({})
expect(deque.popFront()).toBe(removed)
expect(backingStorage(deque)).not.toContain(removed)
expect(backingStorage(deque)).toHaveLength(16)
})
it('drops retained storage and remains reusable after clear', () => {
const deque = new Deque<object>()
const retained = {}
deque.pushBack(retained)
for (let index = 1; index < 64; index += 1) deque.pushBack({ index })
const grownStorage = backingStorage(deque)
deque.clear()
expect(deque.size).toBe(0)
expect(deque.popFront()).toBeUndefined()
expect(backingStorage(deque)).not.toBe(grownStorage)
expect(backingStorage(deque)).not.toContain(retained)
expect(backingStorage(deque)).toHaveLength(16)
const value = {}
deque.pushBack(value)
expect(deque.popFront()).toBe(value)
})
it('uses size to distinguish an undefined entry from an empty deque', () => {
const deque = new Deque<undefined>()
deque.pushBack(undefined)
expect(deque.size).toBe(1)
deque.popFront()
expect(deque.size).toBe(0)
})
})