import { beforeEach, describe, expect, it } from 'vitest'
import { PrefetchManager } from '../queue/prefetch-manager'
describe('PrefetchManager', () => {
let manager: PrefetchManager
beforeEach(() => {
manager = new PrefetchManager(2) // prefetchSize = 2
})
describe('constructor', () => {
it('should initialize with default prefetchSize of 2', () => {
const defaultManager = new PrefetchManager()
expect(defaultManager.getPrefetchSize()).toBe(2)
})
it('should initialize with custom prefetchSize', () => {
const customManager = new PrefetchManager(5)
expect(customManager.getPrefetchSize()).toBe(5)
})
})
describe('addPendingItem', () => {
it('should add item to pending queue', () => {
manager.addPendingItem('item-1')
expect(manager.getPendingCount()).toBe(1)
})
it('should not add duplicate items', () => {
manager.addPendingItem('item-1')
manager.addPendingItem('item-1')
expect(manager.getPendingCount()).toBe(1)
})
it('should add multiple different items', () => {
manager.addPendingItem('item-1')
manager.addPendingItem('item-2')
manager.addPendingItem('item-3')
expect(manager.getPendingCount()).toBe(3)
})
})
describe('getItemsToGenerate', () => {
it('should return up to prefetchSize items when no items are generating', () => {
manager.addPendingItem('item-1')
manager.addPendingItem('item-2')
manager.addPendingItem('item-3')
const items = manager.getItemsToGenerate()
expect(items).toEqual(['item-1', 'item-2'])
})
it('should return fewer items when some are already generating', () => {
manager.addPendingItem('item-1')
manager.addPendingItem('item-2')
manager.addPendingItem('item-3')
manager.incrementGenerating()
const items = manager.getItemsToGenerate()
expect(items).toEqual(['item-1'])
})
it('should return empty array when at prefetchSize capacity', () => {
manager.addPendingItem('item-1')
manager.addPendingItem('item-2')
manager.incrementGenerating()
manager.incrementGenerating()
const items = manager.getItemsToGenerate()
expect(items).toEqual([])
})
it('should return empty array when no pending items', () => {
const items = manager.getItemsToGenerate()
expect(items).toEqual([])
})
it('should return all pending items if less than prefetchSize', () => {
manager.addPendingItem('item-1')
const items = manager.getItemsToGenerate()
expect(items).toEqual(['item-1'])
})
})
describe('incrementGenerating / decrementGenerating', () => {
it('should track generating count correctly', () => {
expect(manager.getGeneratingCount()).toBe(0)
manager.incrementGenerating()
expect(manager.getGeneratingCount()).toBe(1)
manager.incrementGenerating()
expect(manager.getGeneratingCount()).toBe(2)
manager.decrementGenerating()
expect(manager.getGeneratingCount()).toBe(1)
})
it('should not go below zero when decrementing', () => {
manager.decrementGenerating()
expect(manager.getGeneratingCount()).toBe(0)
})
})
describe('removeItem', () => {
it('should remove item from pending queue', () => {
manager.addPendingItem('item-1')
manager.addPendingItem('item-2')
manager.removeItem('item-1')
expect(manager.getPendingCount()).toBe(1)
const items = manager.getItemsToGenerate()
expect(items).toEqual(['item-2'])
})
it('should do nothing when removing non-existent item', () => {
manager.addPendingItem('item-1')
manager.removeItem('non-existent')
expect(manager.getPendingCount()).toBe(1)
})
})
describe('clear', () => {
it('should clear all pending items and reset generating count', () => {
manager.addPendingItem('item-1')
manager.addPendingItem('item-2')
manager.incrementGenerating()
manager.clear()
expect(manager.getPendingCount()).toBe(0)
expect(manager.getGeneratingCount()).toBe(0)
})
})
describe('prefetch workflow', () => {
it('should limit concurrent generations to prefetchSize', () => {
// Add 5 items
for (let i = 1; i <= 5; i++) {
manager.addPendingItem(`item-${i}`)
}
expect(manager.getPendingCount()).toBe(5)
// Get first batch to generate
const batch1 = manager.getItemsToGenerate()
expect(batch1).toEqual(['item-1', 'item-2'])
// Simulate starting generation for batch1
for (const itemId of batch1) {
manager.removeItem(itemId)
manager.incrementGenerating()
}
expect(manager.getPendingCount()).toBe(3)
expect(manager.getGeneratingCount()).toBe(2)
// At capacity - no more items should be returned
expect(manager.getItemsToGenerate()).toEqual([])
// Complete one generation
manager.decrementGenerating()
expect(manager.getGeneratingCount()).toBe(1)
// Now we should get one more item
const batch2 = manager.getItemsToGenerate()
expect(batch2).toEqual(['item-3'])
})
it('should continue prefetching when items complete', () => {
manager.addPendingItem('item-1')
manager.addPendingItem('item-2')
manager.addPendingItem('item-3')
// Start first two
const batch1 = manager.getItemsToGenerate()
for (const itemId of batch1) {
manager.removeItem(itemId)
manager.incrementGenerating()
}
// Complete first
manager.decrementGenerating()
// Should get item-3
const batch2 = manager.getItemsToGenerate()
expect(batch2).toEqual(['item-3'])
})
})
})
