30 lines
1.4 KiB
TypeScript
30 lines
1.4 KiB
TypeScript
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import { describe, expect, it } from 'vitest'
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import { detachResidual } from '../src/index.ts'
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describe('detachResidual — fd-3 residual detachment', () => {
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it('returns a copy that does NOT share the source frame allocation', () => {
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// Simulate the data handler's state: one large joined frame from
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// Buffer.concat, sliced past its newline to leave a small residual VIEW.
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const joined = Buffer.alloc(1024 * 1024, 0x61) // 1 MiB backing allocation
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joined[512] = 0x0a // a newline partway through
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const residual = joined.subarray(513) // a view onto `joined`'s backing store
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// Before the fix the handler carried this view forward verbatim, pinning the
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// whole 1 MiB `joined` allocation behind a residual that reports far fewer
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// bytes. A right-sized copy must not point back into `joined`.
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const [carried] = detachResidual(residual)
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expect(carried).toBeDefined()
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expect(carried!.length).toBe(residual.length)
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expect(carried!.equals(residual)).toBe(true)
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// The copy's backing store is its own, sized to its content — not the 1 MiB
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// frame. A subarray view would report the source's full byteLength here.
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expect(carried!.buffer.byteLength).toBe(carried!.length)
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expect(carried!.buffer).not.toBe(joined.buffer)
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})
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it('carries nothing forward for an empty residual', () => {
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expect(detachResidual(Buffer.alloc(0))).toEqual([])
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})
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})
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