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deepseek-harness/packages/experimental/webworker-runtime/tests/compile/transform.spec.ts
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32 KiB
TypeScript

/**
* Semantic check of the worker module transform (`src/compile/transform.ts`): what the
* emitted CommonJS body looks like for each module form, how suspension points
* are rewritten, that line numbers survive, which forms are refused, and that
* every covered trap form stays fixed.
*
* Scope boundary: this file checks the transform itself; the pack-time loop
* around it is covered end-to-end by the packer's `image-loadable.spec.ts`.
* Emitted-code assertions are deliberately written against substrings
* of the real output rather than whole-file goldens: a golden would fail on every
* helper reordering, which is not the contract. The contract is the observable
* one — the code parses as script, publishes the right bindings, keeps line
* count, and routes suspension through `__als`.
*
* The trap cases are module forms that break a boot when the transform
* mishandles them. Five traps cannot recur while the AST pass is the parser,
* but they stay checked because a future parser swap could reintroduce them.
*/
import { expect, test } from 'vitest'
import { parse } from 'acorn'
import { lowerModuleSource } from '../../src/compile/transform.ts'
import { LOWERING_VERSION, WRAPPER_PARAMS } from '../../src/image-layout.ts'
/**
* Lower one probe module the way the packer does — the transform's only caller.
* @param source - Module source under test.
* @param path - Path the diagnostics name.
* @returns The emitted body.
*/
const transformModule = (source: string, path = 'probe.js'): string =>
lowerModuleSource({ filename: path, source }).code
/** Register one comparison as its own case, serialized at call time. */
const check = (label: string, actual: unknown, expected: unknown): void => {
const [seen, wanted] = [JSON.stringify(actual), JSON.stringify(expected)]
test(label, () => { expect(seen).toBe(wanted) })
}
/** Assert a substring is present in an emitted body. */
const contains = (label: string, code: string, needle: string): void => {
test(label, () => { expect(code).toContain(needle) })
}
/** Assert a substring is absent (used for "must survive untouched" cases). */
const lacks = (label: string, code: string, needle: string): void => {
test(label, () => { expect(code).not.toContain(needle) })
}
/** @returns The error message of a refused transform, or undefined when it succeeded. */
const refusal = (source: string, path = 'probe.js'): string | undefined => {
try {
transformModule(source, path)
return undefined
} catch (reason) {
return (reason as Error).message
}
}
/** Assert the transform refuses a source and names the reason. */
const refuses = (label: string, source: string, fragment: string): void => {
const message = refusal(source)
test(label, () => { expect(message).toContain(fragment) })
}
/**
* The wrapper contract, applied for real: compile the body with the declared
* parameters and run it. This is the same `new Function` shape the loader uses
* (module-loader.ts), so a body that compiles here compiles there.
* @param code - Emitted CommonJS body.
* @param require - Module resolver the body's `require` calls reach.
* @param als - Suspension runtime bound to `__als`.
* @returns The populated `exports` object.
*/
function runBody(
code: string,
require: (specifier: string) => unknown = () => ({}),
als?: unknown,
): Record<string, unknown> {
const exports: Record<string, unknown> = {}
const module = { exports }
// eslint-disable-next-line @typescript-eslint/no-implied-eval -- the wrapper contract under test is a `new Function` body
const factory = new Function(...WRAPPER_PARAMS, code) as (...args: unknown[]) => void
factory(exports, require, module, '/vfs/probe.js', '/vfs', { url: 'file:///vfs/probe.js' }, als)
return exports
}
/** Every emitted body must parse as a script — the transform's own exit gate, re-checked here. */
const parsesAsScript = (label: string, code: string): void => {
test(label, () => {
expect(() => parse(code, { ecmaVersion: 'latest', sourceType: 'script', allowAwaitOutsideFunction: false })).not.toThrow()
})
}
// ---------------------------------------------------------------------------
// 1. The published contract: the three names the packer and loader share.
// ---------------------------------------------------------------------------
check('LOWERING_VERSION is a non-empty string', typeof LOWERING_VERSION === 'string' && LOWERING_VERSION.length > 0, true)
check('WRAPPER_PARAMS is the frozen 7-parameter shape', [...WRAPPER_PARAMS], [
'exports', 'require', 'module', '__filename', '__dirname', '__dsh$meta', '__als',
])
// The wrapper signature is a contract with the loader's `new Function`, so the
// parameters must be valid identifiers in that position.
check(
'every wrapper parameter is a usable identifier',
(() => {
try {
// eslint-disable-next-line @typescript-eslint/no-implied-eval -- proves the parameter names compile where the loader uses them
new Function(...WRAPPER_PARAMS, 'return 0')
return true
} catch {
return false
}
})(),
true,
)
// ---------------------------------------------------------------------------
// 2. lowerModuleSource: the packer face. `lowered` is the pack-time decision.
// ---------------------------------------------------------------------------
{
const esm = lowerModuleSource({ filename: 'node_modules/p/index.js', source: 'export const a = 1\n' })
check('lowered=true for a module that needed rewriting', esm.lowered, true)
check('lowered code differs from source', esm.code !== 'export const a = 1\n', true)
// Plain CommonJS with no suspension point is the "pack as-is" case: the
// collector relies on this to leave 1693-odd entries untouched.
const plain = 'module.exports = 1\n'
const cjs = lowerModuleSource({ filename: 'node_modules/p/legacy.cjs', source: plain })
check('lowered=false for plain CommonJS', cjs.lowered, false)
check('unlowered code is the input verbatim', cjs.code, plain)
// A CommonJS body that still contains a suspension point must be rewritten:
// `await` inside a function is the ALS protocol's business even with no ESM.
const cjsAwait = lowerModuleSource({
filename: 'node_modules/p/async.cjs',
source: 'module.exports = async () => { await 1 }\n',
})
check('lowered=true for CommonJS carrying a suspension point', cjsAwait.lowered, true)
contains('CommonJS await still routes through __als', cjsAwait.code, '__als.pause(')
// `lowered` must agree with the code/source comparison by construction.
check('lowered mirrors code !== source', cjsAwait.lowered, cjsAwait.code !== 'module.exports = async () => { await 1 }\n')
}
{
const direct = lowerModuleSource({
filename: 'node_modules/p/direct.js',
source: "import { createRequire } from 'node:module'\ncreateRequire(import.meta.url)('@xterm/headless')\n",
})
check('literal createRequire call is a module request', direct.moduleRequests, ['node:module', '@xterm/headless'])
const assigned = lowerModuleSource({
filename: 'node_modules/p/assigned.js',
source: "import { createRequire as makeRequire } from 'node:module'\nconst localRequire = makeRequire(import.meta.url)\nlocalRequire('p')\n",
})
check('literal call through a createRequire binding is a module request', assigned.moduleRequests, ['node:module', 'p'])
}
// ---------------------------------------------------------------------------
// 3. Import forms.
// ---------------------------------------------------------------------------
{
// Side-effect import: a bare require, nothing bound.
const code = transformModule("import './side-effect.js'\n", 'probe.js')
contains('side-effect import becomes a bare require', code, 'require("./side-effect.js")')
parsesAsScript('side-effect import', code)
const requested: string[] = []
runBody(code, (specifier) => {
requested.push(specifier)
return {}
})
check('side-effect import actually requires at run time', requested, ['./side-effect.js'])
}
{
// Named imports are snapshots (CommonJS destructuring semantics), which is the
// documented, accepted divergence from ESM live bindings on the import side.
const code = transformModule("import { a, b as c } from 'p'\nexport const out = [a, c]\n", 'probe.js')
parsesAsScript('named imports', code)
const exports = runBody(code, () => ({ a: 1, b: 2 }))
check('named import binds by imported name, honouring the alias', exports.out, [1, 2])
}
{
// Default and namespace imports go through the two interop helpers, which must
// agree with `Loader.unwrapExports` on the `__esModule` convention.
const code = transformModule("import d from 'p'\nimport * as ns from 'q'\nexport const seen = [d, ns.x, ns.default]\n", 'probe.js')
parsesAsScript('default and namespace imports', code)
// An `__esModule` module: default comes from `.default`, namespace passes through.
const esModule = { __esModule: true, default: 'D', x: 'X' }
const withEsm = runBody(code, () => esModule)
check('default import of an __esModule module reads .default', (withEsm.seen as unknown[])[0], 'D')
// A plain CommonJS module: the module object *is* the default, and the
// namespace gains a `default` key pointing at it.
const plain = { x: 'X' }
const withCjs = runBody(code, () => plain)
check('default import of plain CommonJS is the module object', (withCjs.seen as unknown[])[0], plain)
check('namespace of plain CommonJS keeps the named key', (withCjs.seen as unknown[])[1], 'X')
check('namespace of plain CommonJS synthesizes default', (withCjs.seen as unknown[])[2], plain)
}
// ---------------------------------------------------------------------------
// 4. Export forms, including the live-binding contract.
// ---------------------------------------------------------------------------
{
const code = transformModule('export const a = 1\nexport function f() {}\nexport class K {}\n', 'probe.js')
parsesAsScript('exported declarations', code)
contains('module bodies get the __esModule marker', code, '__esModule')
contains('use strict is part of the prologue', code, '"use strict"')
const exports = runBody(code)
check('exported const is published', exports.a, 1)
check('exported function is published', typeof exports.f, 'function')
check('exported class is published', typeof exports.K, 'function')
}
{
// Local exports are getters, so a later assignment is observable through
// `exports` — the ESM live-binding property.
const code = transformModule('export let counter = 0\nexport function bump() { counter += 1 }\n', 'probe.js')
parsesAsScript('live binding', code)
const exports = runBody(code)
check('live binding starts at its initializer', exports.counter, 0)
;(exports.bump as () => void)()
check('live binding observes a later assignment', exports.counter, 1)
// A getter, not a data property: this is what makes the above work.
check(
'exported local is an accessor',
typeof Object.getOwnPropertyDescriptor(exports, 'counter')?.get,
'function',
)
}
{
// Trap 4: a multi-declarator export publishes every binding.
const code = transformModule('export const a = 1, b = 2\n', 'probe.js')
parsesAsScript('multi-declarator export', code)
const exports = runBody(code)
check('multi-declarator export publishes every binding', [exports.a, exports.b], [1, 2])
}
{
// Destructuring exports exercise the pattern walker (object, array, rest,
// default) — every branch of `declaredBindings`.
const code = transformModule(
'export const { p, q: renamed, ...restObj } = { p: 1, q: 2, z: 3 }\n'
+ 'export const [first, , third = 30, ...restArr] = [10, 20, undefined, 40, 50]\n',
'probe.js',
)
parsesAsScript('destructuring exports', code)
const exports = runBody(code)
check('object pattern export', [exports.p, exports.renamed], [1, 2])
check('object rest export', exports.restObj, { z: 3 })
check('array pattern export with hole', [exports.first, exports.third], [10, 30])
check('array rest export', exports.restArr, [40, 50])
// The renamed target is what is published; the source key is not a binding.
check('object pattern publishes the local name, not the source key', 'q' in exports, false)
}
{
const code = transformModule('const x = 1\nexport { x as y }\n', 'probe.js')
parsesAsScript('local export clause', code)
const exports = runBody(code)
check('local export clause publishes under the exported name', exports.y, 1)
check('local export clause does not publish the local name', 'x' in exports, false)
}
{
// Re-export clause: a getter onto the required module, so it also stays live.
const module: Record<string, unknown> = { a: 1 }
const code = transformModule("export { a, a as aliased } from 'p'\n", 'probe.js')
parsesAsScript('re-export clause', code)
const exports = runBody(code, () => module)
check('re-export publishes the name', exports.a, 1)
check('re-export publishes the alias', exports.aliased, 1)
module.a = 2
check('re-export is live against the source module', exports.a, 2)
}
{
// `export *` copies enumerable keys, skips `default`, and must not clobber an
// existing local export.
const code = transformModule("export const own = 'local'\nexport * from 'p'\n", 'probe.js')
parsesAsScript('export all', code)
const exports = runBody(code, () => ({ extra: 'E', default: 'D', own: 'theirs' }))
check('export * copies named keys', exports.extra, 'E')
check('export * skips default', 'default' in exports, false)
check('export * does not overwrite an existing export', exports.own, 'local')
}
{
const code = transformModule("export * as ns from 'p'\n", 'probe.js')
parsesAsScript('export all as namespace', code)
const exports = runBody(code, () => ({ x: 1 }))
check('export * as ns publishes a namespace object', (exports.ns as Record<string, unknown>).x, 1)
}
{
const code = transformModule('export default 42\n', 'probe.js')
parsesAsScript('default export value', code)
check('default export lands on exports.default', runBody(code).default, 42)
}
{
// Documented cost: the function name stops being a module-scope binding, but
// the named function expression can still refer to itself.
const code = transformModule('export default function self(n) { return n <= 0 ? 0 : self(n - 1) }\n', 'probe.js')
parsesAsScript('default export function', code)
const fn = runBody(code).default as (n: number) => number
check('default-exported function keeps self-reference', fn(3), 0)
}
{
const code = transformModule("export { x as default } from 'p'\n", 'probe.js')
parsesAsScript('re-export as default', code)
check('re-export as default publishes default', runBody(code, () => ({ x: 'D' })).default, 'D')
}
// ---------------------------------------------------------------------------
// 5. import.meta and dynamic import.
// ---------------------------------------------------------------------------
{
const code = transformModule('export const here = import.meta.url\n', 'probe.js')
parsesAsScript('import.meta', code)
contains('import.meta becomes the wrapper parameter', code, '__dsh$meta')
check('import.meta.url resolves through the wrapper', runBody(code).here, 'file:///vfs/probe.js')
}
{
// Dynamic import routes through the same require chain (which is what makes
// typert-loader's absolute-path `import()` land on the VFS resolver), and the
// result is namespace-shaped.
const code = transformModule("export const load = () => import('p')\n", 'probe.js')
parsesAsScript('dynamic import', code)
contains('dynamic import becomes the helper call', code, '__dsh$dynImport')
const load = runBody(code, () => ({ x: 1 })).load as () => Promise<Record<string, unknown>>
const namespace = await load()
check('dynamic import resolves to a namespace object', namespace.x, 1)
check('dynamic import namespace has a default', 'default' in namespace, true)
}
// ---------------------------------------------------------------------------
// 6. Suspension points. Behaviour is checked against a recording runtime, so
// these assert the protocol shape rather than re-testing als-runtime.
// ---------------------------------------------------------------------------
/** A recording stand-in for the ALS runtime: proves the emitted calls happen in order. */
function recordingAls(): { als: Record<string, unknown>; calls: string[] } {
const calls: string[] = []
const als = {
pause: (value: unknown) => {
calls.push('pause')
return Promise.resolve(value).then(
settled => ({ ok: true, value: settled, snapshot: 'S' }),
(error: unknown) => ({ ok: false, error, snapshot: 'S' }),
)
},
resume: (token: { ok: boolean; value?: unknown; error?: unknown }) => {
calls.push('resume')
if (token.ok) return token.value
throw token.error
},
snapshot: () => {
calls.push('snapshot')
return 'S'
},
afterYield: (_snapshot: unknown, sent: unknown) => {
calls.push('afterYield')
return sent
},
iterator: (value: unknown) => {
calls.push('iterator')
const source = value as Record<PropertyKey, unknown>
const asyncFactory = source[Symbol.asyncIterator] as (() => AsyncIterator<unknown>) | undefined
if (typeof asyncFactory === 'function') return asyncFactory.call(source)
const syncFactory = source[Symbol.iterator] as () => Iterator<unknown, unknown>
const inner = syncFactory.call(source)
return {
next: async (...args: unknown[]) => {
const step = inner.next(...args as [unknown])
return { done: step.done ?? false, value: await step.value }
},
return: async (sent?: unknown) => {
const step = inner.return?.(sent) ?? { done: true, value: undefined }
return { done: step.done ?? true, value: await step.value }
},
}
},
close: async (iterator: AsyncIterator<unknown>) => {
calls.push('close')
return iterator.return?.(undefined)
},
}
return { als, calls }
}
{
const code = transformModule('export const run = async () => await 7\n', 'probe.js')
parsesAsScript('await rewrite', code)
contains('await is wrapped in resume(await pause(', code, '__als.resume(await __als.pause(')
const { als, calls } = recordingAls()
const run = runBody(code, () => ({}), als).run as () => Promise<number>
check('await still yields its value', await run(), 7)
check('await goes pause-then-resume', calls, ['pause', 'resume'])
}
{
// The rejection path is the half that a naive "snapshot on success" rewrite
// gets wrong, so it is checked as its own case.
const code = transformModule(
"export const run = async () => { try { await Promise.reject(new Error('boom')) } catch (reason) { return `caught:${reason.message}` } }\n",
'probe.js',
)
parsesAsScript('await rejection', code)
const { als, calls } = recordingAls()
const run = runBody(code, () => ({}), als).run as () => Promise<string>
check('rejection surfaces through resume', await run(), 'caught:boom')
check('rejection path also goes pause-then-resume', calls, ['pause', 'resume'])
}
{
// for-await desugars to an explicit loop; `return()` must run only on abrupt
// completion, which is the language rule. The two
// completion paths need two different loop bodies, so they are separate cases.
const plain = 'export const run = async (src) => { const seen = []\n'
+ 'for await (const item of src) { seen.push(item) }\n'
+ 'return seen }\n'
const code = transformModule(plain, 'probe.js')
parsesAsScript('for-await', code)
contains('for-await uses the iterator helper', code, '__als.iterator(')
contains('for-await closes on abrupt completion', code, '__als.close(')
/** An async iterable counting up to `n`, rebuilt per case so state cannot leak. */
const counting = (n: number): unknown => ({
[Symbol.asyncIterator]: () => {
let emitted = 0
return {
next: () => Promise.resolve(
emitted < n ? { done: false, value: ++emitted } : { done: true, value: undefined },
),
}
},
})
// Normal completion: the iterator is exhausted, so `return()` must NOT run.
const { als, calls } = recordingAls()
const run = runBody(code, () => ({}), als).run as (src: unknown) => Promise<number[]>
check('for-await over an async source collects values', await run(counting(2)), [1, 2])
check('normal completion does not close the iterator', calls.includes('close'), false)
// Abrupt completion (break), and a sync source whose values are promises
// (async-from-sync): close must run exactly once.
const breaking = 'export const run = async (src) => { const seen = []\n'
+ 'for await (const item of src) { seen.push(item); if (item === 2) break }\n'
+ 'return seen }\n'
const breakingCode = transformModule(breaking, 'probe.js')
parsesAsScript('for-await with break', breakingCode)
const { als: als2, calls: calls2 } = recordingAls()
const run2 = runBody(breakingCode, () => ({}), als2).run as (src: unknown) => Promise<number[]>
const syncSource = {
[Symbol.iterator]: () => [Promise.resolve(1), Promise.resolve(2), Promise.resolve(3)][Symbol.iterator](),
}
check('for-await accepts a sync source of promises', await run2(syncSource), [1, 2])
check('break closes the iterator exactly once', calls2.filter(name => name === 'close').length, 1)
}
{
// Destructuring in the loop head goes through the same binding path.
const code = transformModule(
'export const run = async (src) => { const seen = []\nfor await (const { v } of src) seen.push(v)\nreturn seen }\n',
'probe.js',
)
parsesAsScript('for-await destructuring', code)
const { als } = recordingAls()
const run = runBody(code, () => ({}), als).run as (src: unknown) => Promise<number[]>
check('for-await destructures each step', await run([{ v: 1 }, { v: 2 }]), [1, 2])
}
{
// A non-block body must still be wrapped, or the emitted loop would swallow
// the following statement.
const code = transformModule(
'export const run = async (src) => { let sum = 0\nfor await (const n of src) sum += n\nreturn sum }\n',
'probe.js',
)
parsesAsScript('for-await single-statement body', code)
const { als } = recordingAls()
const run = runBody(code, () => ({}), als).run as (src: unknown) => Promise<number>
check('for-await with a non-block body runs correctly', await run([1, 2, 3]), 6)
}
{
// `yield` in an async generator: the snapshot is taken before suspending and
// the consumer's sent value comes back through afterYield.
const code = transformModule(
'export async function* gen() { const got = yield 1\nyield got * 2 }\n',
'probe.js',
)
parsesAsScript('yield rewrite', code)
contains('yield is wrapped in afterYield(snapshot(), yield ...)', code, '__als.afterYield(__als.snapshot(),yield ')
const { als, calls } = recordingAls()
const gen = runBody(code, () => ({}), als).gen as () => AsyncGenerator<number, void, number>
const iterator = gen()
check('first yield produces its value', (await iterator.next(0)).value, 1)
check('sent value returns through afterYield', (await iterator.next(21)).value, 42)
check('yield recorded snapshot and afterYield', calls.filter(name => name === 'afterYield').length >= 1, true)
}
{
// Statement-position `yield*` desugars into a forwarding loop.
const code = transformModule(
'export async function* outer(inner) { yield* inner\nyield "tail" }\n',
'probe.js',
)
parsesAsScript('yield* rewrite', code)
const { als } = recordingAls()
const outer = runBody(code, () => ({}), als).outer as (inner: unknown) => AsyncGenerator<unknown, void, unknown>
const collected: unknown[] = []
for await (const value of outer(['a', 'b'])) collected.push(value)
check('yield* forwards inner values then continues', collected, ['a', 'b', 'tail'])
}
// ---------------------------------------------------------------------------
// 7. Line numbers. The debugging contract: a stack frame in a transformed body
// points at the same line as the artifact it came from.
// ---------------------------------------------------------------------------
/** @returns Line count of a string, counting a trailing newline's line as the last. */
const lineCount = (text: string): number => text.split('\n').length
{
// The prologue is emitted without a trailing newline, so a transformed body
// has exactly as many lines as its source. Anything else is line drift.
const cases: Array<{ readonly label: string; readonly source: string }> = [
{ label: 'imports and exports', source: "import { a } from 'p'\n\nexport const b = a\n\nexport default b\n" },
{ label: 'await in a function', source: 'export const f = async () => {\n const v = await g()\n return v\n}\n' },
{
label: 'for-await (body re-emitted)',
source: 'export const f = async (src) => {\n for await (const x of src) {\n use(x)\n }\n done()\n}\n',
},
{
label: 'yield* (statement desugared)',
source: 'export async function* f(inner) {\n yield* inner\n after()\n}\n',
},
{ label: 'export * with following lines', source: "export * from 'p'\nconst tail = 1\nexport { tail }\n" },
{ label: 'multi-line import clause', source: "import {\n a,\n b,\n} from 'p'\nexport const out = [a, b]\n" },
]
for (const { label, source } of cases) {
const code = transformModule(source, 'probe.js')
check(`line count survives: ${label}`, lineCount(code), lineCount(source))
}
}
// ---------------------------------------------------------------------------
// 8. Refusals. Every one of these is a form the transform must reject loudly
// rather than emit something that breaks later.
// ---------------------------------------------------------------------------
refuses('top-level await is refused', 'export const a = 1\nawait boot()\n', 'top-level await')
refuses('top-level for-await is refused', 'for await (const x of src) use(x)\n', 'top-level for-await')
refuses(
'labeled for-await is refused',
'export const f = async (src) => { outer: for await (const x of src) { break outer } }\n',
'labeled for-await',
)
refuses(
'import attributes are refused',
"import data from './d.json' with { type: 'json' }\n",
'import attributes',
)
refuses(
'value-position yield* is refused',
'export async function* f(inner) { const v = yield* inner\nuse(v) }\n',
'yield* is only supported as a statement',
)
refuses(
'assignment around yield* is refused, never silently dropped',
'export async function* f(inner) { let v\nv = yield* inner\nuse(v) }\n',
'yield* is only supported as the whole statement expression',
)
refuses(
'a call around yield* is refused, never silently dropped',
'export async function* f(inner) { use(yield* inner) }\n',
'yield* is only supported as the whole statement expression',
)
refuses(
'already-lowered source is refused',
'const x = __als.pause(1)\n',
'already lowered',
)
refuses('unparseable source is refused', 'export const = \n', 'parse failed')
{
// A refusal must name the file and the line, which is what makes a build
// failure actionable.
const message = refusal('export const a = 1\n\n\nawait boot()\n', 'node_modules/p/index.js')
check('refusal names the file', message?.includes('node_modules/p/index.js'), true)
check('refusal names the offending line', message?.includes(':4'), true)
}
// ---------------------------------------------------------------------------
// 9. Trap regressions. Each case is a module form that breaks a boot when the
// transform mishandles it; the AST pass must keep them fixed.
// ---------------------------------------------------------------------------
{
// Trap 1: a file with no module syntax can still contain a dynamic import. A
// transform that skips such files would leave it unrewritten, and it would
// escape to the host engine's parser.
const code = transformModule("module.exports = () => import('./x.js')\n", 'probe.js')
contains('trap 1: dynamic import in a CommonJS file is still rewritten', code, '__dsh$dynImport')
parsesAsScript('trap 1', code)
}
{
// Trap 2: `export {}` is a bundler module marker and must be removed before
// `new Function` parses the body. The needle is the keyword in statement
// position, since `exports.` in the prologue legitimately contains the same
// letters.
const code = transformModule('export {};\n', 'probe.js')
lacks('trap 2: bare export {} is removed', code, 'export {')
lacks('trap 2: no export keyword survives', code, 'export;')
parsesAsScript('trap 2', code)
check('trap 2: emitted body still marks __esModule', '__esModule' in runBody(code), true)
}
{
// Trap 3/4: every declarator is published, including declarations without an
// initializer.
const code = transformModule('export let x, y\nexport const set = () => { x = 1; y = 2 }\n', 'probe.js')
parsesAsScript('trap 3', code)
const exports = runBody(code)
;(exports.set as () => void)()
check('trap 3: every declarator is exported, initializer or not', [exports.x, exports.y], [1, 2])
}
{
// Trap 6: a block comment before a class member named `import` must not be
// treated as a dynamic import. Renaming `EntryTree.prototype.import` breaks
// the loading chain at `Entry._init` with
// "this.parent.tree.import is not a function".
const source = 'export class A {\n /** doc */ import(name) { return name }\n}\n'
const code = transformModule(source, 'probe.js')
lacks('trap 6: a method named import is not rewritten', code, '__dsh$dynImport')
parsesAsScript('trap 6', code)
const A = runBody(code).A as new () => { import: (name: string) => string }
check('trap 6: the method is still callable under its own name', new A().import('kept'), 'kept')
}
{
// Trap 7: a comment between `export` and the declaration keyword must not
// hide the declaration; refusing zod's
// `export /*@__NO_SIDE_EFFECTS__*/ function` takes 30-odd roster rows down
// with it.
const code = transformModule('export /*@__NO_SIDE_EFFECTS__*/ function $constructor(x) { return x }\n', 'probe.js')
parsesAsScript('trap 7', code)
check('trap 7: export with an interposed comment still publishes', typeof runBody(code).$constructor, 'function')
}
{
// `new.target` is also a MetaProperty. Replacing every MetaProperty would
// make `new.target === Cls` permanently false, silently disabling
// abstract-seam guards in `jobs` and `llm`.
const source = 'export class Base {\n constructor() { this.direct = new.target === Base }\n}\n'
const code = transformModule(source, 'probe.js')
contains('trap 8: new.target survives verbatim', code, 'new.target')
lacks('trap 8: new.target is not replaced by the meta parameter', code, '__dsh$meta')
parsesAsScript('trap 8', code)
const Base = runBody(code).Base as new () => { direct: boolean }
class Derived extends Base {}
check('trap 8: new.target compares true for a direct construction', new Base().direct, true)
check('trap 8: new.target compares false for a subclass', new Derived().direct, false)
}
{
// Shebang handling: `#!` is only legal at offset 0, which the prologue
// occupies. It is commented out in place so both offsets and the line count
// stay put.
const source = '#!/usr/bin/env node\nexport const main = 1\n'
const code = transformModule(source, 'probe.js')
lacks('shebang is not left in the emitted body', code, '#!')
parsesAsScript('shebang', code)
check('shebang: line count still survives', lineCount(code), lineCount(source))
check('shebang: the module still works', runBody(code).main, 1)
}
{
// The exit gate itself: the transform re-parses its own output as a script.
// Any leftover module syntax or mis-spliced interval fails there, not at load.
// Re-checked here over a source that exercises several edits at once.
const source = "import a from 'p'\nexport * from 'q'\nexport const f = async () => { for await (const x of a) { await x } }\n"
parsesAsScript('exit gate over combined edits', transformModule(source, 'probe.js'))
}
// ---------------------------------------------------------------------------
// 10. Caching: the transform memoizes by source text, and the cache must not
// leak a different file's result.
// ---------------------------------------------------------------------------
{
const source = 'export const cached = 1\n'
const first = transformModule(source, 'a.js')
const second = transformModule(source, 'b.js')
check('identical sources return the identical cached body', first === second, true)
// Distinct sources must not collide.
check(
'distinct sources produce distinct bodies',
transformModule('export const other = 2\n', 'c.js') !== first,
true,
)
}