js test --prelude ./Tests/prelude.mjs -Xnode --expose-gc

@_spi(JSObject_id) import JavaScriptKit

func testRegressionTestForMisDeallocation() async throws {

// Use Node.js's `--expose-gc` flag to enable manual garbage collection.

guard let gc = JSObject.global.gc.function else {

throw XCTSkip("Missing --expose-gc flag")

}

// Step 1: Create many JSClosure instances

let obj = JSObject()

var closurePointers: Set<UInt32> = []

let numberOfSourceClosures = 10_000

do {

var closures: [JSClosure] = []

for i in 0..<numberOfSourceClosures {

let closure = JSClosure { _ in .undefined }

obj["c\(i)"] = closure.jsValue

closures.append(closure)

// Store

closurePointers.insert(UInt32(UInt(bitPattern: Unmanaged.passUnretained(closure).toOpaque())))

// To avoid all JSClosures having a common address diffs, randomly allocate a new object.

if Bool.random() {

_ = JSObject()

}

}

}

// Step 2: Create many JSObject to make JSObject.id close to Swift heap object address

let minClosurePointer = closurePointers.min() ?? 0

let maxClosurePointer = closurePointers.max() ?? 0

while true {

let obj = JSObject()

if minClosurePointer == obj.id {

break

}

}

// Step 3: Create JSClosure instances and find the one with JSClosure.id == &closurePointers[x]

do {

while true {

let c = JSClosure { _ in .undefined }

if closurePointers.contains(c.id) || c.id > maxClosurePointer {

break

}

// To avoid all JSClosures having a common JSObject.id diffs, randomly allocate a new JS object.

if Bool.random() {

_ = JSObject()

}

}

}

// Step 4: Trigger garbage collection to call the finalizer of the conflicting JSClosure instance

for _ in 0..<100 {

gc()

// Tick the event loop to allow the garbage collector to run finalizers

// registered by FinalizationRegistry.

try await Task.sleep(for: .milliseconds(0))

}

// Step 5: Verify that the JSClosure instances are still alive and can be called

for i in 0..<numberOfSourceClosures {

_ = obj["c\(i)"].function!()

}

}