test: Memory leak reproduction for futures

memory-testing/index.mjs

@@ -5,3 +5,4 @@ await createSuite('tokio-future')
 await createSuite('serde')
 await createSuite('tsfn')
 await createSuite('buffer')
+await createSuite('returns-future')

memory-testing/returns-future.mjs

@@ -0,0 +1,26 @@
+import { createRequire } from 'module'
+
+import { displayMemoryUsageFromNode } from './util.mjs'
+
+const initialMemoryUsage = process.memoryUsage()
+
+const require = createRequire(import.meta.url)
+
+const api = require(`./index.node`)
+
+async function main() {
+  let i = 1
+  // eslint-disable-next-line no-constant-condition
+  while (true) {
+    await api.returnsFuture()
+    if (i % 100000 === 0) {
+      displayMemoryUsageFromNode(initialMemoryUsage)
+    }
+    i++
+  }
+}
+
+main().catch((e) => {
+  console.error(e)
+  process.exit(1)
+})

memory-testing/src/lib.rs

@@ -171,3 +171,6 @@ pub fn buffer_pass_through(buffer: Buffer) -> Buffer {
 pub fn array_buffer_pass_through(array_buffer: Uint8Array) -> Uint8Array {
   array_buffer
 }
+
+#[napi]
+pub async fn returns_future() {}