chore: Add test for module property mutation isolation (#1356)

Author: bergundy

packages/test/src/test-isolation.ts

@@ -64,23 +64,45 @@ test('Global state is isolated and maintained between activations', async (t) =>
   });
 });
 
-export async function propertyMutator(): Promise<void> {
+export async function sdkPropertyMutator(): Promise<void> {
   try {
     (arrayFromPayloads as any).a = 1;
   } catch (err) {
     throw ApplicationFailure.fromError(err);
   }
 }
 
-test('Module state is frozen', withReusableContext, async (t) => {
+test('SDK Module state is frozen', withReusableContext, async (t) => {
   const { createWorker, taskQueue, env } = t.context;
   const worker = await createWorker();
   const err = (await worker.runUntil(
-    t.throwsAsync(env.client.workflow.execute(propertyMutator, { taskQueue, workflowId: randomUUID() }))
+    t.throwsAsync(env.client.workflow.execute(sdkPropertyMutator, { taskQueue, workflowId: randomUUID() }))
   )) as WorkflowFailedError;
   t.is(err.cause?.message, 'Cannot add property a, object is not extensible');
 });
 
+const someArr: number[] = [];
+
+export async function modulePropertyMutator(): Promise<number[]> {
+  someArr.push(1);
+  await sleep(1);
+  someArr.push(2);
+  return someArr;
+}
+
+test('Module state is isolated and maintained between activations', async (t) => {
+  const { createWorker, taskQueue, env } = t.context;
+  const worker = await createWorker();
+  await worker.runUntil(async () => {
+    const [res1, res2] = await Promise.all([
+      env.client.workflow.execute(modulePropertyMutator, { taskQueue, workflowId: randomUUID() }),
+      env.client.workflow.execute(modulePropertyMutator, { taskQueue, workflowId: randomUUID() }),
+    ]);
+    t.deepEqual(res1, [1, 2]);
+    t.deepEqual(res2, [1, 2]);
+  });
+});
+
 export async function sharedGlobalMutator(): Promise<void> {
   try {
     (setTimeout as any).a = 1;