add basic tla execution test

crates/turbopack-tests/tests/execution/turbopack/basic/top-level-await/input/Actions.js

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+// import() doesn't care about whether a module is an async module or not
+const UserApi = import("./UserAPI.js");
+
+export const CreateUserAction = async (name) => {
+  console.log("Creating user", name);
+  // These are normal awaits, because they are in an async function
+  const { createUser } = await UserApi;
+  return await createUser(name);
+};
+
+// You can place import() where you like
+// Placing it at top-level will start loading and evaluating on
+//   module evaluation.
+//   see CreateUserAction above
+//   Here: Connecting to the DB starts when the application starts
+// Placing it inside of an (async) function will start loading
+//   and evaluating when the function is called for the first time
+//   which basically makes it lazy-loaded.
+//   see AlternativeCreateUserAction below
+//   Here: Connecting to the DB starts when AlternativeCreateUserAction
+//         is called
+export const AlternativeCreateUserAction = async (name) => {
+  const { createUser } = await import("./UserAPI.js");
+  return await createUser(name);
+};
+
+// Note: Using await import() at top-level doesn't make much sense
+//       except in rare cases. It will import modules sequentially.

crates/turbopack-tests/tests/execution/turbopack/basic/top-level-await/input/README.md

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+Adapted from webpack
+https://github.com/webpack/webpack/blob/6be4065ade1e252c1d8dcba4af0f43e32af1bdc1/examples/top-level-await/README.md

crates/turbopack-tests/tests/execution/turbopack/basic/top-level-await/input/UserAPI.js

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+import { dbCall } from "./db-connection.js";
+
+export const createUser = async (name) => {
+  const command = `CREATE USER ${name}`;
+  // This is a normal await, because it's in an async function
+  return await dbCall({ command });
+};

crates/turbopack-tests/tests/execution/turbopack/basic/top-level-await/input/db-connection.js

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+const connectToDB = async (url) => {
+  console.log("connecting to db", url);
+  await new Promise((r) => setTimeout(r, 1000));
+};
+
+// This is a top-level-await
+await connectToDB("my-sql://example.com");
+
+export const dbCall = async (data) => {
+  console.log("dbCall", data);
+  // This is a normal await, because it's in an async function
+  await new Promise((r) => setTimeout(r, 100));
+  return "fake data";
+};
+
+export const close = () => {
+  console.log("closes the DB connection");
+};

crates/turbopack-tests/tests/execution/turbopack/basic/top-level-await/input/index.js

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+import { CreateUserAction, AlternativeCreateUserAction } from "./Actions.js";
+
+it("should handle top level await", async () => {
+  const res = await CreateUserAction("John");
+  expect(res).toBe("fake data");
+});
+
+it("should handle top level await (alternative)", async () => {
+  const res = await AlternativeCreateUserAction("John");
+  expect(res).toBe("fake data");
+});