Add tests for the AsyncFunction

src/async-function.ts

@@ -0,0 +1,11 @@
+const AsyncFunction = Object.getPrototypeOf(async () => {}).constructor
+
+type AsyncFunctionArguments = {[key: string]: any}
+
+export async function callAsyncFunction(
+  args: AsyncFunctionArguments,
+  source: string
+): Promise<any> {
+  const fn = new AsyncFunction(...Object.keys(args), source)
+  return fn(...Object.values(args))
+}