webassembly/asyncio: Support top-level await of asyncio Task and Event.

This change allows doing a top-level await on an asyncio primitive like
Task and Event.

This feature enables a better interaction and synchronisation between
JavaScript and Python, because `api.runPythonAsync` can now be used (called
from JavaScript) to await on the completion of asyncio primitives.

Signed-off-by: Damien George <damien@micropython.org>

2 files changed, 32 insertions, 0 deletions

diff --git a/tests/ports/webassembly/asyncio_top_level_await.mjs b/tests/ports/webassembly/asyncio_top_level_await.mjs
new file mode 100644
index 000000000..d8a9cad42
--- /dev/null
+++ b/tests/ports/webassembly/asyncio_top_level_await.mjs
@@ -0,0 +1,25 @@
+// Test top-level await on asyncio primitives: Task, Event.
+
+const mp = await (await import(process.argv[2])).loadMicroPython();
+
+await mp.runPythonAsync(`
+import asyncio
+
+async def task(event):
+    print("task set event")
+    event.set()
+    print("task sleep")
+    await asyncio.sleep(0.1)
+    print("task end")
+
+event = asyncio.Event()
+t = asyncio.create_task(task(event))
+
+print("top-level wait event")
+await event.wait()
+print("top-level wait task")
+await t
+print("top-level end")
+`);
+
+console.log("finished");
diff --git a/tests/ports/webassembly/asyncio_top_level_await.mjs.exp b/tests/ports/webassembly/asyncio_top_level_await.mjs.exp
new file mode 100644
index 000000000..7232c5d4f
--- /dev/null
+++ b/tests/ports/webassembly/asyncio_top_level_await.mjs.exp
@@ -0,0 +1,7 @@
+top-level wait event
+task set event
+task sleep
+top-level wait task
+task end
+top-level end
+finished