1 files changed, 79 insertions, 0 deletions
diff --git a/tests/extmod/asyncio_heaplock.py b/tests/extmod/asyncio_heaplock.py
new file mode 100644
index 000000000..8326443f0
--- /dev/null
+++ b/tests/extmod/asyncio_heaplock.py
@@ -0,0 +1,79 @@
+# test that the following do not use the heap:
+# - basic scheduling of tasks
+# - asyncio.sleep_ms
+# - StreamWriter.write, stream is blocked and data to write is a bytes object
+# - StreamWriter.write, when stream is not blocked
+
+import micropython
+
+# strict stackless builds can't call functions without allocating a frame on the heap
+try:
+    # force bytecode (in case we're running with emit=native) and verify
+    # that bytecode-calling-bytecode doesn't allocate
+    @micropython.bytecode
+    def f(x):
+        x and f(x - 1)
+
+    micropython.heap_lock()
+    f(1)
+    micropython.heap_unlock()
+except RuntimeError:
+    # RuntimeError (max recursion depth) not MemoryError because effectively
+    # the recursion depth is at the limit while the heap is locked with
+    # stackless
+    print("SKIP")
+    raise SystemExit
+
+try:
+    import asyncio
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+
+class TestStream:
+    def __init__(self, blocked):
+        self.blocked = blocked
+
+    def write(self, data):
+        print("TestStream.write", data)
+        if self.blocked:
+            return None
+        return len(data)
+
+
+async def task(id, n, t):
+    for i in range(n):
+        print(id, i)
+        await asyncio.sleep_ms(t)
+
+
+async def main():
+    t1 = asyncio.create_task(task(1, 4, 100))
+    t2 = asyncio.create_task(task(2, 2, 250))
+
+    # test scheduling tasks, and calling sleep_ms
+    micropython.heap_lock()
+    print("start")
+    await asyncio.sleep_ms(5)
+    print("sleep")
+    await asyncio.sleep_ms(350)
+    print("finish")
+    micropython.heap_unlock()
+
+    # test writing to a stream, when the underlying stream is blocked
+    s = asyncio.StreamWriter(TestStream(True), None)
+    micropython.heap_lock()
+    s.write(b"12")
+    micropython.heap_unlock()
+
+    # test writing to a stream, when the underlying stream is not blocked
+    buf = bytearray(b"56")
+    s = asyncio.StreamWriter(TestStream(False), None)
+    micropython.heap_lock()
+    s.write(b"34")
+    s.write(buf)
+    micropython.heap_unlock()
+
+
+asyncio.run(main())