test: add tests for new task result and exception behavior

Author: imnotjames

tests/extmod/asyncio_task_cancelled.py

@@ -0,0 +1,83 @@
+# Test cancelling a task
+
+try:
+    import asyncio
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+
+async def task(s, allow_cancel):
+    try:
+        print("task start")
+        await asyncio.sleep(s)
+        print("task done")
+    except asyncio.CancelledError as er:
+        print("task cancel")
+        if allow_cancel:
+            raise er
+
+
+async def task2(allow_cancel):
+    print("task 2")
+    try:
+        await asyncio.create_task(task(0.05, allow_cancel))
+    except asyncio.CancelledError as er:
+        print("task 2 cancel")
+        raise er
+    print("task 2 done")
+
+
+async def main():
+    # Cancel task immediately
+    t = asyncio.create_task(task(2, True))
+    print(t.cancel())
+
+    print("main checking task is cancelled", t.cancelled())
+
+    # Cancel task after it has started
+    t = asyncio.create_task(task(2, True))
+    await asyncio.sleep(0.01)
+    print(t.cancel())
+    print("main sleep")
+    await asyncio.sleep(0.01)
+
+    print("main checking task is cancelled", t.cancelled())
+
+    # Cancel task multiple times after it has started
+    t = asyncio.create_task(task(2, True))
+    await asyncio.sleep(0.01)
+    for _ in range(4):
+        print(t.cancel())
+    print("main sleep")
+    await asyncio.sleep(0.01)
+
+    print("main checking task is cancelled", t.cancelled())
+
+    # Await on a cancelled task
+    print("main wait")
+    try:
+        await t
+    except asyncio.CancelledError:
+        print("main got CancelledError")
+
+    # Cancel task after it has finished
+    t = asyncio.create_task(task(0.01, False))
+    await asyncio.sleep(0.05)
+    print(t.cancel())
+
+    print("main checking task is cancelled", t.cancelled())
+
+    # Nested: task2 waits on task, task2 is cancelled (should cancel task then task2)
+    print("----")
+    t = asyncio.create_task(task2(True))
+    await asyncio.sleep(0.01)
+    print("main cancel")
+    t.cancel()
+    print("main sleep")
+    await asyncio.sleep(0.1)
+
+    print("main checking task 2 is cancelled", t.cancelled())
+
+
+asyncio.run(main())

tests/extmod/asyncio_task_cancelled.py.exp

@@ -0,0 +1,31 @@
+True
+task start
+True
+main sleep
+task cancel
+task start
+True
+True
+True
+True
+main sleep
+task cancel
+main wait
+main got CancelledError
+task start
+task done
+False
+----
+task 2
+task start
+main cancel
+main sleep
+task cancel
+task 2 cancel
+----
+task 2
+task start
+main cancel
+main sleep
+task cancel
+task 2 done

tests/extmod/asyncio_task_exception.py

@@ -0,0 +1,57 @@
+# Test the Task.done() method
+
+try:
+    import asyncio
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+
+async def task(t, exc=None):
+    if t >= 0:
+        await asyncio.sleep(t)
+    if exc:
+        raise exc
+
+
+async def main():
+    # Task that is not done yet raises an InvalidStateError
+    print("=" * 10)
+    t = asyncio.create_task(task(1))
+    await asyncio.sleep(0)
+    try:
+        t.exception()
+        assert False, "Should not get here"
+    except Exception as e:
+        print("Tasks that aren't done yet raise an InvalidStateError:", repr(e))
+
+    # Task that is cancelled raises CancelledError
+    print("=" * 10)
+    t = asyncio.create_task(task(1))
+    t.cancel()
+    await asyncio.sleep(0)
+    try:
+        t.exception()
+        print(t.cancelled())
+        assert False, "Should not get here"
+    except asyncio.CancelledError as e:
+        print("Cancelled tasks cannot retrieve exception:", repr(e))
+
+    # Task that starts, runs and finishes without an exception should return None
+    print("=" * 10)
+    t = asyncio.create_task(task(0.01))
+    await t
+    print("None when no exception:", t.exception())
+
+    # Task that raises immediately should return that exception
+    print("=" * 10)
+    t = asyncio.create_task(task(-1, ValueError))
+    try:
+        await t
+        assert False, "Should not get here"
+    except ValueError as e:
+        pass
+    print("Returned Exception:", repr(t.exception()))
+
+
+asyncio.run(main())

tests/extmod/asyncio_task_exception.py.exp

@@ -0,0 +1,3 @@
+==========
+InvalidStateError('Exception is not set.',)
+==========

tests/extmod/asyncio_task_result.py

@@ -0,0 +1,69 @@
+# Test the Task.done() method
+
+try:
+    import asyncio
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+
+async def task(t, exc=None, ret=None):
+    if t >= 0:
+        await asyncio.sleep(t)
+    if exc:
+        raise exc
+    return ret
+
+
+async def main():
+    # Task that is not done yet raises an InvalidStateError
+    print("=" * 10)
+    t = asyncio.create_task(task(1))
+    await asyncio.sleep(0)
+    try:
+        t.result()
+        assert False, "Should not get here"
+    except Exception as e:
+        print("InvalidStateError if still running:", repr(e))
+
+    # Task that is cancelled raises CancelledError
+    print("=" * 10)
+    t = asyncio.create_task(task(1))
+    t.cancel()
+    await asyncio.sleep(0)
+    try:
+        t.result()
+        assert False, "Should not get here"
+    except asyncio.CancelledError as e:
+        print("CancelledError when retrieving result from cancelled task:", repr(e))
+
+    # Task that raises immediately should raise that exception when calling result
+    print("=" * 10)
+    t = asyncio.create_task(task(-1, ValueError))
+    try:
+        await t
+        assert False, "Should not get here"
+    except ValueError as e:
+        pass
+
+    try:
+        t.result()
+        assert False, "Should not get here"
+    except ValueError as e:
+        print("Error raised when result is attempted on task with error:", repr(e))
+
+    # Task that starts, runs and finishes without an exception or value should return None
+    print("=" * 10)
+    t = asyncio.create_task(task(0.01))
+    await t
+    print("Empty Result should be None:", t.result())
+    assert t.result() is None
+
+    # Task that starts, runs and finishes without exception should return result
+    print("=" * 10)
+    t = asyncio.create_task(task(0.01, None, "hello world"))
+    await t
+    print("Happy path, result is returned:", t.result())
+
+
+asyncio.run(main())

tests/extmod/asyncio_task_result.py.exp

@@ -0,0 +1,10 @@
+==========
+InvalidStateError if still running: InvalidStateError('Result is not ready.',)
+==========
+CancelledError when retrieving result from cancelled task: CancelledError()
+==========
+Error raised when result is attempted on task with error: ValueError()
+==========
+Empty Result should be None: None
+==========
+Happy path, result is returned: hello world