add test to hello_cancellation (#30)

* add test hello_cancellation

tests/hello/hello_cancellation_test.py

@@ -0,0 +1,56 @@
+import asyncio
+import uuid
+
+import pytest
+from temporalio.client import Client, WorkflowExecutionStatus, WorkflowFailureError
+from temporalio.exceptions import CancelledError
+from temporalio.worker import Worker
+
+from hello.hello_cancellation import (
+    CancellationWorkflow,
+    cleanup_activity,
+    never_complete_activity,
+)
+
+
+async def test_cancel_workflow(client: Client):
+    task_queue_name = str(uuid.uuid4())
+
+    async with Worker(
+        client,
+        task_queue=task_queue_name,
+        workflows=[CancellationWorkflow],
+        activities=[cleanup_activity, never_complete_activity],
+    ):
+        handle = await client.start_workflow(
+            CancellationWorkflow.run,
+            id=(str(uuid.uuid4())),
+            task_queue=task_queue_name,
+        )
+
+        await asyncio.wait_for(
+            wait_for_activity_to_start("never_complete_activity", handle),
+            timeout=5,
+        )
+
+        await handle.cancel()
+
+        with pytest.raises(WorkflowFailureError) as err:
+            await handle.result()
+        assert isinstance(err.value.cause, CancelledError)
+
+        assert WorkflowExecutionStatus.CANCELED == (await handle.describe()).status
+
+
+async def wait_for_activity_to_start(activity_name, handle):
+    while not (await has_activity_started(activity_name, handle)):
+        await asyncio.sleep(0.2)
+
+
+async def has_activity_started(activity_name, handle):
+    pending_activities = (await handle.describe()).raw_description.pending_activities
+    for pending_activity in pending_activities:
+        if pending_activity.activity_type.name == activity_name:
+            return True
+
+    return False