Issue 24178: support 'async with' for asyncio locks.

Lib/test/test_asyncio/test_pep492.py

@@ -0,0 +1,68 @@
+"""Tests support for new syntax introduced by PEP 492."""
+
+import unittest
+from unittest import mock
+
+import asyncio
+from asyncio import test_utils
+
+
+class BaseTest(test_utils.TestCase):
+
+    def setUp(self):
+        self.loop = asyncio.BaseEventLoop()
+        self.loop._process_events = mock.Mock()
+        self.loop._selector = mock.Mock()
+        self.loop._selector.select.return_value = ()
+        self.set_event_loop(self.loop)
+
+
+class LockTests(BaseTest):
+
+    def test_context_manager_async_with(self):
+        primitives = [
+            asyncio.Lock(loop=self.loop),
+            asyncio.Condition(loop=self.loop),
+            asyncio.Semaphore(loop=self.loop),
+            asyncio.BoundedSemaphore(loop=self.loop),
+        ]
+
+        async def test(lock):
+            await asyncio.sleep(0.01, loop=self.loop)
+            self.assertFalse(lock.locked())
+            async with lock as _lock:
+                self.assertIs(_lock, None)
+                self.assertTrue(lock.locked())
+                await asyncio.sleep(0.01, loop=self.loop)
+                self.assertTrue(lock.locked())
+            self.assertFalse(lock.locked())
+
+        for primitive in primitives:
+            self.loop.run_until_complete(test(primitive))
+            self.assertFalse(primitive.locked())
+
+    def test_context_manager_with_await(self):
+        primitives = [
+            asyncio.Lock(loop=self.loop),
+            asyncio.Condition(loop=self.loop),
+            asyncio.Semaphore(loop=self.loop),
+            asyncio.BoundedSemaphore(loop=self.loop),
+        ]
+
+        async def test(lock):
+            await asyncio.sleep(0.01, loop=self.loop)
+            self.assertFalse(lock.locked())
+            with await lock as _lock:
+                self.assertIs(_lock, None)
+                self.assertTrue(lock.locked())
+                await asyncio.sleep(0.01, loop=self.loop)
+                self.assertTrue(lock.locked())
+            self.assertFalse(lock.locked())
+
+        for primitive in primitives:
+            self.loop.run_until_complete(test(primitive))
+            self.assertFalse(primitive.locked())
+
+
+if __name__ == '__main__':
+    unittest.main()