Fixed BlockingScheduler, BackgroundScheduler and GeventScheduler incorrectly waiting MAX_WAIT_TIME when wait_seconds is 0

2 files changed, 21 insertions, 1 deletions

diff --git a/apscheduler/schedulers/blocking.py b/apscheduler/schedulers/blocking.py
index 306860f..2720822 100644
--- a/apscheduler/schedulers/blocking.py
+++ b/apscheduler/schedulers/blocking.py
@@ -25,7 +25,7 @@ class BlockingScheduler(BaseScheduler):
     def _main_loop(self):
         while self.running:
             wait_seconds = self._process_jobs()
-            self._event.wait(wait_seconds or self.MAX_WAIT_TIME)
+            self._event.wait(wait_seconds if wait_seconds is not None else self.MAX_WAIT_TIME)
             self._event.clear()
 
     def wakeup(self):
diff --git a/tests/test_schedulers.py b/tests/test_schedulers.py
index 8f4b40e..ee75ad6 100644
--- a/tests/test_schedulers.py
+++ b/tests/test_schedulers.py
@@ -902,6 +902,12 @@ class TestBlockingScheduler(SchedulerImplementationTestBase):
         return BlockingScheduler()
 
     @pytest.fixture
+    def mock_event_scheduler(self, scheduler):
+        scheduler._event = MagicMock()
+        scheduler._event.clear.side_effect = StopIteration()
+        return scheduler
+
+    @pytest.fixture
     def start_scheduler(self, request, scheduler):
         def cleanup():
             if scheduler.running:
@@ -912,6 +918,20 @@ class TestBlockingScheduler(SchedulerImplementationTestBase):
         thread = Thread(target=scheduler.start)
         return thread.start
 
+    @pytest.mark.parametrize('wait_seconds,expected_wait', [[0, 0], [None, 4294967], [728, 728]],
+                             ids=['zero', 'none', 'positive'])
+    def test_main_loop_wait_seconds_zero(self, mock_event_scheduler, wait_seconds, expected_wait):
+        """Tests that _main_loop() correctly handles the condition where `wait_seconds` is 0."""
+
+        mock_event_scheduler._process_jobs = MagicMock(return_value=wait_seconds)
+        mock_event_scheduler._stopped = False
+        try:  # We need this to break out of the infinite while loop
+            mock_event_scheduler._main_loop()
+        except StopIteration:
+            pass
+
+        mock_event_scheduler._event.wait.assert_called_with(expected_wait)
+
 
 class TestBackgroundScheduler(SchedulerImplementationTestBase):
     @pytest.fixture