fix: scheduler busy-spins instead of waiting for test completion

run_tests computed the asyncio.wait timeout as elapsed - task_timeout,
which is negative until the deadline, so asyncio.wait returned
immediately and the while loop spun at 100% CPU for the entire run.
Flip it back to time-remaining (task_timeout - elapsed) and clamp it to
at least 1 second so sub-second remainders (truncated to 0 by int())
and already-expired deadlines keep polling instead of spinning.

Present since v0.20.0 (d8e08d1).

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: bugale

pytest_asyncio_cooperative/plugin.py

@@ -200,11 +200,11 @@ async def run_tests(tasks, max_tasks: int, session, item_by_coro):
                 item.enqueue_time = time.time()
             earliest_enqueue_time = min(item.enqueue_time, earliest_enqueue_time)
 
-        time_to_wait = (time.time() - earliest_enqueue_time) - task_timeout
+        time_to_wait = task_timeout - (time.time() - earliest_enqueue_time)
         done, pending = await asyncio.wait(
             tasks,
             return_when=asyncio.FIRST_COMPLETED,
-            timeout=min(30, int(time_to_wait)),
+            timeout=min(30, max(1, int(time_to_wait))),
         )
 
         # Cancel tasks that have taken too long

tests/test_bugs.py

@@ -1,3 +1,6 @@
+import time
+
+
 def test_cached_function_can_handle_kwargs(testdir):
     testdir.makepyfile(
         """
@@ -16,3 +19,24 @@ def test_b(pytestconfig):
     )
     result = testdir.runpytest()
     result.assert_outcomes(passed=2)
+
+
+def test_scheduler_sleeps_while_waiting_for_tests(testdir):
+    """The scheduling loop must block in asyncio.wait until a test completes,
+    not busy-spin with an expired timeout (issue: elapsed/timeout operands were flipped)."""
+    testdir.makepyfile(
+        """
+        import asyncio
+        import pytest
+
+
+        @pytest.mark.asyncio_cooperative
+        async def test_sleep():
+            await asyncio.sleep(3)
+    """
+    )
+    start = time.process_time()
+    result = testdir.runpytest()
+    cpu_time = time.process_time() - start
+    result.assert_outcomes(passed=1)
+    assert cpu_time < 1.5, f"scheduler burned {cpu_time:.1f}s CPU while the only test was sleeping"