chore: fix flaky unit tests: tests/unittests/flows/llm_flows/test_functions_simple.py

original tests assert too strict time boundary, now we only assert the parallel execution time should be less than sequential execution time PiperOrigin-RevId: 800563929

Author: seanzhougoogle

tests/unittests/flows/llm_flows/test_functions_simple.py

@@ -760,11 +760,13 @@ async def slow_function_2(delay: float = 0.1) -> dict:
  start_time_diff < 0.01
  ), f'Functions started too far apart: {start_time_diff}s'
 
- # Total execution time should be closer to 0.1s (parallel) than 0.2s (sequential)
- # Allow some overhead for task creation and synchronization
- assert (
- total_time < 0.15
- ), f'Execution took too long: {total_time}s, expected < 0.15s'
+ # Total execution time should be less than the sum of all parallel function delays (0.2s)
+ # This proves parallel execution rather than sequential execution
+ sequential_time = 0.2 # 0.1s + 0.1s if functions ran sequentially
+ assert total_time < sequential_time, (
+ f'Execution took too long: {total_time}s, expected < {sequential_time}s'
+ ' (sequential time)'
+ )
 
  # Verify the results are correct
  assert testing_utils.simplify_events(events) == [