Issue #10990: Prevent tests from clobbering a set trace function.
Many tests simply didn't care if they unset a pre-existing trace function. This
made test coverage impossible. This patch fixes various tests to put back any
pre-existing trace function. It also introduces test.support.no_tracing as a
decorator which will temporarily unset the trace function for tests which
simply fail otherwise.
Thanks to Kristian Vlaardingerbroek for helping to find the cause of various
trace function unsets.
diff --git a/Lib/test/support.py b/Lib/test/support.py
index ea5b9cb..f037a7a 100644
--- a/Lib/test/support.py
+++ b/Lib/test/support.py
@@ -1108,6 +1108,21 @@
return guards.get(platform.python_implementation().lower(), default)
+def no_tracing(func):
+ """Decorator to temporarily turn off tracing for the duration of a test."""
+ if not hasattr(sys, 'gettrace'):
+ return func
+ else:
+ @functools.wraps(func)
+ def wrapper(*args, **kwargs):
+ original_trace = sys.gettrace()
+ try:
+ sys.settrace(None)
+ return func(*args, **kwargs)
+ finally:
+ sys.settrace(original_trace)
+ return wrapper
+
def _run_suite(suite):
"""Run tests from a unittest.TestSuite-derived class."""