1 files changed, 12 insertions, 1 deletions
diff --git a/Lib/test/test_trace.py b/Lib/test/test_trace.py
index 461d1d8e6a..fa0d48ca6d 100644
--- a/Lib/test/test_trace.py
+++ b/Lib/test/test_trace.py
@@ -102,6 +102,7 @@ class TracedClass(object):
 class TestLineCounts(unittest.TestCase):
     """White-box testing of line-counting, via runfunc"""
     def setUp(self):
+        self.addCleanup(sys.settrace, sys.gettrace())
         self.tracer = Trace(count=1, trace=0, countfuncs=0, countcallers=0)
         self.my_py_filename = fix_ext_py(__file__)
 
@@ -192,6 +193,7 @@ class TestRunExecCounts(unittest.TestCase):
     """A simple sanity test of line-counting, via runctx (exec)"""
     def setUp(self):
         self.my_py_filename = fix_ext_py(__file__)
+        self.addCleanup(sys.settrace, sys.gettrace())
 
     def test_exec_counts(self):
         self.tracer = Trace(count=1, trace=0, countfuncs=0, countcallers=0)
@@ -218,6 +220,7 @@ class TestRunExecCounts(unittest.TestCase):
 class TestFuncs(unittest.TestCase):
     """White-box testing of funcs tracing"""
     def setUp(self):
+        self.addCleanup(sys.settrace, sys.gettrace())
         self.tracer = Trace(count=0, trace=0, countfuncs=1)
         self.filemod = my_file_and_modname()
 
@@ -242,6 +245,8 @@ class TestFuncs(unittest.TestCase):
         }
         self.assertEqual(self.tracer.results().calledfuncs, expected)
 
+    @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
+                     'pre-existing trace function throws off measurements')
     def test_inst_method_calling(self):
         obj = TracedClass(20)
         self.tracer.runfunc(obj.inst_method_calling, 1)
@@ -257,9 +262,12 @@ class TestFuncs(unittest.TestCase):
 class TestCallers(unittest.TestCase):
     """White-box testing of callers tracing"""
     def setUp(self):
+        self.addCleanup(sys.settrace, sys.gettrace())
         self.tracer = Trace(count=0, trace=0, countcallers=1)
         self.filemod = my_file_and_modname()
 
+    @unittest.skipIf(hasattr(sys, 'gettrace') and sys.gettrace(),
+                     'pre-existing trace function throws off measurements')
     def test_loop_caller_importing(self):
         self.tracer.runfunc(traced_func_importing_caller, 1)
 
@@ -280,6 +288,9 @@ class TestCallers(unittest.TestCase):
 
 # Created separately for issue #3821
 class TestCoverage(unittest.TestCase):
+    def setUp(self):
+        self.addCleanup(sys.settrace, sys.gettrace())
+
     def tearDown(self):
         rmtree(TESTFN)
         unlink(TESTFN)
@@ -311,7 +322,7 @@ class TestCoverage(unittest.TestCase):
             self._coverage(tracer)
         if os.path.exists(TESTFN):
             files = os.listdir(TESTFN)
-            self.assertEqual(files, [])
+            self.assertEqual(files, ['_importlib.cover'])  # Ignore __import__
 
     def test_issue9936(self):
         tracer = trace.Trace(trace=0, count=1)