bpo-36454: Fix test_time.test_monotonic() (GH-12929)

Change test_time.test_monotonic() to test only the lower bound of elapsed time
after a sleep command rather than the upper bound. This prevents unnecessary
test failures on slow buildbots. Patch by Victor Stinner.

Lib/test/test_time.py

@@ -470,8 +470,9 @@ class TimeTestCase(unittest.TestCase):
         t2 = time.monotonic()
         dt = t2 - t1
         self.assertGreater(t2, t1)
-        # Issue #20101: On some Windows machines, dt may be slightly low
-        self.assertTrue(0.45 <= dt <= 1.0, dt)
+        # bpo-20101: tolerate a difference of 50 ms because of bad timer
+        # resolution on Windows
+        self.assertTrue(0.450 <= dt)
 
         # monotonic() is a monotonic but non adjustable clock
         info = time.get_clock_info('monotonic')

Misc/NEWS.d/next/Tests/2019-04-23-17-48-11.bpo-36454.0q4lQz.rst

+Change test_time.test_monotonic() to test only the lower bound of elapsed time
+after a sleep command rather than the upper bound. This prevents unnecessary
+test failures on slow buildbots. Patch by Victor Stinner.