EXPECT_POOR_TIMER_RESOLUTION should cover this case too.

src/greentest/greentest/sysinfo.py

@@ -107,7 +107,10 @@ if RUNNING_ON_APPVEYOR:
     # 'develop' mode (i.e., we install)
     NON_APPLICABLE_SUFFIXES.append('corecext')
 
-EXPECT_POOR_TIMER_RESOLUTION = PYPY3 or RUNNING_ON_APPVEYOR or (LIBUV and PYPY)
+EXPECT_POOR_TIMER_RESOLUTION = (PYPY3
+                                or RUNNING_ON_APPVEYOR
+                                or (LIBUV and PYPY)
+                                or (CFFI_BACKEND and RUN_COVERAGE))
 
 
 CONN_ABORTED_ERRORS = []

src/greentest/greentest/testcase.py

@@ -225,7 +225,7 @@ class TestCase(TestCaseMetaClass("NewBase", (BaseTestCase,), {})):
             self.assertIsInstance(econtext, where_type)
         return error
 
-    if sysinfo.RUNNING_ON_APPVEYOR:
+    if sysinfo.EXPECT_POOR_TIMER_RESOLUTION:
         # pylint:disable=unused-argument
         # appveyor timeouts are unreliable; seems to be very slow wakeups
         def assertTimeoutAlmostEqual(self, *args, **kwargs):
@@ -237,9 +237,9 @@ class TestCase(TestCaseMetaClass("NewBase", (BaseTestCase,), {})):
         def assertTimeoutAlmostEqual(self, *args, **kwargs):
             self.assertAlmostEqual(*args, **kwargs)
 
-        def assertTimeWithinRange(self, delay, min_time, max_time):
-            self.assertLessEqual(delay, max_time)
-            self.assertGreaterEqual(delay, min_time)
+        def assertTimeWithinRange(self, time_taken, min_time, max_time):
+            self.assertLessEqual(time_taken, max_time)
+            self.assertGreaterEqual(time_taken, min_time)
 
 
     def assertMonkeyPatchedFuncSignatures(self, mod_name, func_names=(), exclude=()):

src/greentest/greentest/timing.py

@@ -46,8 +46,9 @@ class _DelayWaitMixin(object):
                             delay_max_adj=None):
         delay_min_adj = self._default_delay_min_adj if not delay_min_adj else delay_min_adj
         delay_max_adj = self._default_delay_max_adj if not delay_max_adj else delay_max_adj
-        self.assertGreaterEqual(delay, timeout - delay_min_adj)
-        self.assertLess(delay, timeout + delay_max_adj)
+        self.assertTimeWithinRange(delay,
+                                   timeout - delay_min_adj,
+                                   timeout + delay_max_adj)
 
     def _wait_and_check(self, timeout=None):
         if timeout is None: