Address PR comments

Author: Theofilos Manitaras

docs/tutorial.rst

@@ -824,7 +824,7 @@ The first occurrence will be used as the reference value of the ``perf`` perform
 In our example, the ``perf`` key will be resolved in the ``daint:gpu`` scope giving us the reference value.
 
 Reference values in ReFrame are specified as a three-tuple comprising the reference value and lower and upper thresholds.
-Thresholds are specified as decimal fractions of the reference value. For nonnegative reference values, the lower threshold must lie in the [-1,0], whereas the upper threshold must lie in the [0,inf] interval.
+Thresholds are specified as decimal fractions of the reference value. For nonnegative reference values, the lower threshold must lie in the [-1,0], whereas the upper threshold may be any positive real number or zero.
 In our example, the reference value for this test on ``daint:gpu`` is 50 Gflop/s ±10%. Setting a threshold value to :class:`None` disables the threshold.
 
 Combining It All Together

reframe/utility/sanity.py

@@ -483,28 +483,20 @@ def assert_reference(val, ref, lower_thres=None, upper_thres=None, msg=None):
         lower and upper thresholds do not have appropriate values.
     """
     if lower_thres is not None:
-        if ref >= 0.0:
-            try:
-                evaluate(assert_bounded(lower_thres, -1, 0))
-            except SanityError:
-                raise SanityError('invalid low threshold value: %s' % lower_thres)
-        else:
-            try:
-                evaluate(assert_bounded(lower_thres, None, 0))
-            except SanityError:
-                raise SanityError('invalid low threshold value: %s' % lower_thres)
+        lower_thres_limit = -1 if ref >= 0 else None
+        try:
+            evaluate(assert_bounded(lower_thres, lower_thres_limit, 0))
+        except SanityError:
+            raise SanityError('invalid low threshold value: %s'
+                              % lower_thres) from None
 
     if upper_thres is not None:
-        if ref >= 0.0:
-            try:
-                evaluate(assert_bounded(upper_thres, 0, None))
-            except SanityError:
-                raise SanityError('invalid high threshold value: %s' % upper_thres)
-        else:
-            try:
-                evaluate(assert_bounded(upper_thres, 0, 1))
-            except SanityError:
-                raise SanityError('invalid high threshold value: %s' % upper_thres)
+        upper_thres_limit = None if ref >= 0 else 1
+        try:
+            evaluate(assert_bounded(upper_thres, 0, upper_thres_limit))
+        except SanityError:
+            raise SanityError('invalid high threshold value: %s'
+                              % upper_thres) from None
 
     def calc_bound(thres):
         if thres is None:

unittests/test_sanity_functions.py

@@ -341,9 +341,7 @@ def test_assert_reference(self):
         self.assertTrue(sn.assert_reference(-0.9, -1))
 
         # Check upper threshold values greater than 1
-        self.assertTrue(sn.assert_reference(30.0, 10.0, None, 3.0))
-        self.assertTrue(sn.assert_reference(-50.0, -20.0, -2.0, 0.5))
-        self.assertTrue(sn.assert_reference(30.0, 10.0, None, 3.0))
+        self.assertTrue(sn.assert_reference(20.0, 10.0, None, 3.0))
         self.assertTrue(sn.assert_reference(-50.0, -20.0, -2.0, 0.5))
 
         self.assertRaisesRegex(
@@ -392,8 +390,6 @@ def test_assert_reference(self):
                                'invalid high threshold value: 1\.5',
                                evaluate, sn.assert_reference(-1.5, -1, -0.5, 1.5))
 
-
-
     def _write_tempfile(self):
         ret = None
         with NamedTemporaryFile('wt', delete=False) as fp: