Always set xlim, ylim, zlim in plot functions

[linpy.git] / pypol / tests / test_domains.py

diff --git a/pypol/tests/test_domains.py b/pypol/tests/test_domains.py
index e4f996c..755547e 100644 (file)
--- a/pypol/tests/test_domains.py
+++ b/pypol/tests/test_domains.py
@@ -104,7 +104,8 @@ class TestDomain(unittest.TestCase):
 
     def test_sample(self):
         self.assertEqual(self.square6.sample(), {Symbol('x'): 1, Symbol('y'): 3})
-        self.assertEqual(self.empty.sample(), None)
+        with self.assertRaises(ValueError):
+            self.empty.sample()
         self.assertEqual(self.universe.sample(), {})
 
     def test_intersection(self):