Minor improvements in testing of new expressions

diff --git a/pypol/tests/test_linexprs.py b/pypol/tests/test_linexprs.py
index 5beaa17..c55c842 100644 (file)
--- a/pypol/tests/test_linexprs.py
+++ b/pypol/tests/test_linexprs.py
@@ -19,8 +19,8 @@ class TestExpression(unittest.TestCase):
         self.expr = self.x - 2*self.y + 3
 
     def test_new(self):
-        self.assertIsInstance(self.x, Symbol)
-        self.assertIsInstance(self.pi, Rational)
+        self.assertIsInstance(Expression(coefficients={self.x: 1}), Symbol)
+        self.assertIsInstance(Expression(constant=self.pi), Rational)
         self.assertNotIsInstance(self.x + self.pi, Symbol)
         self.assertNotIsInstance(self.x + self.pi, Rational)
         xx = Expression({self.x: 2})