#19: Plural error and test

movement/tangling.py

@@ -60,7 +60,8 @@ def check(self):
         sj = self.scaled_jacobian.dat.data_with_halos
         num_tangled = len(sj[sj < 0])
         if num_tangled > 0:
-            msg = f"Mesh has {num_tangled} tangled elements."
+            plural = "s" if num_tangled > 1 else ""
+            msg = f"Mesh has {num_tangled} tangled element{plural}."
             if self.raise_error:
                 raise ValueError(msg)
             warnings.warn(msg)

test/test_tangling.py

@@ -8,16 +8,25 @@ class TestTangling(unittest.TestCase):
     Unit tests for mesh tangling checking.
     """
 
-    def test_tangling_checker_error(self):
+    def test_tangling_checker_error1(self):
         mesh = UnitSquareMesh(3, 3)
         checker = MeshTanglingChecker(mesh, raise_error=True)
         mesh.coordinates.dat.data[3] += 0.2
         with self.assertRaises(ValueError) as cm:
             checker.check()
-        msg = "Mesh has 1 tangled elements."
+        msg = "Mesh has 1 tangled element."
         self.assertEqual(str(cm.exception), msg)
 
-    def test_tangling_checker_warning(self):
+    def test_tangling_checker_error2(self):
+        mesh = UnitSquareMesh(3, 3)
+        checker = MeshTanglingChecker(mesh, raise_error=True)
+        mesh.coordinates.dat.data[3] += 0.5
+        with self.assertRaises(ValueError) as cm:
+            checker.check()
+        msg = "Mesh has 3 tangled elements."
+        self.assertEqual(str(cm.exception), msg)
+
+    def test_tangling_checker_warning1(self):
         mesh = UnitSquareMesh(3, 3)
         checker = MeshTanglingChecker(mesh, raise_error=False)
         self.assertEqual(checker.check(), 0)