Test that you can't use the same name for both a key and a keyword

Author: jensj

ase/test/__init__.py

@@ -166,6 +166,20 @@ def __init__(self, size):
     def get_rank(self, rank):
         return CPU(self, rank)
 
+
+class MustRaise:
+    """Context manager for checking raising of exceptions."""
+    def __init__(self, exception):
+        self.exception = exception
+        
+    def __enter__(self):
+        pass
+        
+    def __exit__(self, exc_type, exc_value, tb):
+        if exc_type is None:
+            raise RuntimeError('Failed to fail: ' + str(self.exception))
+        return issubclass(exc_type, self.exception)
+        
 
 class CPU:
     def __init__(self, world, rank):

ase/test/db2.py

@@ -1,8 +1,9 @@
 from ase import Atoms
-from ase.db import connect
-from ase.structure import molecule
 from ase.calculators.emt import EMT
 from ase.constraints import FixAtoms, FixBondLength
+from ase.db import connect
+from ase.structure import molecule
+from ase.test import MustRaise
 
 
 for name in ['y2.json', 'y2.db']:
@@ -39,9 +40,8 @@
     c.update(id, grr='hmm')
     assert c.get(C=1).id == id
 
-    try:
+    with MustRaise(AssertionError):
         c.update(id, ['grr'])
-    except AssertionError:
-        pass
-    else:
-        2 / 0
+    with MustRaise(AssertionError):
+        c.write(ch4, ['foo'], foo='bar')
+