Change SG test syntax as per @pavoljuhas review, add to changelog

Signed-off-by: Håkon Wiik Ånes <[email protected]>

Author: hakonanes

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Added
 
+- A string representation of `SpaceGroup` with key information.
+
 ### Changed
 
 ### Deprecated

src/diffpy/structure/tests/testspacegroups.py

@@ -111,9 +111,8 @@ def test_spacegroup_representation(self):
                                "SpaceGroup #%i (%s, %s). Symmetry matrices: %i, "
                                "point sym. matr.: %i"
                            ) % ((key,) + value)
-
             self.assertEqual(sg.__repr__(), expected_str)
-
+        return
 
 # End of class TestRoutines