Switch guessers to catching and raising NoDataErrors

package/MDAnalysis/guesser/default_guesser.py

@@ -109,6 +109,7 @@
 
 import re
 
+from ..exceptions import NoDataError
 from ..lib import distances
 from . import tables
 
@@ -218,15 +219,15 @@ def guess_masses(self, atom_types=None, indices_to_guess=None):
         if atom_types is None:
             try:
                 atom_types = self._universe.atoms.elements
-            except AttributeError:
+            except NoDataError:
                 try:
                     atom_types = self._universe.atoms.types
-                except AttributeError:
+                except NoDataError:
                     try:
                         atom_types = self.guess_types(
                             atom_types=self._universe.atoms.names)
-                    except ValueError:
-                        raise ValueError(
+                    except NoDataError:
+                        raise NoDataError(
                             "there is no reference attributes"
                             " (elements, types, or names)"
                             " in this universe to guess mass from")
@@ -291,8 +292,8 @@ def guess_types(self, atom_types=None, indices_to_guess=None):
         if atom_types is None:
             try:
                 atom_types = self._universe.atoms.names
-            except AttributeError:
-                raise ValueError(
+            except NoDataError:
+                raise NoDataError(
                     "there is no reference attributes in this universe"
                     "to guess types from")
 

testsuite/MDAnalysisTests/guesser/test_default_guesser.py

@@ -26,7 +26,8 @@
 
 from numpy.testing import assert_equal, assert_allclose
 import numpy as np
-from MDAnalysis.core.topologyattrs import Angles, Atomtypes, Atomnames, Masses
+from MDAnalysis.core.topologyattrs import Angles, Atomtypes, Atomnames
+from MDAnalysis.exceptions import NoDataError
 from MDAnalysis.guesser.default_guesser import DefaultGuesser
 from MDAnalysis.core.topology import Topology
 from MDAnalysisTests import make_Universe
@@ -82,7 +83,7 @@ def test_guess_atom_mass(self, default_guesser):
 
     def test_guess_masses_with_no_reference_elements(self):
         u = mda.Universe.empty(3)
-        with pytest.raises(ValueError,
+        with pytest.raises(NoDataError,
                            match=('there is no reference attributes ')):
             u.guess_TopologyAttrs('default', ['masses'])
 
@@ -119,7 +120,7 @@ def test_guess_elements_from_no_data(self):
         top = Topology(5)
         msg = "there is no reference attributes in this universe"
         "to guess types from"
-        with pytest.raises(ValueError, match=(msg)):
+        with pytest.raises(NoDataError, match=(msg)):
             mda.Universe(top, to_guess=['types'])
 
     @pytest.mark.parametrize('name, element', (
@@ -148,7 +149,7 @@ def test_guess_charge(default_guesser):
 def test_guess_bonds_Error():
     u = make_Universe(trajectory=True)
     msg = "This Universe does not contain name information"
-    with pytest.raises(ValueError, match=msg):
+    with pytest.raises(NoDataError, match=msg):
         u.guess_TopologyAttrs(to_guess=['bonds'])