Add test coverage for missing general_calculations in MolecularData.load

src/openfermion/chem/molecular_data.py

@@ -910,10 +910,7 @@ def load(self):
                         for key, value in zip(keys[...], values[...])
                     }
             else:
-                # TODO: test the no cover
-                # no coverage here because pathway is check on
-                # bad user generated file
-                self.general_calculations = None  # pragma: nocover
+                self.general_calculations = {}
 
     def get_from_file(self, property_name):
         """Helper routine to re-open HDF5 file and pull out single property.

src/openfermion/chem/molecular_data_test.py

@@ -13,6 +13,7 @@
 
 import os
 import unittest
+import h5py
 import numpy.random
 import scipy.linalg
 import numpy as np
@@ -347,3 +348,23 @@ def test_missing_calcs_for_integrals(self):
             molecule.get_k()
         with self.assertRaises(MissingCalculationError):
             molecule.get_antisym()
+
+    def test_load_no_general_calculations(self):
+        # Make fake molecule.
+        filename = os.path.join(DATA_DIRECTORY, 'dummy_molecule_no_gen_calc')
+        geometry = [('H', (0.0, 0.0, 0.0)), ('H', (0.0, 0.0, 0.7414))]
+        basis = '6-31g*'
+        multiplicity = 1
+        molecule = MolecularData(geometry, basis, multiplicity, filename=filename)
+        try:
+            molecule.save()
+
+            # Manually remove the general_calculations_keys dataset.
+            with h5py.File(filename + '.hdf5', 'r+') as f:
+                del f['general_calculations_keys']
+
+            # Load the molecule and check that general_calculations is empty.
+            new_molecule = MolecularData(filename=filename)
+            self.assertEqual(new_molecule.general_calculations, {})
+        finally:
+            os.remove(filename + '.hdf5')