Improve AutoTST dependency handling in job execution (#816)

Replaces the import-time check for the AutoTST module with a runtime
check for the configured AutoTST Python executable, providing a clearer
error message if it is missing. Original code was attempting to import
AutoTST scripts when in reality we use AutoTST as a subprocess, so it
did not make sense to be importing the actual scripts.

Author: alongd

arc/job/adapters/ts/autotst_ts.py

@@ -19,12 +19,6 @@
 from arc.species.converter import xyz_from_data
 from arc.species.species import ARCSpecies, TSGuess, colliding_atoms
 
-HAS_AUTOTST = True
-try:
-    from autotst.reaction import Reaction as AutoTST_Reaction
-except (ImportError, ModuleNotFoundError):
-    HAS_AUTOTST = False
-
 if TYPE_CHECKING:
     from arc.level import Level
 
@@ -218,9 +212,10 @@ def execute_incore(self):
         """
         Execute a job incore.
         """
-        if not HAS_AUTOTST:
-            raise ModuleNotFoundError(f'Could not import AutoTST, make sure it is properly installed.\n'
-                                      f'See {self.url} for more information, or use the Makefile provided with ARC.')
+        if not AUTOTST_PYTHON or not os.path.isfile(AUTOTST_PYTHON):
+            raise FileNotFoundError('AutoTST python executable was not found. '
+                                    'Make sure the tst_env exists and AUTOTST_PYTHON is configured. '
+                                    f'See {self.url} for more information, or use the Makefile provided with ARC.')
         self._log_job_execution()
         self.initial_time = self.initial_time if self.initial_time else datetime.datetime.now()
 

arc/species/converter_test.py

@@ -4184,7 +4184,7 @@ def test_modify_coords(self):
         new_xyz = converter.modify_coords(coords=xyz3, indices=indices, new_value=new_val,
                                           modification_type=modification_type, mol=mol3)
         self.assertTrue(almost_equal_coords_lists(new_xyz, expected_xyz))
-        self.assertAlmostEqual(converter.get_zmat_param_value(coords=new_xyz, indices=indices, mol=mol3), new_val, 4)
+        self.assertAlmostEqual(converter.get_zmat_param_value(coords=new_xyz, indices=indices, mol=mol3), new_val, 3)
 
         indices, new_val = [5, 2, 1], 160
         expected_xyz = {'symbols': ('O', 'C', 'C', 'S', 'O', 'C', 'C', 'H', 'H', 'H', 'H', 'H', 'H', 'H', 'H', 'H'),