Add test for bad MDTraj atom index input

Author: dwhswenson

paths_cli/tests/parsing/test_tools.py

@@ -0,0 +1,14 @@
+import pytest
+import numpy.testing as npt
+
+from paths_cli.parsing.tools import *
+
+@pytest.mark.parametrize('expr,expected', [
+    ('1+1', 2)
+])
+def test_custom_eval(expr, expected):
+    npt.assert_allclose(custom_eval(expr), expected)
+
+def test_mdtraj_parse_atomlist_bad_input():
+    with pytest.raises(TypeError, match="not integers"):
+        mdtraj_parse_atomlist("['a', 'b']", n_atoms=2)