added test

tests/test_libpdb.py

@@ -1,8 +1,12 @@
 """Test lib PDB."""
+from pathlib import Path
 import pytest
 
+
 from haddock.libs import libpdb
+from haddock.libs.libio import PDBFile
 
+from . import golden_data
 
 chainC = [
     'ATOM      3  CA  ARG C   4      37.080  43.455  -3.421  1.00  0.00      C    C  ',  # noqa: E501
@@ -31,3 +35,28 @@ def test_read_chain_ids(lines, expected):
 def test_read_seg_ids(lines, expected):
     result = libpdb.read_segids(lines)
     assert result == expected
+
+
+@pytest.fixture(name="wrong_rigid_molecules")
+def fixture_wrong_rigidbody_molecules():
+    """fixture for wrong rigidbody input molecules."""
+    receptor = PDBFile(Path(golden_data, "protprot_complex_1.pdb"))
+    ligand = PDBFile(Path(golden_data, "protprot_complex_2.pdb"))
+    return [receptor, ligand]
+
+@pytest.fixture(name="good_rigid_molecules")
+def fixture_good_rigidbody_molecules():
+    """fixture for good rigidbody input molecules."""
+    receptor = PDBFile(Path(golden_data, "e2aP_1F3G_haddock.pdb"))
+    ligand = PDBFile(Path(golden_data, "hpr_ensemble_1_haddock.pdb"))
+    return [receptor, ligand]
+
+def test_check_combination_chains(good_rigid_molecules, wrong_rigid_molecules):
+    """Test check_combination_chains."""
+    exp_chains = ["A", "B"]
+    obs_chains = libpdb.check_combination_chains(good_rigid_molecules)
+    assert obs_chains == exp_chains
+    # when input molecules share chains there should be a ValueError
+    with pytest.raises(ValueError):
+        libpdb.check_combination_chains(wrong_rigid_molecules)
+