Add water test to check bonds and angles

gmso/tests/test_lammps.py

@@ -1,6 +1,8 @@
+import gmso
 from gmso.core.box import Box
 from gmso.formats.lammpsdata import write_lammpsdata
 from gmso.tests.base_test import BaseTest
+from gmso.tests.utils import get_path
 
 
 class TestLammpsWriter(BaseTest):
@@ -12,3 +14,33 @@ def test_write_lammps_triclinic(self, topology_site):
         top = topology_site()
         top.box = Box(lengths=[1,1,1], angles=[60,90,120])
         write_lammpsdata(top, filename='data.triclinic')
+
+    def test_water_lammps(self, water_system):
+        top = water_system
+
+        ff = gmso.ForceField(get_path('tip3p.xml'))
+
+        for site in top.sites:
+            site.atom_type = ff.atom_types[site.name]
+
+        top.update_sites()
+        top.update_atom_types()
+
+        for bond in top.bonds:
+            bond.bond_type = bond.connection_type = ff.bond_types['opls_111~opls_112']
+
+        top.update_bonds()
+        top.update_bond_types()
+
+        for subtop in top.subtops:
+            angle = gmso.core.angle.Angle(
+                connection_members=[site for site in subtop.sites],
+                name="opls_112~opls_111~opls_112",
+                connection_type=ff.angle_types["opls_112~opls_111~opls_112"]
+            )
+            top.add_connection(angle)
+
+        top.update_angles()
+        top.update_angle_types()
+
+        write_lammpsdata(top, 'data.water')