raise errors when removing site/conn not in top

gmso/core/topology.py

@@ -665,6 +665,10 @@ def remove_site(self, site):
         gmso.core.topology.Topology.iter_connections_by_site
             The method that shows all connections belonging to a specific site
         """
+        if site not in self._sites:
+            raise ValueError(
+                f"Site {site} is not currently part of this topology."
+            )
         for connection in self.iter_connections_by_site(site):
             self.remove_connection(connection)
         self._sites.remove(site)
@@ -682,6 +686,10 @@ def remove_connection(self, connection):
         The sites that belong to this connection are
         not removed from the topology.
         """
+        if connection not in self.connections:
+            raise ValueError(
+                f"Connection {connection} is not currently part of this topology."
+            )
         if isinstance(connection, gmso.core.bond.Bond):
             self._bonds.remove(connection)
         elif isinstance(connection, gmso.core.angle.Angle):

gmso/tests/test_topology.py

@@ -59,6 +59,12 @@ def test_remove_site(self, ethane):
         assert ethane.n_sites == 2
         assert ethane.n_connections == 1
 
+    def test_remove_site_not_in_top(self, ethane):
+        top = Topology()
+        site = Atom(name="site")
+        with pytest.raises(ValueError):
+            top.remove_site(site)
+
     def test_add_connection(self):
         top = Topology()
         atom1 = Atom(name="atom1")
@@ -83,6 +89,14 @@ def test_remove_connection(self):
         top.remove_connection(connect)
         assert top.n_connections == 0
 
+    def test_remove_connection(self):
+        top = Topology()
+        atom1 = Atom(name="atom1")
+        atom2 = Atom(name="atom2")
+        connect = Bond(connection_members=[atom1, atom2])
+        with pytest.raises(ValueError):
+            top.remove_connection(connect)
+
     def test_add_box(self):
         top = Topology()
         box = Box(2 * u.nm * np.ones(3))