revert(test): take back RemoveUnusedSolutionsTC from 615f5fbf8718

cubicweb/server/test/unittest_rql2sql.py

@@ -2016,5 +2016,29 @@ WHERE _Y.cw_creation_date>(DATETIME(_X.cw_creation_date, "+10 days"))'''),
                 self._check(rql, sql)
 
 
+class RemoveUnsusedSolutionsTC(unittest.TestCase):
+    def test_invariant_not_varying(self):
+        rqlst = mock_object(defined_vars={})
+        rqlst.defined_vars['A'] = mock_object(scope=rqlst, stinfo={}, _q_invariant=True)
+        rqlst.defined_vars['B'] = mock_object(scope=rqlst, stinfo={}, _q_invariant=False)
+        self.assertEqual(
+            rql2sql.remove_unused_solutions(rqlst, [{'A': 'RugbyGroup', 'B': 'RugbyTeam'},
+                                                    {'A': 'FootGroup', 'B': 'FootTeam'}], None),
+            ([{'A': 'RugbyGroup', 'B': 'RugbyTeam'},
+              {'A': 'FootGroup', 'B': 'FootTeam'}],
+             {}, set('B'))
+        )
+
+    def test_invariant_varying(self):
+        rqlst = mock_object(defined_vars={})
+        rqlst.defined_vars['A'] = mock_object(scope=rqlst, stinfo={}, _q_invariant=True)
+        rqlst.defined_vars['B'] = mock_object(scope=rqlst, stinfo={}, _q_invariant=False)
+        self.assertEqual(
+            rql2sql.remove_unused_solutions(rqlst, [{'A': 'RugbyGroup', 'B': 'RugbyTeam'},
+                                                    {'A': 'FootGroup', 'B': 'RugbyTeam'}], None),
+            ([{'A': 'RugbyGroup', 'B': 'RugbyTeam'}], {}, set())
+        )
+
+
 if __name__ == '__main__':
     unittest.main()