Use nextval function instead of query 'SELECT nextval'

Fixes: https://pagure.io/koji/issue/3483

tests/test_hub/test_add_channel.py

@@ -24,7 +24,7 @@ class TestAddChannel(unittest.TestCase):
         self.insert_execute = mock.MagicMock()
         self.verify_name_internal = mock.patch('kojihub.verify_name_internal').start()
         self.get_channel = mock.patch('kojihub.get_channel').start()
-        self._singleValue = mock.patch('kojihub._singleValue').start()
+        self.nextval = mock.patch('kojihub.nextval').start()
 
     def tearDown(self):
         mock.patch.stopall()
@@ -41,12 +41,12 @@ class TestAddChannel(unittest.TestCase):
         with self.assertRaises(koji.GenericError):
             self.exports.addChannel(self.channel_name)
         self.get_channel.assert_called_once_with(self.channel_name, strict=False)
-        self._singleValue.assert_not_called()
+        self.nextval.assert_not_called()
         self.assertEqual(len(self.inserts), 0)
 
     def test_add_channel_valid(self):
         self.get_channel.return_value = {}
-        self._singleValue.side_effect = [12]
+        self.nextval.side_effect = [12]
         self.verify_name_internal.return_value = None
 
         r = self.exports.addChannel(self.channel_name, description=self.description)
@@ -60,10 +60,8 @@ class TestAddChannel(unittest.TestCase):
 
         self.context.session.assertPerm.assert_called_once_with('admin')
         self.get_channel.assert_called_once_with(self.channel_name, strict=False)
-        self.assertEqual(self._singleValue.call_count, 1)
-        self._singleValue.assert_has_calls([
-            mock.call("SELECT nextval('channels_id_seq')", strict=True)
-        ])
+        self.assertEqual(self.nextval.call_count, 1)
+        self.nextval.assert_called_once_with('channels_id_seq')
 
     def test_add_channel_wrong_name(self):
         # name is longer as expected

tests/test_hub/test_add_host.py

@@ -41,6 +41,7 @@ class TestAddHost(unittest.TestCase):
         self._dml = mock.patch('kojihub._dml').start()
         self.get_host = mock.patch('kojihub.get_host').start()
         self._singleValue = mock.patch('kojihub._singleValue').start()
+        self.nextval = mock.patch('kojihub.nextval').start()
         self.get_user = mock.patch('kojihub.get_user').start()
 
     def tearDown(self):
@@ -58,7 +59,8 @@ class TestAddHost(unittest.TestCase):
     def test_add_host_valid(self):
         self.verify_host_name.return_value = None
         self.get_host.return_value = {}
-        self._singleValue.side_effect = [333, 12]
+        self._singleValue.return_value = 333
+        self.nextval.return_value = 12
         self.context.session.createUser.return_value = 456
         self.get_user.return_value = None
 
@@ -69,11 +71,8 @@ class TestAddHost(unittest.TestCase):
         kojihub.get_host.assert_called_once_with('hostname')
         self.context.session.createUser.assert_called_once_with(
             'hostname', usertype=koji.USERTYPES['HOST'], krb_principal='-hostname-')
-        self.assertEqual(self._singleValue.call_count, 2)
-        self._singleValue.assert_has_calls([
-            mock.call("SELECT id FROM channels WHERE name = 'default'"),
-            mock.call("SELECT nextval('host_id_seq')", strict=True)
-        ])
+        self._singleValue.assert_called_once_with("SELECT id FROM channels WHERE name = 'default'")
+        self.nextval.assert_called_once_with('host_id_seq')
         self.assertEqual(self._dml.call_count, 1)
         self._dml.assert_called_once_with("INSERT INTO host (id, user_id, name) "
                                           "VALUES (%(hostID)i, %(userID)i, %(hostname)s)",

tests/test_hub/test_new_build.py

@@ -36,7 +36,7 @@ class TestNewBuild(unittest.TestCase):
 
     def test_valid(self):
         self.get_build.return_value = None
-        self._singleValue.return_value = 65  # free build id
+        self.nextval.return_value = 65  # free build id
         self.new_package.return_value = 54
         self.get_user.return_value = {'id': 123}
         data = {