Add unit tests for backend acl load

Signed-off-by: Neetha John <nejo@microsoft.com>

tests/config_test.py

@@ -321,6 +321,39 @@ def test_load_minigraph_with_port_config(self, get_cmd_module, setup_single_broa
             port_config = [{"PORT": {"Ethernet0": {"admin_status": "up"}}}]
             self.check_port_config(db, config, port_config, "config interface startup Ethernet0")
 
+    def test_load_backend_acl(self, get_cmd_module, setup_single_broadcom_asic):
+        self.check_backend_acl(get_cmd_module, storage_device=True, device_type='BackEndToRRouter', condition=True)
+
+    def test_load_backend_acl_not_storage(self, get_cmd_module, setup_single_broadcom_asic):
+        self.check_backend_acl(get_cmd_module, storage_device=False, device_type='BackEndToRRouter', condition=False)
+
+    def test_load_backend_acl_storage_leaf(self, get_cmd_module, setup_single_broadcom_asic):
+        self.check_backend_acl(get_cmd_module, storage_device=True, device_type='BackEndLeafRouter', condition=False)
+
+    def check_backend_acl(self, get_cmd_module, storage_device=True, device_type='BackEndToRRouter', condition=True):
+        with mock.patch('config.main._is_storage_device', mock.MagicMock(return_value=storage_device)):
+            def is_file_side_effect(filename):
+                return True if 'backend_acl' in filename else False
+            with mock.patch('os.path.isfile', mock.MagicMock(side_effect=is_file_side_effect)):
+                with mock.patch('config.main._get_device_type', mock.MagicMock(return_value=device_type)):
+                    with mock.patch(
+                        "utilities_common.cli.run_command",
+                        mock.MagicMock(side_effect=mock_run_command_side_effect)) as mock_run_command:
+                        (config, show) = get_cmd_module
+                        runner = CliRunner()
+                        result = runner.invoke(config.config.commands["load_minigraph"], ["-y"])
+                        print(result.exit_code)
+                        expected_output = ['Running command: acl-loader update incremental /etc/sonic/backend_acl.json',
+                                           'Running command: /usr/local/bin/sonic-cfggen -d -t /usr/share/sonic/templates/backend_acl.j2,/etc/sonic/backend_acl.json'
+                                          ]
+                        print(result.output)
+                        assert result.exit_code == 0
+                        output = result.output.split('\n')
+                        if condition:
+                            assert set(expected_output).issubset(set(output))
+                        else:
+                            assert not(set(expected_output).issubset(set(output)))
+
     def check_port_config(self, db, config, port_config, expected_output):
         def read_json_file_side_effect(filename):
             return port_config