smoketest: add shim for every test to re-use common tasts

Currently every smoketest does the setup and destruction of the configsession
on its own durin setUp(). This creates a lot of overhead and one configsession
should be re-used during execution of every smoketest script.

In addiion a test that failed will leaf the system in an unconsistent state.
For this reason before the test is executed we will save the running config
to /tmp and the will re-load the config after the test has passed, always
ensuring a clean environment for the next test.

1 files changed, 90 insertions, 0 deletions

diff --git a/smoketest/scripts/cli/base_vyostest_shim.py b/smoketest/scripts/cli/base_vyostest_shim.py
new file mode 100644
index 000000000..18e4e567e
--- /dev/null
+++ b/smoketest/scripts/cli/base_vyostest_shim.py
@@ -0,0 +1,90 @@
+# Copyright (C) 2021 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import unittest
+
+from time import sleep
+
+from vyos.configsession import ConfigSession
+from vyos.configsession import ConfigSessionError
+from vyos import ConfigError
+from vyos.util import cmd
+
+save_config = '/tmp/vyos-smoketest-save'
+
+# This class acts as shim between individual Smoketests developed for VyOS and
+# the Python UnitTest framework. Before every test is loaded, we dump the current
+# system configuration and reload it after the test - despite the test results.
+#
+# Using this approach we can not render a live system useless while running any
+# kind of smoketest. In addition it adds debug capabilities like printing the
+# command used to execute the test.
+class VyOSUnitTestSHIM:
+    class TestCase(unittest.TestCase):
+        # if enabled in derived class, print out each and every set/del command
+        # on the CLI. This is usefull to grap all the commands required to
+        # trigger the certain failure condition.
+        # Use "self.debug = True" in derived classes setUp() method
+        debug = False
+
+        @classmethod
+        def setUpClass(cls):
+            cls._session = ConfigSession(os.getpid())
+            cls._session.save_config(save_config)
+            pass
+
+        @classmethod
+        def tearDownClass(cls):
+            # discard any pending changes which might caused a messed up config
+            cls._session.discard()
+            # ... and restore the initial state
+            cls._session.migrate_and_load_config(save_config)
+
+            try:
+                cls._session.commit()
+            except (ConfigError, ConfigSessionError):
+                cls._session.discard()
+                cls.fail(cls)
+
+        def cli_set(self, config):
+            if self.debug:
+                print('set ' + ' '.join(config))
+            self._session.set(config)
+
+        def cli_delete(self, config):
+            if self.debug:
+                print('del ' + ' '.join(config))
+            self._session.delete(config)
+
+        def cli_commit(self):
+            self._session.commit()
+
+        def getFRRconfig(self, string, end='$'):
+            """ Retrieve current "running configuration" from FRR """
+            command = f'vtysh -c "show run" | sed -n "/^{string}{end}/,/^!/p"'
+
+            count = 0
+            tmp = ''
+            while count < 10 and tmp == '':
+                # Let FRR settle after a config change first before harassing it again
+                sleep(1)
+                tmp = cmd(command)
+                count += 1
+
+            if self.debug or tmp == '':
+                import pprint
+                print(f'\n\ncommand "{command}" returned:\n')
+                pprint.pprint(tmp)
+            return tmp