Add hacking rule to enfore no config in tempest.lib

This commit adds a hacking rule to enforce that we never add a config
dependency on tempest/lib. Right now we're completely dependent on
reviewers catching this, it is a strong rule so we should ensure we
can't ever land a change that does this.

Change-Id: I1ab1ba52573c6706a50abcd021759c93dd19aa44

HACKING.rst

@@ -21,6 +21,7 @@ Tempest Specific Commandments
 - [T111] Check that service client names of DELETE should be consistent
 - [T112] Check that tempest.lib should not import local tempest code
 - [T113] Check that tests use data_utils.rand_uuid() instead of uuid.uuid4()
+- [T114] Check that tempest.lib does not use tempest config
 - [N322] Method's default argument shouldn't be mutable
 
 Test Data/Configuration

tempest/hacking/checks.py

@@ -257,6 +257,23 @@ def use_rand_uuid_instead_of_uuid4(logical_line, filename):
     yield (0, msg)
 
 
+def dont_use_config_in_tempest_lib(logical_line, filename):
+    """Check that tempest.lib doesn't use tempest config
+
+    T114
+    """
+
+    if 'tempest/lib/' not in filename:
+        return
+
+    if ('tempest.config' in logical_line
+        or 'from tempest import config' in logical_line
+        or 'oslo_config' in logical_line):
+        msg = ('T114: tempest.lib can not have any dependency on tempest '
+               'config.')
+        yield(0, msg)
+
+
 def factory(register):
     register(import_no_clients_in_api_and_scenario_tests)
     register(scenario_tests_need_service_tags)
@@ -269,4 +286,5 @@ def factory(register):
     register(get_resources_on_service_clients)
     register(delete_resources_on_service_clients)
     register(dont_import_local_tempest_into_lib)
+    register(dont_use_config_in_tempest_lib)
     register(use_rand_uuid_instead_of_uuid4)

tempest/tests/test_hacking.py

@@ -167,3 +167,16 @@ class HackingTestCase(base.TestCase):
         self.assertEqual(1, len(list(checks.dont_import_local_tempest_into_lib(
             "import tempest.exception",
             './tempest/lib/common/compute.py'))))
+
+    def test_dont_use_config_in_tempest_lib(self):
+        self.assertFalse(list(checks.dont_use_config_in_tempest_lib(
+            'from tempest import config', './tempest/common/compute.py')))
+        self.assertFalse(list(checks.dont_use_config_in_tempest_lib(
+            'from oslo_concurrency import lockutils',
+            './tempest/lib/auth.py')))
+        self.assertTrue(list(checks.dont_use_config_in_tempest_lib(
+            'from tempest import config', './tempest/lib/auth.py')))
+        self.assertTrue(list(checks.dont_use_config_in_tempest_lib(
+            'from oslo_config import cfg', './tempest/lib/decorators.py')))
+        self.assertTrue(list(checks.dont_use_config_in_tempest_lib(
+            'import tempest.config', './tempest/lib/common/rest_client.py')))