Integration Testing: tox env, pyxld 2.2.3, and revamp framework

Massive update to clean up and greatly enhance the integration testing
framework developed by Wesley Wiedenmeier.

 - Updated tox environment to run integration test 'citest' to utilize
   pylxd 2.2.3
 - Add support for distro feature flags
   - add framework for feature flags to release config with feature groups
     and overrides allowed in any release conf override level
   - add support for feature flags in platform and config handling
   - during collect, skip testcases that require features not supported by
     the image with a warning message
 - Enable additional distros (i.e. centos, debian)
 - Add 'bddeb' command to build a deb from the current working tree
   cleanly in a container, so deps do not have to be installed on host
 - Adds a command line option '--preserve-data' that ensures that
   collected data will be left after tests run. This also allows the
   directory to store collected data in during the run command to be
   specified using '--data-dir'.
 - Updated Read the Docs testing page and doc strings for pep 257
   compliance

1 files changed, 3 insertions, 4 deletions

diff --git a/tests/cloud_tests/images/__init__.py b/tests/cloud_tests/images/__init__.py
index b27d6931..106c59f3 100644
--- a/tests/cloud_tests/images/__init__.py
+++ b/tests/cloud_tests/images/__init__.py
@@ -1,11 +1,10 @@
 # This file is part of cloud-init. See LICENSE file for license information.
 
+"""Main init."""
+
 
 def get_image(platform, config):
-    """
-    get image from platform object using os_name, looking up img_conf in main
-    config file
-    """
+    """Get image from platform object using os_name."""
     return platform.get_image(config)
 
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