Improve test resiliency

Avoids occasional test executions failures
caused by leftover files on dev machine or
by preexisting configuration files.

Change-Id: Ia0ba29e2dda58c37410a6926cae3039e4ba3473e

.gitignore

@@ -16,7 +16,8 @@ etc/jenkins_jobs.ini
 dist/*
 doc/build/*
 jenkins_jobs/versioninfo
-.coverage
+.coverage*
 cover/
 jenkins-job-builder
 testr_subunit_log
+__pycache__

jenkins_jobs/config.py

@@ -199,10 +199,10 @@ class JJBConfig(object):
         # check the ignore_cache setting
         ignore_cache = False
         if config.has_option(self._section, 'ignore_cache'):
-            logging.warning("ignore_cache option should be moved to the "
-                            "[job_builder] section in the config file, the "
-                            "one specified in the [jenkins] section will be "
-                            "ignored in the future")
+            logger.warning("ignore_cache option should be moved to the "
+                           "[job_builder] section in the config file, the "
+                           "one specified in the [jenkins] section will be "
+                           "ignored in the future")
             ignore_cache = config.getboolean(self._section, 'ignore_cache')
         elif config.has_option('job_builder', 'ignore_cache'):
             ignore_cache = config.getboolean('job_builder', 'ignore_cache')

tests/base.py

@@ -100,8 +100,11 @@ def get_scenarios(fixtures_path, in_ext='yaml', out_ext='xml',
         conf_candidate = re.sub(r'\.yaml$|\.json$', '.conf', input_filename)
         conf_filename = files.get(os.path.basename(conf_candidate), None)
 
-        if conf_filename is not None:
+        if conf_filename:
             conf_filename = conf_filename[0]
+        else:
+            # for testing purposes we want to avoid using user config files
+            conf_filename = os.devnull
 
         scenarios.append((input_filename, {
             'in_filename': input_filename,

tox.ini

@@ -5,15 +5,23 @@ skip_missing_interpreters = true
 
 [testenv]
 # Note(Vek): JJB is not compatible with a non-zero PYTHONHASHSEED
-setenv = VIRTUAL_ENV={envdir}
-         SUBUNIT_FORMATTER=tee testr_subunit_log
-         OS_STDOUT_NOCAPTURE=False
-         PYTHONHASHSEED=0
+setenv =
          LANG=en_US.UTF-8
+         PYTHONDONTWRITEBYTECODE=1
+         PYTHONHASHSEED=0
+         SUBUNIT_FORMATTER=tee testr_subunit_log
+         VIRTUAL_ENV={envdir}
 usedevelop = True
 install_command = pip install {opts} {packages}
 deps = -r{toxinidir}/test-requirements.txt
-commands = python setup.py testr --slowest --testr-args='{posargs}'
+# cleanup is needed mostly for dev environmnts and assures that if  dev
+# is switching branch, no lefovers will impact execution.
+# No git commands here because test should run even from a source archive.
+commands =
+    - find . -type f -name "*.pyc" -delete
+    - find . -type d -name "__pycache__" -delete
+    python setup.py testr --slowest --testr-args='{posargs}'
+whitelist_externals = find
 
 [testenv:cover]
 commands =