Add pylint with indent check

This is an initial creation of pylint with a basic indent checker.
Small issues corrected.  Job added to gate with
Ib554a284e92583cc1d6a5c2219b3922852ca4c73

Change-Id: I7e24d8348db3aef79e1395d12692199a1f80161a
Co-Authored-By: Andreas Florath <andreas@florath.net>

diskimage_builder/tests/test_elementdeps.py

@@ -27,15 +27,17 @@ data_dir = os.path.abspath(
 
 
 def _populate_element(element_dir, element_name, element_deps=[], provides=[]):
-        logger.debug("Populate %s <%s>" % (element_name, element_dir))
-        element_home = os.path.join(element_dir, element_name)
-        os.mkdir(element_home)
-        deps_path = os.path.join(element_home, 'element-deps')
-        with open(deps_path, 'w') as deps_file:
-            deps_file.write("\n".join(element_deps))
+    logger.debug("Populate %s <%s>" % (element_name, element_dir))
+    element_home = os.path.join(element_dir, element_name)
+    os.mkdir(element_home)
+    deps_path = os.path.join(element_home, 'element-deps')
+
+    with open(deps_path, 'w') as deps_file:
+        deps_file.write("\n".join(element_deps))
         provides_path = os.path.join(element_home, 'element-provides')
-        with open(provides_path, 'w') as provides_file:
-            provides_file.write("\n".join(provides))
+
+    with open(provides_path, 'w') as provides_file:
+        provides_file.write("\n".join(provides))
 
 
 class TestElementDeps(testtools.TestCase):
@@ -94,11 +96,11 @@ class TestElementDeps(testtools.TestCase):
 
     # helper to return an (element, path) tuple from the standard dir
     def _e(self, element):
-            return (element, os.path.join(self.element_dir, element))
+        return (element, os.path.join(self.element_dir, element))
 
     # helper to return an (element, path) tuple from the override dir
     def _eo(self, element):
-            return (element, os.path.join(self.element_override_dir, element))
+        return (element, os.path.join(self.element_override_dir, element))
 
     def test_non_transitive_deps(self):
         result = element_dependencies.get_elements(['requires-foo'],

pylint.cfg

@@ -0,0 +1,7 @@
+[MASTER]
+persistent=no
+
+[MESSAGES CONTROL]
+
+disable=all
+enable=bad-indentation

test-requirements.txt

@@ -2,6 +2,7 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 hacking<0.11,>=0.10.0
+pylint==1.4.5 # GPLv2
 
 oslotest>=1.10.0 # Apache-2.0
 testrepository>=0.0.18 # Apache-2.0/BSD

tox.ini

@@ -16,6 +16,11 @@ commands =
   flake8 {posargs}
   dib-lint
 
+[testenv:pylint]
+setenv = VIRTUAL_ENV={envdir}
+deps = pylint
+commands = pylint --rcfile pylint.cfg diskimage_builder
+
 [testenv:venv]
 commands = {posargs}