add flake8-checks to travis

.travis.yml

@@ -25,6 +25,8 @@ matrix:
       env: TOXENV=pypy3
     - python: 2.7
       env: TOXENV=docs
+    - python: 3.4
+      env: TOXENV=flake8
   allow_failures:
     - python: 3.5-dev
     - python: nightly

setup.cfg

@@ -9,3 +9,4 @@ universal=1
 [flake8]
 exclude = .git,.tox,.github,.eggs,__pycache__,doc/conf.py,build,dist,capabilities-data,test,src/escpos/constants.py
 max-line-length = 120
+# future-imports = absolute_import, division, print_function, unicode_literals  # we are not there yet

setup.py

@@ -50,6 +50,9 @@ setuptools_scm_template = """\
 # coding: utf-8
 # file generated by setuptools_scm
 # don't change, don't track in version control
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
 from __future__ import unicode_literals
 
 version = '{version}'

src/escpos/cli.py

@@ -33,9 +33,11 @@ def str_to_bool(string):
     """
     return string.lower() in ('y', 'yes', '1', 'true')
 
+
 # A list of functions that work better with a newline to be sent after them.
 REQUIRES_NEWLINE = ('qr', 'barcode', 'text', 'block_text')
 
+
 # Used in demo method
 # Key: The name of escpos function and the argument passed on the CLI. Some
 #   manual translation is done in the case of barcodes_a -> barcode.
@@ -568,5 +570,6 @@ def demo(printer, **kwargs):
             command(**params)
         printer.cut()
 
+
 if __name__ == '__main__':
     main()

src/escpos/codepages.py

@@ -20,4 +20,5 @@ class CodePageManager:
     def get_encoding(self, encoding):
         return self.data[encoding]
 
+
 CodePages = CodePageManager(CAPABILITIES['encodings'])

tox.ini

@@ -22,5 +22,6 @@ commands = sphinx-build -W -b html -d {envtmpdir}/doctrees .  {envtmpdir}/html
 
 [testenv:flake8]
 basepython = python
+# TODO add flake8-future
 deps = flake8
 commands = flake8