diff --git a/.travis.yml b/.travis.yml
index ecdc35b2..9c257de8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,13 +9,17 @@ before_install:
     # Installing Arpeggio as a dependency
     - cd ..
     - pip install Jinja2
+    - pip install coverage
+    - pip install flake8
     - git clone --depth=1 --branch=master git://github.com/igordejanovic/Arpeggio.git
     - cd Arpeggio && python setup.py install
     - cd ../textX
 install:
     - python setup.py install
 script:
-    - py.test tests/functional
+    - coverage run --source textx -m py.test tests/functional
+    - coverage report --fail-under 80
+    - flake8 textx tests --exclude tests/perf,textx/six.py,textx/lang.py
 
 matrix:
   include:
diff --git a/docs/about/contributing.md b/docs/about/contributing.md
index 2a778d4a..c9b44929 100644
--- a/docs/about/contributing.md
+++ b/docs/about/contributing.md
@@ -88,7 +88,7 @@ Ready to contribute? Here's how to set up `textX` for local development.
     
     To verify that everything is setup properly run tests:
     
-        $ flake8 tests/functional/
+        $ flake8 textx tests --exclude tests/perf,textx/six.py,textx/lang.py
         $ py.test tests/functional/
 
 4. Create a branch for local development::
@@ -97,11 +97,18 @@ Ready to contribute? Here's how to set up `textX` for local development.
 
    Now you can make your changes locally.
 
-5. When you're done making changes, check that your changes pass flake8 and the
-   tests:
+5. When you're done making changes, check that your changes pass flake8, the
+   tests, and have a look at the coverage:
 
-        $ flake8 textX tests
+        $ flake8 textx tests/functional
         $ py.test tests/functional/
+        $ coverage run --source textx -m py.test tests/functional
+        $ coverage report
+
+   In case you have doubts, have also a look at the html rendered version of
+   the coverage results:
+
+        $ coverage html
 
 6. Commit your changes and push your branch to GitHub:
 
diff --git a/examples/StateMachine/smdot.py b/examples/StateMachine/smdot.py
index 1a0cda15..63e61b0a 100644
--- a/examples/StateMachine/smdot.py
+++ b/examples/StateMachine/smdot.py
@@ -1,15 +1,11 @@
 """
 Export state machine models to dot.
 """
+from __future__ import unicode_literals
 import codecs
 import sys
 from os.path import dirname, join
 from textx import metamodel_from_file
-if sys.version < '3':
-    text = unicode
-else:
-    text = str
-
 
 HEADER = '''
     digraph xtext {
@@ -64,5 +60,5 @@ def sm_to_dot(model):
         meta = metamodel_from_file(join(this_folder, 'state_machine.tx'))
         model = meta.model_from_file(model_name)
         with codecs.open("{}.dot".format(model_name), 'w',
-                            encoding='utf-8') as f:
+                         encoding='utf-8') as f:
             f.write(sm_to_dot(model))
diff --git a/examples/StateMachine/state_machine.py b/examples/StateMachine/state_machine.py
index 369acb9f..5508ee07 100644
--- a/examples/StateMachine/state_machine.py
+++ b/examples/StateMachine/state_machine.py
@@ -55,14 +55,13 @@ def interpret(self):
                     return
                 event = int(event)
                 event = self.model.events[event-1]
-            except:
+            except Exception:
                 print('Invalid input')
 
             self.event(event)
             self.print_menu()
 
 
-
 if __name__ == '__main__':
     this_folder = dirname(__file__)
     if len(sys.argv) != 2:
diff --git a/examples/hello_world/hello.py b/examples/hello_world/hello.py
index 5636d36b..a9485bdb 100755
--- a/examples/hello_world/hello.py
+++ b/examples/hello_world/hello.py
@@ -25,7 +25,3 @@ def main(debug=False):
 
 if __name__ == '__main__':
     main()
-
-
-
-
diff --git a/examples/pyFlies/experiment.py b/examples/pyFlies/experiment.py
index ebf6caf5..44e1ddac 100644
--- a/examples/pyFlies/experiment.py
+++ b/examples/pyFlies/experiment.py
@@ -17,4 +17,3 @@ def main(debug=False):
 
 if __name__ == '__main__':
     main()
-
diff --git a/examples/workflow/workflow.py b/examples/workflow/workflow.py
index 68046060..d26da258 100644
--- a/examples/workflow/workflow.py
+++ b/examples/workflow/workflow.py
@@ -25,4 +25,3 @@ def main(debug=False):
 
 if __name__ == '__main__':
     main()
-
diff --git a/requirements_dev.txt b/requirements_dev.txt
index 6f11ba06..da11f25c 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -1,5 +1,6 @@
 pytest
 flake8
+coverage
 jinja2
 mkdocs
 mike
diff --git a/tests/functional/test_regexp_with_groups.py b/tests/functional/test_regexp_with_groups.py
index 4d8a8654..79c7e3a0 100644
--- a/tests/functional/test_regexp_with_groups.py
+++ b/tests/functional/test_regexp_with_groups.py
@@ -14,12 +14,12 @@
 grammar = r"""
 Model: entries += Entry;
 Entry:
-    'data' '=' data=/\"(?ms){3}(.*?)\"{3}/
+    'data' '=' data=/(?ms)\"{3}(.*?)\"{3}/
 ;
 """
 grammar2 = r"""
 Model:
-    'data' '=' data=/\"(?ms){3}(.*?)\"{3}\s*\-(\w+)\-/
+    'data' '=' data=/(?ms)\"{3}(.*?)\"{3}\s*\-(\w+)\-/
 ;
 """
 
diff --git a/textx/commands/console.py b/textx/commands/console.py
index 724a0386..8b0404c9 100644
--- a/textx/commands/console.py
+++ b/textx/commands/console.py
@@ -13,7 +13,8 @@ def textx():
     class MyParser(argparse.ArgumentParser):
         """
         Custom argument parser for printing help message in case of an error.
-        See http://stackoverflow.com/questions/4042452/display-help-message-with-python-argparse-when-script-is-called-without-any-argu
+        See
+        http://stackoverflow.com/questions/4042452/display-help-message-with-python-argparse-when-script-is-called-without-any-argu
         """
         def error(self, message):
             sys.stderr.write('error: %s\n' % message)
diff --git a/textx/export.py b/textx/export.py
index 9efda0f3..fc991498 100644
--- a/textx/export.py
+++ b/textx/export.py
@@ -266,4 +266,4 @@ def _export_subgraph(m):
     else:
         _export(model)
 
-    f.write('\n}\n')
\ No newline at end of file
+    f.write('\n}\n')
diff --git a/textx/scoping/__init__.py b/textx/scoping/__init__.py
index d5060849..eb966de3 100644
--- a/textx/scoping/__init__.py
+++ b/textx/scoping/__init__.py
@@ -220,7 +220,7 @@ def load_model(
         return self.local_models.filename_to_model[filename]
 
     def _add_model(self, model):
-        filename =self.update_model_in_repo_based_on_filename(model)
+        filename = self.update_model_in_repo_based_on_filename(model)
         self.local_models.filename_to_model[filename] = model
 
     def update_model_in_repo_based_on_filename(self, model):
@@ -234,9 +234,9 @@ def update_model_in_repo_based_on_filename(self, model):
             for fn in self.all_models.filename_to_model:
                 if self.all_models.filename_to_model[fn] == model:
                     return fn
-            i=0
+            i = 0
             while self.all_models.has_model("anonymous{}".format(i)):
-                i+=1
+                i += 1
             myfilename = "anonymous{}".format(i)
             self.all_models.filename_to_model[myfilename] = model
         else:
@@ -245,7 +245,6 @@ def update_model_in_repo_based_on_filename(self, model):
                 self.all_models.filename_to_model[myfilename] = model
         return myfilename
 
-
     def pre_ref_resolution_callback(self, other_model):
         """
         (internal: used to store a model after parsing into the repository)
@@ -296,4 +295,3 @@ def get_all_models_including_attached_models(model):
     else:
         models = [model]
     return models
-
diff --git a/textx/scoping/providers.py b/textx/scoping/providers.py
index c7d4f325..9a0c843b 100644
--- a/textx/scoping/providers.py
+++ b/textx/scoping/providers.py
@@ -10,7 +10,7 @@
 import textx.scoping as scoping
 
 """
-This module defines scope providers to be used in conjunctions with a 
+This module defines scope providers to be used in conjunctions with a
 textx.metamodel meta model.
 
 See docs/scoping.md