Travis CI: Simplify the testing

.travis.yml

@@ -1,26 +1,5 @@
 language: python
-cache: pip
-python:
- - 2.7
- - 3.6
- #- nightly
- #- pypy
- #- pypy3
-matrix:
- allow_failures:
- - python: nightly
- - python: pypy
- - python: pypy3
-install:
- #- pip install -r requirements.txt
- - pip install flake8 # pytest # add another testing frameworks later
-before_script:
- # stop the build if there are Python syntax errors or undefined names
- - flake8 . --count --select=E9,F63,F72,F82 --show-source --statistics
- # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
- - flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
-script:
- - true # pytest --capture=sys # add other tests here
-notifications:
- on_success: change
- on_failure: change # `always` will be the setting once code changes slow down
+dist: xenial # required for Python >= 3.7
+python: 3.7
+install: pip install flake8
+script: flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics