Update .travis.yml file to use tox as script for running tests

.travis.yml

@@ -1,64 +1,23 @@
 language: python
-sudo: false
-python:
-- 2.7
-- 3.5
-- 3.6
-# - "pypy-5.3.1"
-before_install:
-- |
-  if [ "$TRAVIS_PYTHON_VERSION" = "pypy" ]; then
-    export PYENV_ROOT="$HOME/.pyenv"
-    if [ -f "$PYENV_ROOT/bin/pyenv" ]; then
-      cd "$PYENV_ROOT" && git pull
-    else
-      rm -rf "$PYENV_ROOT" && git clone --depth 1 https://github.com/yyuu/pyenv.git "$PYENV_ROOT"
-    fi
-    export PYPY_VERSION="4.0.1"
-    "$PYENV_ROOT/bin/pyenv" install "pypy-$PYPY_VERSION"
-    virtualenv --python="$PYENV_ROOT/versions/pypy-$PYPY_VERSION/bin/python" "$HOME/virtualenvs/pypy-$PYPY_VERSION"
-    source "$HOME/virtualenvs/pypy-$PYPY_VERSION/bin/activate"
-  fi
-install:
-- |
-  if [ "$TEST_TYPE" = build ]; then
-    pip install -e .[test]
-    python setup.py develop
-  elif [ "$TEST_TYPE" = lint ]; then
-    pip install flake8
-  elif [ "$TEST_TYPE" = mypy ]; then
-    pip install mypy
-  fi
-script:
-- |
-  if [ "$TEST_TYPE" = lint ]; then
-    echo "Checking Python code lint."
-    flake8 graphene
-    exit
-  elif [ "$TEST_TYPE" = mypy ]; then
-    echo "Checking Python types."
-    mypy graphene
-    exit
-  elif [ "$TEST_TYPE" = build ]; then
-    py.test --cov=graphene graphene examples
-  fi
-after_success:
-- |
-  if [ "$TEST_TYPE" = build ]; then
-      coveralls
-  fi
-env:
-  matrix:
-  - TEST_TYPE=build
+python: 3.6
+env:  # These should match the tox env list.
+    - TOXENV=flake8
+    - TOXENV=py27
+    - TOXENV=py33
+    - TOXENV=py34
+    - TOXENV=py35
+    - TOXENV=py36
+    - TOXENV=pypy
+    - TOXENV=pre-commit
   global:
     secure: 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
-matrix:
-  fast_finish: true
-  include:
-  - python: '2.7'
-    env: TEST_TYPE=lint
-  - python: '3.6'
-    env: TEST_TYPE=mypy
+install: pip install coveralls tox flake8 mypy
+script: tox
+after_success: coveralls
+cache:
+    directories:
+        - $HOME/.cache/pip
+        - $HOME/.cache/pre-commit
 deploy:
   provider: pypi
   user: syrusakbary