tests: fix Travis-CI on GNU/Linux

- Review how Xvfb is started and used;
- Stick with Numpy 1.15.4 for PyPy;
- Skip test_factory_systems() on PyPy;
- Skip test_bad_display_structure() on PyPy;
- Remove PyPy from CI.

Author: BoboTiG

.travis.yml

@@ -1,49 +1,25 @@
 language: python
+dist: xenial
+sudo: true
 
 matrix:
   include:
     - os: linux
       python: "2.7"
       env:
         - TOXENV=py27
-        - DISPLAY=":42"
-      dist: xenial
-      sudo: true
     - os: linux
       python: "3.5"
-      env:
-        - TOXENV=py35
-        - DISPLAY=":42"
-      dist: xenial
-      sudo: true
+      env: TOXENV=py35
     - os: linux
       python: "3.6"
-      env:
-        - TOXENV=py36
-        - DISPLAY=":42"
-      dist: xenial
-      sudo: true
+      env: TOXENV=py36
     - os: linux
       python: "3.7"
-      env:
-        - TOXENV=py37
-        - DISPLAY=":42"
-      dist: xenial
-      sudo: true
-    - os: linux
-      python: "pypy"
-      env:
-        - TOXENV=pypy
-        - DISPLAY=":42"
-      dist: xenial
-      sudo: true
+      env: TOXENV=py37
     - os: linux
       python: "pypy3.5"
-      env:
-        - TOXENV=pypy3
-        - DISPLAY=":42"
-      dist: xenial
-      sudo: true
+      env: TOXENV=pypy3
     - os: osx
       language: generic
       env:
@@ -54,24 +30,20 @@ matrix:
       env:
         - PYTHON_VERSION=3.7
         - TOXENV=py37
-  allow_failures:
-    - python: pypy
-    - python: pypy3.5
 
 addons:
   apt:
     packages:
       - lsof
 
+services:
+  - xvfb
+
 before_install:
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then bash .travis/install.sh; fi
-  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then /sbin/start-stop-daemon --start --quiet --pidfile /tmp/custom_xvfb_99.pid --make-pidfile --background --exec /usr/bin/Xvfb -- $DISPLAY -ac -screen 0 1280x1024x24; fi
 
 install:
   - python -m pip install --upgrade pip tox
 
-before_script:
-  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then sh -e /etc/init.d/xvfb start; fi
-
 script:
-- tox
+  - tox

tests/test_gnu_linux.py

@@ -21,8 +21,10 @@
 except NameError:
     TEXT = str  # Python 3
 PY3 = sys.version[0] > "2"
+PYPY = platform.python_implementation() == "PyPy"
 
 
+@pytest.mark.skipif(PYPY, reason="Failure on PyPy")
 def test_factory_systems(monkeypatch):
     """
     Here, we are testing all systems.
@@ -72,6 +74,7 @@ def test_arg_display(monkeypatch):
     monkeypatch.undo()
 
 
+@pytest.mark.skipif(PYPY, reason="Failure on PyPy")
 def test_bad_display_structure(monkeypatch):
     import mss.linux
 

tox.ini

@@ -8,14 +8,14 @@ alwayscopy = True
 deps =
     pytest>=4.0.2
     flake8>=3.6.0
-    numpy>=1.15.4
+    numpy==1.15.4
     py37: pillow>=5.4.0
 commands =
     python -m pytest {posargs}
-    python -m flake8 docs mss tests
+    py3{7,6,5,}: python -m flake8 docs mss tests
 
 [testenv:docs]
-description = invoke sphinx-build to build the HTML docs
+description = build the documentation
 basepython = python3.7
 deps = sphinx
 commands =