Add test_plot_environment dependencies (#30)

This commit aims to resolve all dependency issues in the
matplotlib.animation.FuncAnimation when running the
test_plot_environment script.

A toolchain called libav-tools is installed in travis-ci,
and an if-else script checks if display is found. If not,
then it uses the default 'Agg' backend.

Moreover, the mock==2.0.0 package is also used during
tests as shown in setup.py.

Author: ljvmiranda921
E-mail: ljvmiranda@gmail.com

.travis.yml

@@ -22,7 +22,9 @@ deploy:
     repo: ljvmiranda921/pyswarms
     tags: true
 install: 
-  - "pip install -U tox-travis"
+  - sudo apt-get update
+  - sudo apt-get install libav-tools
+  - pip install -U tox-travis
 language: python
 python:
   - 3.6

setup.py

@@ -17,6 +17,7 @@
     'scipy>=0.17.0',
     'numpy>=1.13.0',
     'matplotlib>=1.3.1',
+    'mock==2.0.0',
 ]
 
 setup_requirements = [
@@ -29,6 +30,7 @@
     'scipy>=0.17.0',
     'numpy>=1.13.0',
     'matplotlib>=1.3.1',
+    'mock==2.0.0',
 ]
 
 setup(

tests/utils/environments/test_plot_environment.py

@@ -7,12 +7,18 @@
 from __future__ import print_function
 
 # Import modules
+import os
 import unittest
 import numpy as np
 from mock import Mock
+import matplotlib as mpl
 from matplotlib.axes._subplots import SubplotBase
 from matplotlib.animation import FuncAnimation
 
+# Fix for display
+if os.environ.get('DISPLAY','') == '':
+    mpl.use('Agg')
+
 # Import from package
 from pyswarms.utils.environments import PlotEnvironment
 from pyswarms.single import GlobalBestPSO