Add travis pip wheel caching

.travis.yml

@@ -2,6 +2,10 @@ language: python
 
 sudo: false
 
+cache:
+  directories:
+    - $HOME/.wheelhouse
+
 env:
     - TOX_ENV=py27-flake8
     - TOX_ENV=py27-docs
@@ -28,6 +32,7 @@ env:
 
 install:
   - pip install tox
+  - export WHEEL_DIR=$HOME/.wheelhouse/$TOX_ENV
 
 script:
     - tox -e $TOX_ENV

custom_pip_install.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+if [[ "$@" == "djangorestframework" ]]; then
+  # Caching djangorestframework package would invalidate Travis cache on every build
+  pip install "$@"
+else
+  # Try to install from cache
+  pip install --no-index --find-links=$WHEEL_DIR "$@"
+  EXIT_STATUS=$?
+  # If that fails, try to make a wheel
+  if [ $EXIT_STATUS -ne 0 ]; then
+    pip wheel --wheel-dir=$WHEEL_DIR "$@"
+    EXIT_STATUS=$?
+    # If that fails, install wheel and make wheel
+    if [ $EXIT_STATUS -ne 0 ]; then
+        pip install wheel==0.24.0
+        pip wheel --wheel-dir=$WHEEL_DIR "$@"
+    fi
+    # Install from cache
+    pip install --no-index --find-links=$WHEEL_DIR "$@"
+  fi
+fi

tox.ini

@@ -6,6 +6,9 @@ envlist =
        {py27,py32,py33,py34}-django{17,18beta}
 
 [testenv]
+install_command =
+       {toxinidir}/custom_pip_install.sh {packages}
+
 commands = ./runtests.py --fast
 setenv =
        PYTHONDONTWRITEBYTECODE=1