add 32bit test

.travis.yml

@@ -1,5 +1,7 @@
 language: python
-cache: pip
+cache:
+ - pip
+ - ccache
 os:
   - linux
 python:
@@ -32,6 +34,21 @@ matrix:
       script:
         - flake8 .
 
+    - stage: test
+      dist: bionic
+      env: C_COMPILER=i686-linux-gnu-gcc CFLAGS=-m32
+      addons:
+        apt:
+          packages:
+            - gcc-i686-linux-gnu
+      before_install:
+              - |
+                  sudo dpkg --add-architecture i386 && sudo apt update \
+                  && sudo apt install -y python3.7:i386 python3.7-minimal:i386 python3.7-dev:i386 python3-pip liblzo2-dev:i386
+              - |
+                  export PYTHON=python3.7 && sudo -H $PYTHON -m pip install -U pip \
+                  && sudo -H $PYTHON -m pip install wheel virtualenv setuptools
+              - $PYTHON -m virtualenv ${HOME}/.env && source ${HOME}/.env/bin/activate
     - stage: deploy
       python: '3.5'
       services:
@@ -65,9 +82,10 @@ addons:
       - liblzo2-dev
 
 install:
+  - if [ -n "${C_COMPILER}" ]; then export CC="${C_COMPILER}"; fi
   - $PYTHON -m pip install Cython nose numpy python-lzo six
   - $PYTHON setup.py build_ext --inplace
   - $PYTHON setup.py install
 
 script:
-  - nosetests
+  - $PYTHON -m nose