Run each test using a temporary directory (#217)

test/06_docker_images/cibuildwheel_test.py

@@ -7,7 +7,7 @@ def test():
     if utils.platform != 'linux':
         pytest.skip('the test is only relevant to the linux build')
 
-    utils.cibuildwheel_run(project_dir, add_env={
+    actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
         'CIBW_MANYLINUX_X86_64_IMAGE': 'dockcross/manylinux2010-x64',
         'CIBW_MANYLINUX_I686_IMAGE': 'dockcross/manylinux1-x86',
         'CIBW_BEFORE_BUILD': '/opt/python/cp36-cp36m/bin/pip install -U auditwheel',  # Currently necessary on dockcross images to get auditwheel 2.1 supporting AUDITWHEEL_PLAT
@@ -17,5 +17,4 @@ def test():
     # also check that we got the right wheels built
     expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
                        if '-manylinux2010_i686' not in w]
-    actual_wheels = os.listdir('wheelhouse')
     assert set(actual_wheels) == set(expected_wheels)