add environment evaluation

test/14_before_all/cibuildwheel_test.py

@@ -13,7 +13,8 @@ def test():
     actual_wheels = utils.cibuildwheel_run(project_dir, add_env={
         # write python version information to a temporary file, this is
         # checked in setup.py
-        'CIBW_BEFORE_ALL': '''python -c "open('{project}/text_info.txt', 'w').write('sample text')"''',
+        'CIBW_BEFORE_ALL': '''python -c "import os;open('{project}/text_info.txt', 'w').write('sample text '+os.environ.get('TEST_VAL', ''))"''',
+        'CIBW_ENVIRONMENT': "TEST_VAL='123'"
     })
 
     # also check that we got the right wheels

test/14_before_all/setup.py

@@ -9,7 +9,7 @@ with open("text_info.txt") as f:
     stored_text = f.read()
 
 print("## stored text: " + stored_text)
-assert stored_text == "sample text"
+assert stored_text == "sample text 123"
 
 
 setup(