Add ability for test projects to have custom env vars

run_tests.py

@@ -1,5 +1,5 @@
 from __future__ import print_function
-import os, sys, subprocess
+import os, sys, subprocess, shutil, json
 from glob import glob
 
 # move cwd to the project root
@@ -14,7 +14,22 @@ if len(test_projects) == 0:
 print('Testing projects:', test_projects)
 
 for project_path in test_projects:
-    subprocess.check_call(['cibuildwheel', project_path])
-    print('%s built successfully.' % project_path)
+    # load project settings into environment
+    env = os.environ.copy()
+    env_file = os.path.join(project_path, 'environment.json')
+    if os.path.exists(env_file):
+        with open(env_file) as f:
+            env.update(json.load(f))
+
+    # run the build
+    subprocess.check_call(['cibuildwheel', project_path], env=env)
+    wheels = glob('wheelhouse/*.whl')
+    print('%s built successfully. %i wheels built.' % (project_path, len(wheels)))
+
+    # check wheels were actually built
+    assert len(wheels) >= 4
+
+    # clean up
+    shutil.rmtree('wheelhouse')
 
 print('%d projects built successfully.' % len(test_projects))