cleanup environment variables between tests (#30167)

conftest.py

@@ -1,10 +1,28 @@
+import os
 import pytest
 
 from openpilot.common.prefix import OpenpilotPrefix
 
 
 @pytest.fixture(scope="function", autouse=True)
-def global_setup_and_teardown():
+def openpilot_function_fixture():
+  starting_env = dict(os.environ)
+
   # setup a clean environment for each test
   with OpenpilotPrefix():
     yield
+
+  os.environ.clear()
+  os.environ.update(starting_env)
+
+
+# If you use setUpClass, the environment variables won't be cleared properly,
+# so we need to hook both the function and class pytest fixtures
+@pytest.fixture(scope="class", autouse=True)
+def openpilot_class_fixture():
+  starting_env = dict(os.environ)
+
+  yield
+
+  os.environ.clear()
+  os.environ.update(starting_env)