When working with environment variables, follow consistent naming conventions, properly check for their presence, and preserve the environment when spawning subprocesses. Use standard naming patterns (e.g., `OPENSSL_VERSION_OVERRIDE` instead of `OPEN_SSL_VERSION_OVERRIDE`), check both command-line arguments and environment variables for configuration options, and always copy the current environment when passing custom environments to subprocess calls. Example of proper environment handling: ```python # Good: Standard naming convention openssl_version = os.getenv("OPENSSL_VERSION_OVERRIDE", "3.0.8") # Good: Check both argument and environment variable summarize_failures = args.summarize_failures or os.getenv("SUMMARIZE_FAILURES") == "1" # Good: Preserve current environment when spawning subprocess env = os.environ.copy() if list_of_tests or no_exit or tests_per_invocation: env['SUMMARIZE_FAILURES'] = '0' env['NO_DUPLICATING_HEADERS'] = '1' res = subprocess.run(test_cmd, stdout=unittest_stdout, stderr=unittest_stderr, timeout=timeout, env=env) ``` This ensures configuration consistency, prevents loss of important environment settings, and maintains predictable behavior across different execution contexts.