chore(generator): enable system tests

[ohmayr]

No description provided.

[gemini-code-assist]

Code Review

This pull request implements the system test session in noxfile.py to run the system test suite against Showcase, controlled by the RUN_SYSTEM_TESTS environment variable. The feedback suggests improving the parsing of this environment variable by failing fast and raising a ValueError if an invalid or empty value is provided, rather than silently falling back to a default.

[gemini-code-assist]

When parsing the RUN_SYSTEM_TESTS environment variable, if a user explicitly sets an invalid value (such as whitespace-only or an invalid boolean string), we should fail fast and raise an error to notify them of the invalid configuration rather than silently falling back to a default value.

    run_env = os.environ.get("RUN_SYSTEM_TESTS", "true")
    if not run_env.strip():
        raise ValueError("RUN_SYSTEM_TESTS cannot be empty or whitespace-only")
    run_system_tests = run_env.strip().lower()
    if run_system_tests not in ["true", "false"]:
        raise ValueError(f"Invalid value for RUN_SYSTEM_TESTS: {run_env}")
    if run_system_tests == "false":
        session.skip("RUN_SYSTEM_TESTS is set to false, skipping")

References

1. When parsing environment variables, if a user explicitly sets an invalid value (such as whitespace-only), fail fast and raise an error to notify them of the invalid configuration rather than silently falling back to a default value.