def test_core_not_in_toml(default_config, temp_toml_file):
    """Test loading configuration when the core section is not in the TOML file.

    default values should be used for the missing sections.
    """
    with open(temp_toml_file, 'w', encoding='utf-8') as toml_file:
        toml_file.write("""
[llm]
model = "test-model"

[agent]
enable_prompt_extensions = true

[sandbox]
timeout = 1
base_container_image = "custom_image"
user_id = 1001

[security]
security_analyzer = "semgrep"
""")

    load_from_toml(default_config, temp_toml_file)
    assert default_config.get_llm_config().model == 'test-model'
    assert default_config.get_agent_config().enable_prompt_extensions is True
    assert default_config.sandbox.base_container_image == 'custom_image'
    assert default_config.sandbox.user_id == 1001
    assert default_config.security.security_analyzer == 'semgrep'
Test loading configuration when the core section is not in the TOML file.

    default values should be used for the missing sections.
    
tests/unit/test_config.py