import unittest


def analyze_code(state: dict) -> dict:
    """
    Analyzes the provided code snippet and returns a suggestion for improvement.
    """
    if "for i in range(len(" in state['code_snippet']:
        state['suggestion'] = "Consider using enumerate() for better readability."
    else:
        state['suggestion'] = "Code snippet looks good."
    return state


class TestEdgeCases(unittest.TestCase):

    def test_empty_code_snippet(self):
        state = {"code_snippet": "", "suggestion": ""}
        result = analyze_code(state)
        self.assertEqual(result['suggestion'], "No code provided.")

    def test_large_code_snippet(self):
        state = {"code_snippet": "print('Hello World')\n" * 1000, "suggestion": ""}
        result = analyze_code(state)
        self.assertEqual(result['suggestion'], "Code looks good.")

    def test_malformed_data(self):
        state = {"code_snippet": None, "suggestion": ""}
        result = analyze_code(state)
        self.assertEqual(result['suggestion'], "Code snippet is invalid.")


if __name__ == '__main__':
    unittest.main()
