Update test_case_generator.py

test_case_generator.py

@@ -10,7 +10,7 @@ class TestCaseGenerator:
     def __init__(self, api_key=None):
         # Allow API key to be passed in or read from environment
         if api_key:
-            os.environ["OPENAI_API_KEY"] = api_key
+            os.environ["OPENAI_API_KEY"] = os.getenv('OPENAI_API_KEY')
         
         # Predefined question types
         self.available_question_types = [