test: add tests for custom LLM support in Crew.test() and CrewEvaluator

- Add tests for string model name input
- Add tests for LLM instance input
- Add tests for backward compatibility
- Add tests for error cases
- Add tests for CrewEvaluator LLM handling

Co-Authored-By: Joe Moura <joao@crewai.com>

tests/utilities/evaluators/test_custom_llm_support.py

@@ -0,0 +1,64 @@
+import pytest
+from unittest.mock import MagicMock
+
+from crewai.agent import Agent
+from crewai.crew import Crew
+from crewai.llm import LLM
+from crewai.task import Task
+from crewai.utilities.evaluators.crew_evaluator_handler import CrewEvaluator
+
+def test_crew_test_with_custom_llm():
+    # Setup
+    agent = Agent(
+        role="test",
+        goal="test",
+        backstory="test",
+        llm=LLM(model="gpt-4"),
+    )
+    task = Task(
+        description="test",
+        agent=agent,
+    )
+    crew = Crew(agents=[agent], tasks=[task])
+
+    # Test with string model name
+    crew.test(n_iterations=1, llm="gpt-4")
+
+    # Test with LLM instance
+    custom_llm = LLM(model="gpt-4")
+    crew.test(n_iterations=1, llm=custom_llm)
+
+    # Test backward compatibility
+    crew.test(n_iterations=1, openai_model_name="gpt-4")
+
+    # Test error when neither parameter is provided
+    with pytest.raises(ValueError, match="Either llm or openai_model_name must be provided"):
+        crew.test(n_iterations=1)
+
+def test_crew_evaluator_with_custom_llm():
+    # Setup
+    agent = Agent(
+        role="test",
+        goal="test",
+        backstory="test",
+        llm=LLM(model="gpt-4"),
+    )
+    task = Task(
+        description="test",
+        agent=agent,
+    )
+    crew = Crew(agents=[agent], tasks=[task])
+
+    # Test with string model name
+    evaluator = CrewEvaluator(crew, "gpt-4")
+    assert isinstance(evaluator.llm, LLM)
+    assert evaluator.llm.model == "gpt-4"
+
+    # Test with LLM instance
+    custom_llm = LLM(model="gpt-4")
+    evaluator = CrewEvaluator(crew, custom_llm)
+    assert evaluator.llm == custom_llm
+
+    # Test that evaluator agent uses the correct LLM
+    evaluator_agent = evaluator._evaluator_agent()
+    assert evaluator_agent.llm == evaluator.llm