Fix #2558: Add LiteAgent as a lightweight agent implementation

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

tests/lite_agent_test.py

@@ -0,0 +1,125 @@
+"""Test LiteAgent creation and execution basic functionality."""
+
+import os
+from unittest.mock import patch, MagicMock
+
+import pytest
+
+from crewai import LiteAgent, Task
+from crewai.llm import LLM
+from crewai.tools import tool
+
+
+def test_lite_agent_creation():
+    """Test creating a LiteAgent with basic properties."""
+    agent = LiteAgent(role="test role", goal="test goal", backstory="test backstory")
+
+    assert agent.role == "test role"
+    assert agent.goal == "test goal"
+    assert agent.backstory == "test backstory"
+    assert agent.tools == []
+
+
+def test_lite_agent_default_values():
+    """Test default values for LiteAgent."""
+    agent = LiteAgent(role="test role", goal="test goal", backstory="test backstory")
+    assert agent.llm.model == "gpt-4o-mini"
+    assert agent.max_iter == 20
+    assert agent.max_retry_limit == 2
+
+
+def test_custom_llm():
+    """Test creating a LiteAgent with a custom LLM string."""
+    agent = LiteAgent(
+        role="test role", goal="test goal", backstory="test backstory", llm="gpt-4"
+    )
+    assert agent.llm.model == "gpt-4"
+
+
+def test_custom_llm_with_langchain():
+    """Test creating a LiteAgent with a langchain LLM."""
+    mock_langchain_llm = MagicMock()
+    mock_langchain_llm.model_name = "gpt-4"
+    
+    agent = LiteAgent(
+        role="test role",
+        goal="test goal",
+        backstory="test backstory",
+        llm=mock_langchain_llm,
+    )
+
+    assert agent.llm.model == "gpt-4"
+
+
+@patch("crewai.agents.crew_agent_executor.CrewAgentExecutor.invoke")
+def test_lite_agent_execute_task(mock_invoke):
+    """Test executing a task with a LiteAgent."""
+    mock_invoke.return_value = {"output": "The area of a circle with radius 5 cm is 78.54 square centimeters."}
+    
+    agent = LiteAgent(
+        role="Math Tutor",
+        goal="Solve math problems accurately",
+        backstory="You are an experienced math tutor with a knack for explaining complex concepts simply.",
+    )
+
+    task = Task(
+        description="Calculate the area of a circle with radius 5 cm.",
+        expected_output="The calculated area of the circle in square centimeters.",
+        agent=agent,
+    )
+
+    result = agent.execute_task(task)
+
+    assert result is not None
+    assert "square centimeters" in result.lower()
+    mock_invoke.assert_called_once()
+
+
+@patch("crewai.agents.crew_agent_executor.CrewAgentExecutor.invoke")
+def test_lite_agent_execution(mock_invoke):
+    """Test executing a simple task."""
+    mock_invoke.return_value = {"output": "1 + 1 = 2"}
+    
+    agent = LiteAgent(
+        role="test role",
+        goal="test goal",
+        backstory="test backstory",
+    )
+
+    task = Task(
+        description="How much is 1 + 1?",
+        agent=agent,
+        expected_output="the result of the math operation.",
+    )
+
+    output = agent.execute_task(task)
+    assert "2" in output
+    mock_invoke.assert_called_once()
+
+
+@patch("crewai.agents.crew_agent_executor.CrewAgentExecutor.invoke")
+def test_lite_agent_execution_with_tools(mock_invoke):
+    """Test executing a task with tools."""
+    mock_invoke.return_value = {"output": "3 times 4 is 12"}
+    
+    @tool
+    def multiplier(first_number: int, second_number: int) -> float:
+        """Useful for when you need to multiply two numbers together."""
+        return first_number * second_number
+
+    agent = LiteAgent(
+        role="test role",
+        goal="test goal",
+        backstory="test backstory",
+        tools=[multiplier],
+    )
+
+    task = Task(
+        description="What is 3 times 4?",
+        agent=agent,
+        expected_output="The result of the multiplication.",
+    )
+    
+    output = agent.execute_task(task)
+    assert "12" in output
+    mock_invoke.assert_called_once()