feat: Add planning feature to crew (#919)

* feat: add planning feature to crew

* feat: add test to planning handler and change to execute_async method

* docs: add planning parameter to the Core documentation

* docs: add planning docs

* fix: fix type checking issue

* fix: test and logic

tests/utilities/test_planning_handler.py

@@ -0,0 +1,68 @@
+from unittest.mock import patch
+
+import pytest
+
+from crewai.agent import Agent
+from crewai.task import Task
+from crewai.utilities.planning_handler import CrewPlanner, PlannerTaskPydanticOutput
+
+
+class TestCrewPlanner:
+    @pytest.fixture
+    def crew_planner(self):
+        tasks = [
+            Task(
+                description="Task 1",
+                expected_output="Output 1",
+                agent=Agent(role="Agent 1", goal="Goal 1", backstory="Backstory 1"),
+            ),
+            Task(
+                description="Task 2",
+                expected_output="Output 2",
+                agent=Agent(role="Agent 2", goal="Goal 2", backstory="Backstory 2"),
+            ),
+            Task(
+                description="Task 3",
+                expected_output="Output 3",
+                agent=Agent(role="Agent 3", goal="Goal 3", backstory="Backstory 3"),
+            ),
+        ]
+        return CrewPlanner(tasks)
+
+    def test_handle_crew_planning(self, crew_planner):
+        with patch.object(Task, "execute_sync") as execute:
+            execute.return_value = PlannerTaskPydanticOutput(
+                list_of_plans_per_task=["Plan 1", "Plan 2", "Plan 3"]
+            )
+            result = crew_planner._handle_crew_planning()
+            assert isinstance(result, PlannerTaskPydanticOutput)
+            assert len(result.list_of_plans_per_task) == len(crew_planner.tasks)
+            execute.assert_called_once()
+
+    def test_create_planning_agent(self, crew_planner):
+        agent = crew_planner._create_planning_agent()
+        assert isinstance(agent, Agent)
+        assert agent.role == "Task Execution Planner"
+
+    def test_create_planner_task(self, crew_planner):
+        planning_agent = Agent(
+            role="Planning Agent",
+            goal="Plan Step by Step Plan",
+            backstory="Master in Planning",
+        )
+        tasks_summary = "Summary of tasks"
+        task = crew_planner._create_planner_task(planning_agent, tasks_summary)
+
+        assert isinstance(task, Task)
+        assert task.description.startswith("Based on these tasks summary")
+        assert task.agent == planning_agent
+        assert (
+            task.expected_output
+            == "Step by step plan on how the agents can execute their tasks using the available tools with mastery"
+        )
+
+    def test_create_tasks_summary(self, crew_planner):
+        tasks_summary = crew_planner._create_tasks_summary()
+        assert isinstance(tasks_summary, str)
+        assert tasks_summary.startswith("\n                Task Number 1 - Task 1")
+        assert tasks_summary.endswith('"agent_tools": []\n                ')