Address GitHub review feedback for selective execution feature

- Enhanced error messages with specific action and available tags information
- Improved type safety by removing problematic TaskSelectorType alias
- Added comprehensive tag validation with normalization in Task class
- Fixed edge case handling for untagged tasks in tag selector
- Added test for invalid tag types validation
- Maintained backward compatibility while optimizing performance

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

test_selective_execution.py

@@ -0,0 +1,115 @@
+import pytest
+from crewai import Agent, Crew, Task, Process
+
+def test_selective_execution_basic():
+    """Test basic selective execution functionality without VCR."""
+    
+    researcher = Agent(
+        role="Researcher",
+        goal="Research topics",
+        backstory="Expert researcher"
+    )
+    
+    writer = Agent(
+        role="Writer", 
+        goal="Write content",
+        backstory="Expert writer"
+    )
+    
+    forecast_task = Task(
+        description="Analyze forecast data",
+        expected_output="Forecast analysis",
+        agent=researcher,
+        tags=["forecast", "analysis"]
+    )
+    
+    news_task = Task(
+        description="Summarize news",
+        expected_output="News summary", 
+        agent=writer,
+        tags=["news", "summary"]
+    )
+    
+    crew = Crew(
+        agents=[researcher, writer],
+        tasks=[forecast_task, news_task],
+        task_selector=Crew.create_tag_selector()
+    )
+    
+    assert crew.task_selector is not None
+    
+    selector = crew.task_selector
+    
+    inputs = {"action": "forecast"}
+    assert selector(inputs, forecast_task) == True
+    assert selector(inputs, news_task) == False
+    
+    inputs = {"action": "news"}
+    assert selector(inputs, forecast_task) == False
+    assert selector(inputs, news_task) == True
+    
+    print("All selective execution tests passed!")
+
+def test_selective_process_validation():
+    """Test that selective process requires task_selector."""
+    from pydantic import ValidationError
+    
+    researcher = Agent(
+        role="Researcher",
+        goal="Research topics", 
+        backstory="Expert researcher"
+    )
+    
+    task = Task(
+        description="Test task",
+        expected_output="Test output",
+        agent=researcher
+    )
+    
+    try:
+        crew = Crew(
+            agents=[researcher],
+            tasks=[task],
+            process=Process.selective
+        )
+        assert False, "Should have raised ValidationError"
+    except ValidationError as e:
+        assert "task_selector" in str(e)
+        print("Validation error correctly raised for missing task_selector")
+
+def test_tag_selector_edge_cases():
+    """Test edge cases for tag selector."""
+    
+    researcher = Agent(
+        role="Researcher",
+        goal="Research topics",
+        backstory="Expert researcher"
+    )
+    
+    tagged_task = Task(
+        description="Tagged task",
+        expected_output="Output",
+        agent=researcher,
+        tags=["test"]
+    )
+    
+    untagged_task = Task(
+        description="Untagged task", 
+        expected_output="Output",
+        agent=researcher
+    )
+    
+    selector = Crew.create_tag_selector()
+    
+    assert selector({}, tagged_task) == True
+    assert selector({}, untagged_task) == True
+    
+    assert selector({"action": "anything"}, untagged_task) == True
+    
+    print("Edge case tests passed!")
+
+if __name__ == "__main__":
+    test_selective_execution_basic()
+    test_selective_process_validation()
+    test_tag_selector_edge_cases()
+    print("All tests completed successfully!")