feat: implement task modification functionality in TaskWarrior server

- Added `modify_task` method to allow modification of tasks based on a filter expression, supporting parameters for project, priority, due date, description, and tags.
- Implemented validation for modification parameters, ensuring at least one parameter is provided and that priority and tag formats are correct.
- Introduced corresponding tests to validate the functionality of task modifications, including edge cases for invalid inputs and multiple modifications.
- Enhanced docstrings for clarity and detailed usage examples.

1 files changed, 165 insertions, 0 deletions

diff --git a/servers/taskwarrior/tests/test_server.py b/servers/taskwarrior/tests/test_server.py
index 97f7268..601a535 100644
--- a/servers/taskwarrior/tests/test_server.py
+++ b/servers/taskwarrior/tests/test_server.py
@@ -212,3 +212,168 @@ class TestTaskWarriorServer:
             await taskwarrior_server.manage_context("set")
         
         assert "Context name is required" in str(exc_info.value)
+    
+    @pytest.mark.asyncio
+    async def test_modify_task_project(self, taskwarrior_server):
+        """Test modifying a task's project."""
+        mock_output = "Modified 1 task."
+        
+        with patch.object(
+            taskwarrior_server, '_run_task_command',
+            new_callable=AsyncMock,
+            return_value=(mock_output, '', 0)
+        ):
+            result = await taskwarrior_server.modify_task(
+                "uuid:test-uuid-123",
+                project="NewProject"
+            )
+            assert result["filter_expr"] == "uuid:test-uuid-123"
+            assert result["modifications"]["project"] == "NewProject"
+    
+    @pytest.mark.asyncio
+    async def test_modify_task_priority(self, taskwarrior_server):
+        """Test modifying a task's priority."""
+        mock_output = "Modified 1 task."
+        
+        with patch.object(
+            taskwarrior_server, '_run_task_command',
+            new_callable=AsyncMock,
+            return_value=(mock_output, '', 0)
+        ):
+            result = await taskwarrior_server.modify_task(
+                "uuid:test-uuid-123",
+                priority="H"
+            )
+            assert result["modifications"]["priority"] == "H"
+    
+    @pytest.mark.asyncio
+    async def test_modify_task_clear_priority(self, taskwarrior_server):
+        """Test clearing a task's priority."""
+        mock_output = "Modified 1 task."
+        
+        with patch.object(
+            taskwarrior_server, '_run_task_command',
+            new_callable=AsyncMock,
+            return_value=(mock_output, '', 0)
+        ):
+            result = await taskwarrior_server.modify_task(
+                "uuid:test-uuid-123",
+                priority=""
+            )
+            assert result["modifications"]["priority"] is None
+    
+    @pytest.mark.asyncio
+    async def test_modify_task_due(self, taskwarrior_server):
+        """Test modifying a task's due date."""
+        mock_output = "Modified 1 task."
+        
+        with patch.object(
+            taskwarrior_server, '_run_task_command',
+            new_callable=AsyncMock,
+            return_value=(mock_output, '', 0)
+        ):
+            result = await taskwarrior_server.modify_task(
+                "uuid:test-uuid-123",
+                due="tomorrow"
+            )
+            assert result["modifications"]["due"] == "tomorrow"
+    
+    @pytest.mark.asyncio
+    async def test_modify_task_description(self, taskwarrior_server):
+        """Test modifying a task's description."""
+        mock_output = "Modified 1 task."
+        
+        with patch.object(
+            taskwarrior_server, '_run_task_command',
+            new_callable=AsyncMock,
+            return_value=(mock_output, '', 0)
+        ):
+            result = await taskwarrior_server.modify_task(
+                "uuid:test-uuid-123",
+                description="New description"
+            )
+            assert result["modifications"]["description"] == "New description"
+    
+    @pytest.mark.asyncio
+    async def test_modify_task_tags(self, taskwarrior_server):
+        """Test modifying a task's tags."""
+        mock_output = "Modified 1 task."
+        
+        with patch.object(
+            taskwarrior_server, '_run_task_command',
+            new_callable=AsyncMock,
+            return_value=(mock_output, '', 0)
+        ):
+            result = await taskwarrior_server.modify_task(
+                "uuid:test-uuid-123",
+                tags=["+urgent", "-later"]
+            )
+            assert result["modifications"]["tags"] == ["+urgent", "-later"]
+    
+    @pytest.mark.asyncio
+    async def test_modify_task_multiple_fields(self, taskwarrior_server):
+        """Test modifying multiple fields at once."""
+        mock_output = "Modified 1 task."
+        
+        with patch.object(
+            taskwarrior_server, '_run_task_command',
+            new_callable=AsyncMock,
+            return_value=(mock_output, '', 0)
+        ):
+            result = await taskwarrior_server.modify_task(
+                "+work",
+                project="Work",
+                priority="H",
+                tags=["+urgent"]
+            )
+            assert result["filter_expr"] == "+work"
+            assert result["modifications"]["project"] == "Work"
+            assert result["modifications"]["priority"] == "H"
+            assert result["modifications"]["tags"] == ["+urgent"]
+    
+    @pytest.mark.asyncio
+    async def test_modify_task_no_modifications(self, taskwarrior_server):
+        """Test that modifying without any parameters raises ValueError."""
+        with pytest.raises(ValueError) as exc_info:
+            await taskwarrior_server.modify_task("uuid:test-uuid-123")
+        
+        assert "At least one modification parameter must be provided" in str(exc_info.value)
+    
+    @pytest.mark.asyncio
+    async def test_modify_task_invalid_priority(self, taskwarrior_server):
+        """Test that invalid priority raises ValueError."""
+        with pytest.raises(ValueError) as exc_info:
+            await taskwarrior_server.modify_task(
+                "uuid:test-uuid-123",
+                priority="X"
+            )
+        
+        assert "Priority must be H, M, or L" in str(exc_info.value)
+    
+    @pytest.mark.asyncio
+    async def test_modify_task_invalid_tag_format(self, taskwarrior_server):
+        """Test that tags without +/- prefix raise ValueError."""
+        with pytest.raises(ValueError) as exc_info:
+            await taskwarrior_server.modify_task(
+                "uuid:test-uuid-123",
+                tags=["invalidtag"]
+            )
+        
+        assert "Tags must start with + or -" in str(exc_info.value)
+    
+    @pytest.mark.asyncio
+    async def test_modify_task_with_filter_expression(self, taskwarrior_server):
+        """Test modifying tasks with complex filter expression."""
+        mock_output = "Modified 2 tasks."
+        
+        with patch.object(
+            taskwarrior_server, '_run_task_command',
+            new_callable=AsyncMock,
+            return_value=(mock_output, '', 0)
+        ):
+            result = await taskwarrior_server.modify_task(
+                "project:Home status:pending",
+                priority="M"
+            )
+            assert result["filter_expr"] == "project:Home status:pending"
+            assert result["modifications"]["priority"] == "M"