Implement task tracker CLI with JSON persistence and tests

.gitignore

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+__pycache__/
+*.pyc
+.venv/
+.pytest_cache/

README.md

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 # Rahul-s-LAB
-My LAB respository..
+
+A complete, working lab solution implemented as a **Task Tracker CLI**.
+
+## Features
+- Add tasks
+- List tasks
+- Mark tasks as complete
+- Delete tasks
+- JSON file persistence
+
+## Quickstart
+```bash
+python -m venv .venv
+source .venv/bin/activate
+pip install -e . pytest
+```
+
+Run commands:
+```bash
+labtracker add "Write the complete code"
+labtracker list
+labtracker done 1
+labtracker delete 1
+```
+
+Use a custom database file:
+```bash
+labtracker --db ./my_tasks.json add "Sample"
+```
+
+## Test
+```bash
+pytest
+```

pyproject.toml

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+[build-system]
+requires = ["setuptools>=68", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "rahul-lab"
+version = "0.1.0"
+description = "A complete command-line lab task tracker solution"
+readme = "README.md"
+requires-python = ">=3.10"
+dependencies = []
+
+[project.scripts]
+labtracker = "src.main:main"
+
+[tool.pytest.ini_options]
+pythonpath = ["."]
+testpaths = ["tests"]

src/main.py

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+from __future__ import annotations
+
+import argparse
+from pathlib import Path
+
+from src.tracker import TaskTracker
+
+
+def _build_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser(description="Lab Task Tracker")
+    parser.add_argument(
+        "--db",
+        default=".lab/tasks.json",
+        help="Path to the tracker JSON file (default: .lab/tasks.json)",
+    )
+
+    subparsers = parser.add_subparsers(dest="command", required=True)
+
+    add_parser = subparsers.add_parser("add", help="Add a new task")
+    add_parser.add_argument("title", help="Task title")
+
+    subparsers.add_parser("list", help="List tasks")
+
+    done_parser = subparsers.add_parser("done", help="Mark task as completed")
+    done_parser.add_argument("id", type=int, help="Task id")
+
+    delete_parser = subparsers.add_parser("delete", help="Delete a task")
+    delete_parser.add_argument("id", type=int, help="Task id")
+
+    return parser
+
+
+def main() -> None:
+    parser = _build_parser()
+    args = parser.parse_args()
+
+    tracker = TaskTracker(Path(args.db))
+
+    if args.command == "add":
+        task = tracker.add_task(args.title)
+        print(f"Added task #{task.id}: {task.title}")
+    elif args.command == "list":
+        tasks = tracker.list_tasks()
+        if not tasks:
+            print("No tasks yet.")
+            return
+
+        for task in tasks:
+            status = "✅" if task.done else "⬜"
+            print(f"{status} [{task.id}] {task.title}")
+    elif args.command == "done":
+        task = tracker.complete_task(args.id)
+        print(f"Completed task #{task.id}: {task.title}")
+    elif args.command == "delete":
+        tracker.delete_task(args.id)
+        print(f"Deleted task #{args.id}")
+
+
+if __name__ == "__main__":
+    main()

src/tracker.py

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+from __future__ import annotations
+
+from dataclasses import asdict, dataclass
+from pathlib import Path
+import json
+
+
+@dataclass
+class Task:
+    id: int
+    title: str
+    done: bool = False
+
+
+class TaskTracker:
+    def __init__(self, storage_path: Path) -> None:
+        self.storage_path = storage_path
+        self.tasks: list[Task] = []
+        self._load()
+
+    def _load(self) -> None:
+        if not self.storage_path.exists():
+            self.tasks = []
+            return
+
+        with self.storage_path.open("r", encoding="utf-8") as f:
+            payload = json.load(f)
+
+        self.tasks = [Task(**item) for item in payload]
+
+    def _save(self) -> None:
+        self.storage_path.parent.mkdir(parents=True, exist_ok=True)
+        with self.storage_path.open("w", encoding="utf-8") as f:
+            json.dump([asdict(task) for task in self.tasks], f, indent=2)
+
+    def add_task(self, title: str) -> Task:
+        next_id = 1 if not self.tasks else max(task.id for task in self.tasks) + 1
+        task = Task(id=next_id, title=title.strip(), done=False)
+        if not task.title:
+            raise ValueError("Task title cannot be empty.")
+        self.tasks.append(task)
+        self._save()
+        return task
+
+    def list_tasks(self) -> list[Task]:
+        return self.tasks
+
+    def complete_task(self, task_id: int) -> Task:
+        task = self._find(task_id)
+        task.done = True
+        self._save()
+        return task
+
+    def delete_task(self, task_id: int) -> None:
+        task = self._find(task_id)
+        self.tasks.remove(task)
+        self._save()
+
+    def _find(self, task_id: int) -> Task:
+        for task in self.tasks:
+            if task.id == task_id:
+                return task
+        raise ValueError(f"Task with id={task_id} was not found.")

tests/test_tracker.py

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+from pathlib import Path
+
+import pytest
+
+from src.tracker import TaskTracker
+
+
+def test_add_and_list_tasks(tmp_path: Path) -> None:
+    tracker = TaskTracker(tmp_path / "tasks.json")
+    tracker.add_task("Write code")
+    tracker.add_task("Build solution")
+
+    tasks = tracker.list_tasks()
+    assert [t.title for t in tasks] == ["Write code", "Build solution"]
+    assert [t.id for t in tasks] == [1, 2]
+
+
+def test_complete_and_delete_task(tmp_path: Path) -> None:
+    tracker = TaskTracker(tmp_path / "tasks.json")
+    tracker.add_task("Task A")
+    tracker.complete_task(1)
+    assert tracker.list_tasks()[0].done is True
+
+    tracker.delete_task(1)
+    assert tracker.list_tasks() == []
+
+
+def test_raises_for_invalid_task(tmp_path: Path) -> None:
+    tracker = TaskTracker(tmp_path / "tasks.json")
+    with pytest.raises(ValueError):
+        tracker.complete_task(9)
+
+
+def test_rejects_blank_title(tmp_path: Path) -> None:
+    tracker = TaskTracker(tmp_path / "tasks.json")
+    with pytest.raises(ValueError):
+        tracker.add_task("   ")