feat: add JSON output format

README.md

@@ -18,11 +18,23 @@ python task.py --help
 # Add a task
 python task.py add "Buy groceries"
 
+# Add a task and print machine-readable JSON
+python task.py add "Buy groceries" --json
+# {"task": {"id": 1, "description": "Buy groceries", "done": false}, "message": "Added task 1"}
+
 # List tasks
 python task.py list
 
+# List tasks as JSON
+python task.py list --json
+# {"tasks": [{"id": 1, "description": "Buy groceries", "done": false}], "count": 1}
+
 # Complete a task
 python task.py done 1
+
+# Complete a task and print JSON
+python task.py done 1 --json
+# {"task": {"id": 1, "description": "Buy groceries", "done": true}, "message": "Marked task 1 as done"}
 ```
 
 ## Testing

commands/add.py

@@ -19,7 +19,7 @@ def validate_description(description):
     return description.strip()
 
 
-def add_task(description):
+def add_task(description, json_output=False):
     """Add a new task."""
     description = validate_description(description)
 
@@ -31,7 +31,12 @@ def add_task(description):
         tasks = json.loads(tasks_file.read_text())
 
     task_id = len(tasks) + 1
-    tasks.append({"id": task_id, "description": description, "done": False})
+    task = {"id": task_id, "description": description, "done": False}
+    tasks.append(task)
 
     tasks_file.write_text(json.dumps(tasks, indent=2))
-    print(f"Added task {task_id}: {description}")
+
+    if json_output:
+        print(json.dumps({"task": task, "message": f"Added task {task_id}"}))
+    else:
+        print(f"Added task {task_id}: {description}")

commands/done.py

@@ -17,11 +17,14 @@ def validate_task_id(tasks, task_id):
     return task_id
 
 
-def mark_done(task_id):
+def mark_done(task_id, json_output=False):
     """Mark a task as complete."""
     tasks_file = get_tasks_file()
     if not tasks_file.exists():
-        print("No tasks found!")
+        if json_output:
+            print(json.dumps({"task": None, "message": "No tasks found"}))
+        else:
+            print("No tasks found!")
         return
 
     tasks = json.loads(tasks_file.read_text())
@@ -31,7 +34,13 @@ def mark_done(task_id):
         if task["id"] == task_id:
             task["done"] = True
             tasks_file.write_text(json.dumps(tasks, indent=2))
-            print(f"Marked task {task_id} as done: {task['description']}")
+            if json_output:
+                print(json.dumps({"task": task, "message": f"Marked task {task_id} as done"}))
+            else:
+                print(f"Marked task {task_id} as done: {task['description']}")
             return
 
-    print(f"Task {task_id} not found")
+    if json_output:
+        print(json.dumps({"task": None, "message": f"Task {task_id} not found"}))
+    else:
+        print(f"Task {task_id} not found")

commands/list.py

@@ -18,15 +18,17 @@ def validate_task_file():
     return tasks_file
 
 
-def list_tasks():
+def list_tasks(json_output=False):
     """List all tasks."""
-    # NOTE: No --json flag support yet (feature bounty)
     tasks_file = validate_task_file()
     if not tasks_file:
-        print("No tasks yet!")
-        return
+        tasks = []
+    else:
+        tasks = json.loads(tasks_file.read_text())
 
-    tasks = json.loads(tasks_file.read_text())
+    if json_output:
+        print(json.dumps({"tasks": tasks, "count": len(tasks)}))
+        return
 
     if not tasks:
         print("No tasks yet!")

task.py

@@ -2,7 +2,6 @@
 """Simple task manager CLI."""
 
 import argparse
-import sys
 from pathlib import Path
 
 from commands.add import add_task
@@ -25,22 +24,25 @@ def main():
     # Add command
     add_parser = subparsers.add_parser("add", help="Add a new task")
     add_parser.add_argument("description", help="Task description")
+    add_parser.add_argument("--json", action="store_true", help="Output result as JSON")
 
     # List command
     list_parser = subparsers.add_parser("list", help="List all tasks")
+    list_parser.add_argument("--json", action="store_true", help="Output tasks as JSON")
 
     # Done command
     done_parser = subparsers.add_parser("done", help="Mark task as complete")
     done_parser.add_argument("task_id", type=int, help="Task ID to mark done")
+    done_parser.add_argument("--json", action="store_true", help="Output result as JSON")
 
     args = parser.parse_args()
 
     if args.command == "add":
-        add_task(args.description)
+        add_task(args.description, json_output=args.json)
     elif args.command == "list":
-        list_tasks()
+        list_tasks(json_output=args.json)
     elif args.command == "done":
-        mark_done(args.task_id)
+        mark_done(args.task_id, json_output=args.json)
     else:
         parser.print_help()
 

test_task.py

@@ -1,8 +1,11 @@
 """Basic tests for task CLI."""
 
 import json
+import os
+import subprocess
+import sys
+
 import pytest
-from pathlib import Path
 from commands.add import add_task, validate_description
 from commands.done import validate_task_id
 
@@ -28,3 +31,58 @@ def test_validate_task_id():
 
     with pytest.raises(ValueError):
         validate_task_id(tasks, 99)
+
+
+def run_task_cli(tmp_path, *args):
+    """Run the task CLI with an isolated HOME directory."""
+    env = os.environ.copy()
+    env["HOME"] = str(tmp_path)
+    result = subprocess.run(
+        [sys.executable, "task.py", *args],
+        capture_output=True,
+        check=True,
+        env=env,
+        text=True,
+    )
+    return result.stdout.strip()
+
+
+def test_add_json_output(tmp_path):
+    """Add command prints parseable JSON when --json is present."""
+    output = run_task_cli(tmp_path, "add", "Write tests", "--json")
+    payload = json.loads(output)
+
+    assert payload["task"] == {"id": 1, "description": "Write tests", "done": False}
+    assert payload["message"] == "Added task 1"
+
+
+def test_list_json_output(tmp_path):
+    """List command prints all tasks as parseable JSON."""
+    run_task_cli(tmp_path, "add", "First task")
+    run_task_cli(tmp_path, "add", "Second task")
+
+    output = run_task_cli(tmp_path, "list", "--json")
+    payload = json.loads(output)
+
+    assert payload["count"] == 2
+    assert payload["tasks"] == [
+        {"id": 1, "description": "First task", "done": False},
+        {"id": 2, "description": "Second task", "done": False},
+    ]
+
+
+def test_done_json_output(tmp_path):
+    """Done command prints the completed task as parseable JSON."""
+    run_task_cli(tmp_path, "add", "Finish bounty")
+
+    output = run_task_cli(tmp_path, "done", "1", "--json")
+    payload = json.loads(output)
+
+    assert payload["task"] == {"id": 1, "description": "Finish bounty", "done": True}
+    assert payload["message"] == "Marked task 1 as done"
+
+
+def test_list_json_output_when_empty(tmp_path):
+    """List command returns an empty task array as JSON with no task file."""
+    output = run_task_cli(tmp_path, "list", "--json")
+    assert json.loads(output) == {"tasks": [], "count": 0}