Assignment solution fixed

BUG_REPORT.md

@@ -0,0 +1,42 @@
+# Bug Report
+
+## Bug 1: Complete Task silently resets priority to 'medium'
+
+**Title**: `completeTask` changes task priority to 'medium' regardless of its original priority.
+**Expected behavior**: When marking a task as done, its `priority` should remain unchanged from what the user previously set.
+**Actual behavior**: The `priority` field is overwritten with `'medium'`.
+**Steps to reproduce**:
+1. Create a task with priority `'high'`.
+2. Call `PATCH /tasks/:id/complete` on that task.
+3. Observe the returned task data has `priority: 'medium'`.
+**Root cause**: In `src/services/taskService.js`, the `completeTask` function explicitly sets `priority: 'medium'` when creating the updated task object.
+**Suggested fix**: Remove `priority: 'medium'` from the `updated` object construction in `completeTask`.
+
+---
+
+## Bug 2: Get Tasks by Status uses partial matching
+
+**Title**: Unintended partial matching when filtering tasks by status.
+**Expected behavior**: Querying `/tasks?status=in_progress` should only return tasks with an exact match for the status `in_progress`.
+**Actual behavior**: The filter uses `.includes()`, allowing partial string matching. Querying `status=progress` will match `in_progress`, which is undocumented and can cause issues if statuses have overlapping names.
+**Steps to reproduce**:
+1. Create a task with status `in_progress`.
+2. Send a `GET /tasks?status=progress`.
+3. The task is returned, although `progress` is not a valid status name and should return empty or error.
+**Root cause**: In `src/services/taskService.js`, `getByStatus` filters using `t.status.includes(status)` instead of strict equality `===`.
+**Suggested fix**: Change `t.status.includes(status)` to `t.status === status`.
+
+---
+
+## Bug 3: Incorrect pagination math ignores 1-based indexing
+
+**Title**: Pagination skips the first page data because the offset calculation interprets page 1 as page 2.
+**Expected behavior**: `GET /tasks?page=1&limit=10` should return the first 10 tasks (offset 0).
+**Actual behavior**: It returns tasks 11-20 (offset 10), effectively skipping the first page.
+**Steps to reproduce**:
+1. Create 3 tasks (T1, T2, T3).
+2. Request `GET /tasks?page=1&limit=2`.
+3. Only T3 is returned. T1 and T2 are entirely skipped.
+**Root cause**: In `src/services/taskService.js`, `getPaginated` calculates `offset = page * limit`. Since the route sets `page` to default to `1`, `offset` starts at `limit` (e.g., 10), which skips the 0-offset data.
+**Suggested fix**: Change the calculation to `const offset = (page - 1) * Math.max(limit, 1);` but since the service should probably support zero or 1 based consistently, we adjust `offset = (page - 1) * limit;` or fix it in the route. 
+We'll update `getPaginated` to accept `page=1` as the first page and use `offset = (page - 1) * limit`.

CHECKLIST.md

@@ -0,0 +1,14 @@
+# Final Project Checklist
+
+- [x] **Step 1:** Read and understand the existing code (Project structure, endpoints, logic).
+- [x] **Step 2:** Ensure server runs successfully (`npm install`, `npm start` working properly).
+- [x] **Step 3:** Create testing structure (`tests/unit`, `tests/integration` created; Jest config verified).
+- [x] **Step 4:** Write Unit Tests (`taskService.test.js` covers `create`, `getAll`, `update`, `remove`, `completeTask`, `getPaginated`, `getByStatus`, `getStats` + Assign task).
+- [x] **Step 5:** Write Integration Tests (`tasks.test.js` covering standard API endpoints + validations + edge cases).
+- [x] **Step 6:** Achieve > 80% Test Coverage (Currently at **92.95%** Lines).
+- [x] **Step 7:** Write a professional Bug Report (`BUG_REPORT.md` details 3 separate bugs caught by the tests).
+- [x] **Step 8:** Fix a bug (All 3 known bugs were fixed to improve system stability).
+- [x] **Step 9:** Add new feature (`PATCH /tasks/:id/assign` implemented with logic, proper validation, and error handling).
+- [x] **Step 10:** Write tests for the new feature (Added unit and integration coverage for valid assign, missing assignee, not found errors, reassignments).
+- [x] **Step 11:** Final validation check (All tests pass consistently, server operates perfectly).
+- [x] **Step 12:** Prepare Submission (Generated `BUG_REPORT.md`, `COVERAGE_SUMMARY.md`, `CHECKLIST.md`, and `REFLECTION.md`).

COVERAGE_SUMMARY.md

@@ -0,0 +1,14 @@
+# Coverage Summary
+
+| File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s |
+|------|---------|----------|---------|---------|-------------------|
+| **All files** | **93.58** | **82.55** | **93.33** | **92.95** | |
+| src/app.js | 69.23 | 75 | 0 | 69.23 | 10-11, 17-18 |
+| src/routes/tasks.js | 100 | 91.66 | 100 | 100 | 20-21 |
+| src/services/taskService.js | 100 | 94.73 | 100 | 100 | 23 |
+| src/utils/validators.js | 77.77 | 71.79 | 100 | 77.77 | 9,12,15,22,28,31 |
+
+**Analysis**:
+The overall project coverage stands comfortably at **92.95%**, well above the 80% requirement.
+Major logic in `routes` and `services` shows 100% statement and lines coverage.
+The uncovered branches mostly relate to error handling block (lines 10-11 in app.js where express sets the default error handler), main execution (lines 17-18 in app.js), edge validation errors that were omitted to not bloat the simple API tests, and fallback default values.

REFLECTION.md

@@ -0,0 +1,15 @@
+# Reflection
+
+### What would you test next?
+If I were to expand the testing suite further:
+1. **Mocking External Dependencies:** For a real application, I'd integrate a SQLite or PostgreSQL testing database or mock out the data persistence layer using a proper mocking library.
+2. **Stress/Load Testing:** Introduce a tool like Artillery or K6 to test API stability under a high concurrent load.
+3. **Validation logic specifics:** I would add further test scenarios in validation to guarantee dates follow strict schema parameters for time zones.
+
+### What surprised you?
+It was surprising/intriguing to see a very subtle bug implemented into `taskService.getPaginated`. Pagination bugs involving $1$-based arrays versus $0$-based bounds (`offset = page * limit`) trick developers almost constantly! Also, seeing `.includes()` for an exact enumeration match showed why unit tests shouldn't assume the implementation acts accurately to expectations without checking edge cases specifically (like `progress` vs `in_progress`).
+
+### Questions before production release?
+1. **Data Persistence:** Before production, should we connect this to an actual database (e.g. Postgres or MongoDB)? The `in-memory` array isn't durable over restarts.
+2. **Authentication/Authorization:** Who can use the `/assign` or `/complete` routes? Is there an expected security middleware implementation?
+3. **Concurrency:** Are there scenarios where a race condition on `tasks.findIndex` + array mutation can leave state inconsistent?

task-api/src/routes/tasks.js

@@ -1,7 +1,7 @@
 const express = require('express');
 const router = express.Router();
 const taskService = require('../services/taskService');
-const { validateCreateTask, validateUpdateTask } = require('../utils/validators');
+const { validateCreateTask, validateUpdateTask, validateAssignTask } = require('../utils/validators');
 
 router.get('/stats', (req, res) => {
   const stats = taskService.getStats();
@@ -69,4 +69,18 @@ router.patch('/:id/complete', (req, res) => {
   res.json(task);
 });
 
+router.patch('/:id/assign', (req, res) => {
+  const error = validateAssignTask(req.body);
+  if (error) {
+    return res.status(400).json({ error });
+  }
+
+  const task = taskService.assignTask(req.params.id, req.body.assignee);
+  if (!task) {
+    return res.status(404).json({ error: 'Task not found' });
+  }
+
+  res.json(task);
+});
+
 module.exports = router;

task-api/src/services/taskService.js

@@ -6,10 +6,11 @@ const getAll = () => [...tasks];
 
 const findById = (id) => tasks.find((t) => t.id === id);
 
-const getByStatus = (status) => tasks.filter((t) => t.status.includes(status));
+const getByStatus = (status) => tasks.filter((t) => t.status === status);
 
 const getPaginated = (page, limit) => {
-  const offset = page * limit;
+  const pageIndex = Math.max(0, page - 1);
+  const offset = pageIndex * limit;
   return tasks.slice(offset, offset + limit);
 };
 
@@ -66,7 +67,6 @@ const completeTask = (id) => {
 
   const updated = {
     ...task,
-    priority: 'medium',
     status: 'done',
     completedAt: new Date().toISOString(),
   };
@@ -76,6 +76,20 @@ const completeTask = (id) => {
   return updated;
 };
 
+const assignTask = (id, assignee) => {
+  const task = findById(id);
+  if (!task) return null;
+
+  const updated = {
+    ...task,
+    assignee,
+  };
+
+  const index = tasks.findIndex((t) => t.id === id);
+  tasks[index] = updated;
+  return updated;
+};
+
 const _reset = () => {
   tasks = [];
 };
@@ -90,5 +104,6 @@ module.exports = {
   update,
   remove,
   completeTask,
+  assignTask,
   _reset,
 };

task-api/src/utils/validators.js

@@ -33,4 +33,11 @@ const validateUpdateTask = (body) => {
   return null;
 };
 
-module.exports = { validateCreateTask, validateUpdateTask };
+const validateAssignTask = (body) => {
+  if (!body.assignee || typeof body.assignee !== 'string' || body.assignee.trim() === '') {
+    return 'assignee is required and must be a non-empty string';
+  }
+  return null;
+};
+
+module.exports = { validateCreateTask, validateUpdateTask, validateAssignTask };

task-api/tests/integration/tasks.test.js

@@ -0,0 +1,195 @@
+const request = require('supertest');
+const app = require('../../src/app');
+const taskService = require('../../src/services/taskService');
+
+describe('Tasks API Integration Tests', () => {
+  beforeEach(() => {
+    // Reset data before each test to ensure test isolation
+    taskService._reset();
+  });
+
+  describe('GET /tasks', () => {
+    it('should return 200 and an empty array initially', async () => {
+      const res = await request(app).get('/tasks');
+      expect(res.status).toBe(200);
+      expect(res.body).toEqual([]);
+    });
+
+    it('should return 200 and an array of tasks when data exists', async () => {
+      taskService.create({ title: 'Task 1' });
+      const res = await request(app).get('/tasks');
+      expect(res.status).toBe(200);
+      expect(res.body.length).toBe(1);
+      expect(res.body[0].title).toBe('Task 1');
+    });
+
+    it('should filter tasks by status with GET /tasks?status=todo', async () => {
+      taskService.create({ title: 'T1', status: 'todo' });
+      taskService.create({ title: 'T2', status: 'done' });
+
+      const res = await request(app).get('/tasks?status=todo');
+      expect(res.status).toBe(200);
+      expect(res.body.length).toBe(1);
+      expect(res.body[0].status).toBe('todo');
+    });
+
+    it('should paginate tasks with GET /tasks?page=1&limit=1', async () => {
+      taskService.create({ title: 'T1' });
+      taskService.create({ title: 'T2' });
+
+      // Correct expectation: page=1 should return the first item T1
+      const res = await request(app).get('/tasks?page=1&limit=1');
+      expect(res.status).toBe(200);
+      expect(res.body.length).toBe(1);
+      expect(res.body[0].title).toBe('T1');
+    });
+  });
+
+  describe('GET /tasks/stats', () => {
+    it('should return statistics of tasks', async () => {
+      taskService.create({ title: 'T1', status: 'todo' });
+      taskService.create({ title: 'T2', status: 'done' });
+
+      const res = await request(app).get('/tasks/stats');
+      expect(res.status).toBe(200);
+      expect(res.body).toMatchObject({
+        todo: 1,
+        in_progress: 0,
+        done: 1,
+        overdue: 0
+      });
+    });
+  });
+
+  describe('POST /tasks', () => {
+    it('should create a new task successfully', async () => {
+      const res = await request(app)
+        .post('/tasks')
+        .send({ title: 'New API Task' });
+
+      expect(res.status).toBe(201);
+      expect(res.body.title).toBe('New API Task');
+      expect(res.body.id).toBeDefined();
+    });
+
+    it('should fail with 400 when validation fails (missing title)', async () => {
+      const res = await request(app)
+        .post('/tasks')
+        .send({ description: 'No title' });
+
+      expect(res.status).toBe(400);
+      expect(res.body.error).toBeDefined();
+    });
+  });
+
+  describe('PUT /tasks/:id', () => {
+    it('should update an existing task successfully', async () => {
+      const task = taskService.create({ title: 'Initial Title' });
+      const res = await request(app)
+        .put(`/tasks/${task.id}`)
+        .send({ title: 'Updated Title', status: 'in_progress' });
+
+      expect(res.status).toBe(200);
+      expect(res.body.title).toBe('Updated Title');
+      expect(res.body.status).toBe('in_progress');
+    });
+
+    it('should fail with 400 on validation error', async () => {
+      const task = taskService.create({ title: 'Initial Title' });
+      const res = await request(app)
+        .put(`/tasks/${task.id}`)
+        .send({ status: 'invalid_status' });
+
+      expect(res.status).toBe(400);
+      expect(res.body.error).toContain('status must be one of');
+    });
+
+    it('should return 404 when updating non-existent task', async () => {
+      const res = await request(app)
+        .put('/tasks/invalid-id')
+        .send({ title: 'Updated Title' });
+
+      expect(res.status).toBe(404);
+      expect(res.body.error).toBe('Task not found');
+    });
+  });
+
+  describe('DELETE /tasks/:id', () => {
+    it('should successfully delete an existing task', async () => {
+      const task = taskService.create({ title: 'To Delete' });
+      const res = await request(app).delete(`/tasks/${task.id}`);
+
+      expect(res.status).toBe(204);
+      // Verify deletion
+      expect(taskService.findById(task.id)).toBeUndefined();
+    });
+
+    it('should return 404 when deleting a non-existent task', async () => {
+      const res = await request(app).delete('/tasks/invalid-id');
+      expect(res.status).toBe(404);
+      expect(res.body.error).toBe('Task not found');
+    });
+  });
+
+  describe('PATCH /tasks/:id/complete', () => {
+    it('should mark a task as complete successfully', async () => {
+      const task = taskService.create({ title: 'Complete Me' });
+      const res = await request(app).patch(`/tasks/${task.id}/complete`);
+
+      expect(res.status).toBe(200);
+      expect(res.body.status).toBe('done');
+      expect(res.body.completedAt).not.toBeNull();
+    });
+
+    it('should return 404 when completing a non-existent task', async () => {
+      const res = await request(app).patch('/tasks/invalid-id/complete');
+      expect(res.status).toBe(404);
+      expect(res.body.error).toBe('Task not found');
+    });
+  });
+
+  describe('PATCH /tasks/:id/assign', () => {
+    it('should assign a task successfully', async () => {
+      const task = taskService.create({ title: 'Assign Me' });
+      const res = await request(app)
+        .patch(`/tasks/${task.id}/assign`)
+        .send({ assignee: 'Jane Smith' });
+
+      expect(res.status).toBe(200);
+      expect(res.body.assignee).toBe('Jane Smith');
+    });
+
+    it('should return 404 when assigning a non-existent task', async () => {
+      const res = await request(app)
+        .patch('/tasks/invalid-id/assign')
+        .send({ assignee: 'Jane Smith' });
+      expect(res.status).toBe(404);
+      expect(res.body.error).toBe('Task not found');
+    });
+
+    it('should return 400 when assignee is empty or missing', async () => {
+      const task = taskService.create({ title: 'Assign Me' });
+      const res1 = await request(app)
+        .patch(`/tasks/${task.id}/assign`)
+        .send({ assignee: '' });
+      expect(res1.status).toBe(400);
+
+      const res2 = await request(app)
+        .patch(`/tasks/${task.id}/assign`)
+        .send({});
+      expect(res2.status).toBe(400);
+    });
+
+    it('should successfully reassign an existing task', async () => {
+      const task = taskService.create({ title: 'Assign Me' });
+      taskService.assignTask(task.id, 'Original Assignee');
+
+      const res = await request(app)
+        .patch(`/tasks/${task.id}/assign`)
+        .send({ assignee: 'New Assignee' });
+
+      expect(res.status).toBe(200);
+      expect(res.body.assignee).toBe('New Assignee');
+    });
+  });
+});