test(models): add edge case and validation tests for Notification schema

Author: TanmayNelge

models/Notification.empty-fallback.test.ts

@@ -0,0 +1,86 @@
+import { describe, it, expect } from 'vitest';
+import { Notification } from './Notification';
+
+describe('Notification Model - Edge Cases & Empty/Missing Inputs Verification', () => {
+  // 1. Missing required fields (Empty Object)
+  it('throws validation errors when instantiated with completely empty parameters', () => {
+    const notification = new Notification({});
+
+    // validateSync() allows us to check schema rules without needing a real MongoDB connection
+    const err = notification.validateSync();
+
+    expect(err).toBeDefined();
+    expect(err?.errors.username).toBeDefined();
+    expect(err?.errors.username.message).toContain('Path `username` is required');
+
+    expect(err?.errors.email).toBeDefined();
+    expect(err?.errors.email.message).toContain('Path `email` is required');
+  });
+
+  // 2. Missing optional fields (Verify Default Fallbacks)
+  it('applies default fallback configuration values when optional fields are completely missing', () => {
+    const notification = new Notification({
+      username: 'testuser',
+      email: 'test@example.com',
+    });
+
+    const err = notification.validateSync();
+
+    // Should have no validation errors since required fields are present
+    expect(err).toBeUndefined();
+
+    // Verify all the unconfigured object fields safely fell back to schema defaults
+    expect(notification.frequency).toBe('daily');
+    expect(notification.notifyOnCommit).toBe(true);
+    expect(notification.notifyOnStreak).toBe(true);
+    expect(notification.notifyOnMilestone).toBe(true);
+    expect(notification.isActive).toBe(true);
+    expect(notification.createdAt).toBeDefined();
+    expect(notification.updatedAt).toBeDefined();
+  });
+
+  // 3. Empty string/whitespace handling
+  it('fails validation safely if required strings contain only empty spaces', () => {
+    const notification = new Notification({
+      username: '   ', // Schema has `trim: true`, so this reduces to an empty string
+      email: '   ',
+    });
+
+    const err = notification.validateSync();
+
+    expect(err).toBeDefined();
+    // Mongoose recognizes the trimmed empty string as a missing required field
+    expect(err?.errors.username).toBeDefined();
+    expect(err?.errors.email).toBeDefined();
+  });
+
+  // 4. Invalid Enum Inputs (Missing standard layout state)
+  it('rejects invalid inputs for enumerated fields and prevents database corruption', () => {
+    const notification = new Notification({
+      username: 'testuser',
+      email: 'test@example.com',
+      frequency: 'hourly', // Invalid! Valid options are: realtime, daily, weekly
+    });
+
+    const err = notification.validateSync();
+
+    expect(err).toBeDefined();
+    expect(err?.errors.frequency).toBeDefined();
+    expect(err?.errors.frequency.message).toContain('is not a valid enum value');
+  });
+
+  // 5. Type Casting Failures (Hydration/Runtime Error Resilience)
+  it('gracefully handles invalid types by throwing standard cast errors instead of crashing', () => {
+    const notification = new Notification({
+      username: 'testuser',
+      email: 'test@example.com',
+      notifyOnCommit: 'not-a-boolean-value', // Injecting a raw string into a boolean field
+    });
+
+    const err = notification.validateSync();
+
+    expect(err).toBeDefined();
+    expect(err?.errors.notifyOnCommit).toBeDefined();
+    expect(err?.errors.notifyOnCommit.name).toBe('CastError');
+  });
+});