require rails_helper instead of spec_helper
Guard: run all tests after pass
6.5 Testing respond_to :name and :email
### 6.2.2 Validate presence
### 6.2.3. Length validation
### 6.2.4 email format validation
### 6.2.5 Uniqueness validation
fix a bug in uniqueness test and pretty format model code
6.19 Enforce uniqueness using DB index
6.20 Further ensure uniqueness by downcasing email
## 6.3 Adding a secure password

- require password
- require password confirmation
- store **hashed** password
- authenticate user
6.21 Add gem bcrypt-ruby
Add User.password_digest to store hashed password