🧮 4. Built-in Validators

All built-in validators call AssertString first — passing a non-string throws before any rule runs.

isUsernameValid(entry: string)

Letters, hyphens, spaces only — length 5-35.

isUsernameValid('JohnDoe')  // ✅ { status: true,  error: null }
isUsernameValid('F!')        // ❌ { status: false, error: 'Username must contain only letters' }
isUsernameValid(42 as any)  // 🛡️ throws ArgumentTypeError

isEmailValid(entry: string)

Matches StrictEmail pattern — format xyz@domain.tld.

isEmailValid('test@example.com') // ✅ { status: true,  error: null }
isEmailValid('test@com')         // ❌ { status: false, error: 'Invalid Email address' }

isPhoneNumberValid(entry: string)

Digits only (no +), length 3-12.

isPhoneNumberValid('237653793493')  // ✅ { status: true,  error: null }
isPhoneNumberValid('+237653793493') // ❌ { status: false, error: 'Phone number must contain only digits' }

isPasswordValid(entry: string)

Min 8 chars, uppercase, lowercase, digit, special char (?@!#$%&*).

isPasswordValid('Abcdef1!')  // ✅ { status: true,  error: null }
isPasswordValid('abcdef1!')  // ❌ { status: false, error: 'Password must contain atleast an uppercase letter' }

isRequired(entry: string)

String must be non-empty after trimming.

isRequired('Some value') // ✅ { status: true,  error: null }
isRequired('')           // ❌ { status: false, error: 'This field is required' }

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