please explain from the attached code snippet how i can implement testing and produce documentation and verification consideration, the code is from a use case $\frac{?}{{?}^{****}}$

Represents an employee in the HK system.

OCL Constraints:

Non$-$empty username and password.

Implementation of accessInternalData$()$ method.

$*/$

class HKEmployee $\{$

$//$ class implementation

$\}$

$\frac{?}{?}****$

Represents a client in the HK system.

OCL Constraints:

Non$-$empty username and password.

Implementation of accessInternalData$()$ method.

$*/$

class HKClient $\{$

$//$ class implementation

$\}$

$\frac{?}{?}****$

Represents the net portal in the HK system.

OCL Constraints:

Reference to ProjectEmails and ClientInfo.

$*\frac{*}{?}$

class netPortal $\{$

$//$ class implementation

$\}$