Add unit tests for AuthHandlers

This commit introduces a set of unit tests for the AuthHandlers in the API. Each test case covers a specific functionality, such as SignUp, SignIn, GetUser, DeleteUser, ChangeUserRole, UpdateUserPassword, UpdateUserEmail, UpdateUserName, and ListUsers. Custom mock client wrappers are used to simulate the behavior of the gRPC service calls, ensuring that the handlers interact correctly with the AuthService. The tests aim to improve the test coverage and validate the correctness of the authentication-related endpoints.

api/handlers/auth.go

@@ -19,7 +19,7 @@ type AuthHandlers interface {
 	UpdateUserPassword(c *fiber.Ctx) error
 	UpdateUserEmail(c *fiber.Ctx) error
 	UpdateUserName(c *fiber.Ctx) error
-	GetUsers(c *fiber.Ctx) error
+	ListUsers(c *fiber.Ctx) error
 }
 
 // authHandlers provides a connection with authentication service over proto buffer.
@@ -193,8 +193,8 @@ func (h *authHandlers) UpdateUserName(c *fiber.Ctx) error {
 	return util.WriteAsJSON(c, http.StatusOK, updatedUser)
 }
 
-// GetUsers lists all users.
-func (h *authHandlers) GetUsers(c *fiber.Ctx) error {
+// ListUsers lists all users.
+func (h *authHandlers) ListUsers(c *fiber.Ctx) error {
 	userId, err := util.GetUserIDFromToken(c)
 	if err != nil {
 		return util.WriteError(c, http.StatusBadRequest, err)