Module development and code questions

Hi,
in a custom module (on Drupal7) I'm using an hook_menu that authenticates the user using the function:

$form_state['uid'] = $uid; 
user_login_submit(array(), $form_state); 

If the function is successful then the user is logged into the site.

When the user logs in this way, does the user session expire after a certain period?
Is there a way to change this "expiration time"?

Thank you very much

Claudio

Hi, i am trying to send a mail programmatically. While the mail should be sent, i get the following error from SMTP authentication module (which is setup correctly):

Error sending e-mail from example@gmail.com to example@gmail.com: Message body empty

The hook_module code:

This is really about Layout Builder and layouts that are defined by a module. In this case I'm using Layout Discovery to make this example simple.

So I am building a page using Layout Builder and I have selected a layout (provided by the Layout Discovery module) for a section. Now I'd like to add a field to the layouts configuration form (the form where I can select column widths and set administrative title). Maybe I'd like to add something like a background color picker or a text field for an extra class or whatever. 

Hi there,

I am new to drupal module development.
Please forgive me if the question is too simple.

This question is two fold:
First about strategy: am I going in the right direction?
Second about how to do it... 

I am new to drupal 8 php unit test. I have written a custom service that will take user id and gives an array of user details. I have tried to unit test this function but getting error on $user->get() function.

Here is my module/custom/common/src/CommonService.php