tdlib
Testing registration with tdlib built custom client
Tdlib is a powerful tool to create custom clients, but trying to test registration for new user is very difficult. After I created an account how can I check if sign-in works? There is the possibility to use a developer mode with a demo backend to simulate registration process?
The authorization process is the same as in all other clients. You will receive updateAuthorizationState if authorization state is changed.
I know, but for testing purposes of registration process (screens and behavior) there is a way to simulate it?
No. But you can use test DC, which has test accounts: https://core.telegram.org/api/auth#test-accounts.