Hello everybody 
TLDR: How to use the DI Container to inject services depending on values which are only known in runtime.
First of all let me swiftly explain what my service does:
I have a service called AlfredFTP which basically lets me check given (S)FTP Login data if they are correct or not.
I separated each check logic into their own connection variants which are
- Plain FTP
- FTP with implicit SSL/TLS
- FTP with explicit SSL/TLS
- SFTP
So in my AlfredFTP base class I basically do
switch( $this->login_data->connection_type_id ) {
case static::CONN_ID_FTP:
$this->check_ftp_data();
break;
case static::CONN_ID_FTP_IMPLICIT:
$this->check_implicit_ftp_data();
break;
case static::CONN_ID_FTP_EXPLICIT:
$this->check_explicit_ftp_data();
break;
case static::CONN_ID_SFTP:
$this->check_sftp_data();
break;
Now in each of those functions I do some think like
$ftp = new FTP( $this->categoryHelper );
$is_valid = $ftp->is_valid( $this->login_data );
if( $is_valid ):
// more logic
endif;
but as you see I “hardcoded” the new FTP( $this->categoryHelper ); part in there.
This is what I want to change to more easily make my service class testable via mocked services in phpunit.
But I just can’t get my head around how I should do that or how I should refactor my service class to make that possible because depending on the value present in $this->login_data->connection_type_id I want to have a object from a different class.
I am sure this is somehow possible so I really would appreciate if someone could enlighten me