For all tests
* use Component::construct instead of main
* use new connection constructors with env argument
* use log instead of printf
For some tests
* replace signal receivers with signal handlers
* replace global static variables with Main class members
* remove unnecessary multithreading
* model test steps as classes that are independent from each other and managed
by Main as constructibles
* use references instead of pointers and exceptions instead of error codes
* use Attached_* helpers intead of doing attach/detach manually
* use helpers like String, Id_space, Registry instead of arrays and lists
* make the run script suitable for automated execution and conclusion
Ref #1987
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082
