Test waits till synchronization is started, then interrupts network connection, wait for a failure event and restore network connection, confirming that after the connection is restored synchronization will proceed.
Network disconnect is introduced by removing default gateway, easily reversible condition.
On my local machine it takes 30 seconds for peers to reconnect after connectivity is restored. As you guess this is not an accident, and there is 30 seconds timeout for dial expiration. This dial expiration is used in p2p.Server to guarantee that peers are not dialed too often.
Additionally I added small script to Makefile to run such tests in docker environment, usage example:
```
make docker-test ARGS="./t/destructive/ -v -network=4"
```
Dmitry Shulyak
Igor Mandrigin
Caner Çıdam
Pedro Pombeiro
Igor Mandrigin
Adam Babik