Tests

Document nulls #1967

Job	Run time
Setup & Build Docker Image	5m 40s
Adapter Tests (MySQL)	3m 51s
Adapter Tests (SQLite)	2m 12s
Unit Test	49s
Adapter Tests (SharedTables/MariaDB)	3m 9s
Adapter Tests (Pool)	4m 3s
Adapter Tests (MariaDB)	3m 10s
Adapter Tests (Mirror)	4m 11s
Adapter Tests (SharedTables/Postgres)	2m 45s
Adapter Tests (SharedTables/MySQL)	3m 51s
Adapter Tests (Postgres)	2m 37s
Adapter Tests (SharedTables/SQLite)	2m 4s
	38m 22s

Provide feedback