Doing a SQL Server Healthcheck via PowerShell

PowerShell is an ideal tool for doing health-checks of a collection of SQL Server instances, and there are several examples around, but few acknowledge the fact that individual DBAs have their own priorities for tests, and need something easily changed to suit circumstances. Omid Afzalalghom's Healthcheck allows tests to be SQL or PowerShell and requires only adding, altering or deleting files in directories.