Specify a list of resources that are locked by this test.
If multiple tests specify the same resource lock, they are guaranteed not to run concurrently.
FIXTURES_REQUIRED if the resource requires any setup or
RESOURCE_LOCK properties serve
similar purposes, but they are distinct and orthogonal. Resources specified by
RESOURCE_GROUPS do not affect
RESOURCE_LOCK, and vice versa.
RESOURCE_LOCK is a simpler property that is used for locking one
RESOURCE_GROUPS is a more advanced property
that allows multiple tests to simultaneously use multiple resources of the
same type, specifying their requirements in a fine-grained manner.