Problem/Motivation
Many of the Migrate Kernel tests have a method for asserting an entity and the method exists in both the d6 and d7 version of the test. Instead there should be one assertEntity method that is used by both the d6, d7 and future d8 tests. Note that the methods for an entity type may be different from d6 and d7.
Instead, we should use either a base class or a trait to create a set of assertions for all entities.
This has been on my mind for a while but not a priority. However, larowlan asked about making a base class of trait for asserting node revisions [#3079298]-comment #5 and that drove me to make this issue.
Proposed resolution
Decide if this is worth doing.
Decide if a trait or base class is preferred.
Do the work