clean test schemaless
unmmaped returns [] on :list non-existing values- nil otherwise
cleaned after/before suite in index test
predicate list is cached in paging object - used for :unmapped retrieval
test for predicate reuse in :unmmaped attr retrieval and pagination.
test where - aggregates also return 0ed value instances
test where - include can only be called in Where objects not resource directly
test model complex - [] vs nil for :list attributes