The structure must be right before the data can be: the tables the design says exist, the columns with the types the design says, the technical columns every table of a layer must carry. The design is a sheet, reality is a catalog view, both are data sources, so the structure is tested with the same five expectations. Obligatory reading before writing a test against INFORMATION_SCHEMA, a catalog, a design spreadsheet or a data dictionary, and before enforcing a naming or layering convention as a test.
