The test catalog contains the collected idioms for testing common coding situations. These can range from simple idioms like "test all String inputs for the zero-length and overflow boundary conditions" to moderately complex data validation tests like "present a non-contiguous subnet-mask to any method expecting an IP / netmask pair", to exceptionally complex exercising of internal use of hash tables, etc.
Where appropriate and possible, the test catalog will contain actual libraries of test code to be inserted into generated tests. When the clue extractor finds "hits" against test catalog entries, it will suggest any relevant test code, which the designer can accept or veto in the test design tool.
The test catalog will also contain descriptions of the testing idiom and testing suggestions, for those cases where canned code is either not appropriate or not possible.