Most of the time you will not need to interact with the classes in Boost.Test because the macro facilities for assertions, test cases and test suites hide all the details of the classes. If you are adapting legacy test code to Boost.Test you may need to interact with these classes in order to leverage existing test code without significant refactoring of the legacy test code.

The predicate_result class is used to combine a boolean result from a predicate with a custom failure message for reporting additional detail in the context of a failed assertion. The test_unit, test_case, test_suite and master_test_suite_t classes provide the interface to test suites and their test cases for the test runner. The test_observer, unit_test_log_t and unit_test_log_formatter classes provide low-level interaction with the test runner log.