What does the following sentence mean Tests can potentiate effectiveness of subsequent study opportunities even under conditions that insure learners will be correct on test.?

This sentence is indicating that tests can enhance the effectiveness of subsequent study opportunities even in situations where learners are guaranteed to be correct on the test. This means that the act of taking a test can help learners to retain information more effectively than simply studying without taking a test, even if the learners are already sure of the correct answers before the test.