Assertions (or asserts) in JUnit are static method calls that you drop into your tests. Each assertion is an opportunity to verify that some condition holds true. If an asserted condition does not hold true, the test stops right there, and JUnit reports a test failure.
(It’s also possible that when JUnit runs your test, an exception is thrown and not caught. In this case, JUnit reports a test error.)
JUnit supports two major assertion styles—classic-style assertions that shipped with the original version of JUnit, and a newer, more expressive style known as Hamcrest (an anagram of the word matchers).
Each of the two assertion styles provides a number of different forms for use in different circumstances. You can mix and ...