Right now, commons-numbers is using JUnit 4.12, the last stable version of JUnit 4. As far as I am aware, there is no explicit syntax in JUnit 4.12 for testing whether an exception is thrown apart from either using the deprecated class ExpectedException or adding the "expected" parameter to the Test annotation. The problem with the latter approach is that it is impossible to ascertain where exactly in the annotated method the exception is thrown – it could be thrown somewhere unexpected and the test will still pass. Besides, when testing the same exception trigger with multiple different inputs, it is impractical to create a separate method for each test case, which would be necessary with both aforementioned approaches.
This has led to the creation of constructs where the expected exception is swallowed, which has been deemed undesirable <https://issues.apache.org/jira/browse/NUMBERS-99?focusedCommentId=16843419&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-16843419>. Because of this, I propose to add JUnit 5 as a dependency in commons-numbers. JUnit 5 has several "assertThrows" methods that would solve the described dilemma.
