Common Notes

• Test classes and methods need not to be public but can be package private.
  • Reduces unwanted visibility of classes and methods, useful e.g. in Eclipse.
• Can have nested test classes.
  • Helps to structure test classes.

Grouping Tests

Grouping of test classes:

• Per class (http://xunitpatterns.com/Testcase%20Class%20per%20Class.html)
  • Most common approach
  • Can lead to large test classes
  • Test class naming: + "Test"
• Per feature (e.g method) (http://xunitpatterns.com/Testcase%20Class%20per%20Feature.html)
  • Can lead to many fine grained test classes
  • Example test class naming for Test class for method: +"_" + +"_" + "Test" (The "_" separates the class and method part of the name. Without a delimiter it will be unclear, what is part of the class name and what is part of the method name)
• Per fixture setup (http://xunitpatterns.com/Testcase%20Class%20per%20Fixture.html)

JUnit Jupiter @Nested annotation

See https://junit.org/junit5/docs/current/api/org/junit/jupiter/api/Nested.html

@Nested is used to signal that the annotated class is a nested, non-static test class (i.e., an inner class) that can share setup and state with an instance of its enclosing class. The enclosing class may be a top-level test class or another @Nested test class, and nesting can be arbitrarily deep.

• Group test methods for feature / methods
• Can share state and initialization with outer class
• Grouping of test classes can be
  • Test class per class
  • Nested test class per method / feature

A nice example is https://github.com/apache/commons-lang/blob/master/src/test/java/org/apache/commons/lang3/ValidateTest.java

Static Nested Test Classes

See discussion https://github.com/junit-team/junit5/issues/69

• Treated like top-level class.

Assertions

See https://junit.org/junit5/docs/current/user-guide/#writing-tests-assertions

• Methods of class org.junit.jupiter.api.Assertions

Can also use Hamcrest http://hamcrest.org/JavaHamcrest/index with the org.hamcrest.MatcherAssert.assertThat(...) methods. Background: https://objectpartners.com/2013/09/18/the-benefits-of-using-assertthat-over-other-assert-methods-in-unit-tests/

References

• https://junit.org/junit5/
• http://xunitpatterns.com
• https://github.com/jupiter-tools