anchor.diff:  include::{testDir}/example/TestingAStackDemo.java[tags=user_guide]
   ----
   
  -NOTE: _Only non-static nested classes_ (i.e. _inner classes_) can serve as
  -`@Nested` tests. Nesting can be arbitrarily deep, and those inner classes are considered
  -to be full members of the test class family with one exception: `@BeforeAll` and
  -`@AfterAll` do not work, because Java does not allow `static` members in inner classes.
  +NOTE: _Only non-static nested classes_ (i.e. _inner classes_) can serve as `@Nested` test
  +classes. Nesting can be arbitrarily deep, and those inner classes are considered to be
  +full members of the test class family with one exception: `@BeforeAll` and `@AfterAll`
  +methods do not work _by default_. The reason is that Java does not allow `static` members
  +in inner classes. However, this restriction can be circumvented by annotating a `@Nested`
  +test class with `@TestInstance(Lifecycle.PER_CLASS)` (see
  +<<writing-tests-test-instance-lifecycle>>).
   
   [[writing-tests-dependency-injection]]
   === Dependency Injection for Constructors and Methods
  
positive.code: ----
  
  `@ExtendWith` and `@Tag` can be declared on a test interface so that classes that
  implement it automatically inherit its tags and extensions. See
  <<extensions-lifecycle-callbacks-before-after-execution>> for the source code of the
  <<extensions-lifecycle-callbacks-timing-extension, TimingExtension>>.
  
  
negative.code: [[writing-tests-test-interfaces-and-default-methods]]
  === Test Interfaces and Default Methods
  
  JUnit Jupiter allows `@Test`, `@RepeatedTest`, `@ParameterizedTest`, `@TestFactory`,
  `@TestTemplate`, `@BeforeEach`, and `@AfterEach` to be declared on interface `default`
  methods. `@BeforeAll` and `@AfterAll` can either be declared on `static` methods in a
  test interface or on interface `default` methods _if_ the concrete test class is
  annotated with `@TestInstance(Lifecycle.PER_CLASS)` (see
  <<writing-tests-test-instance-lifecycle>>). Here are some examples.
  
  [source,java]
  ----
  