Annotation Interface TestFactory

@TestFactory is used to signal that the annotated method is a test factory method.

In contrast to @Test methods, a test factory is not itself a test case but rather a factory for test cases.

@TestFactory methods must not be private or static and must return a Stream, Collection, Iterable, Iterator, or array of DynamicNode instances. Supported subclasses of DynamicNode include DynamicContainer and DynamicTest. Dynamic tests will be executed lazily, enabling dynamic and even non-deterministic generation of test cases.

Any Stream returned by a @TestFactory will be properly closed by calling stream.close(), making it safe to use a resource such as Files.lines() as the initial source of the stream.

@TestFactory methods may optionally declare parameters to be resolved by ParameterResolvers.

Test Execution Order

By default, test methods will be ordered using an algorithm that is deterministic but intentionally nonobvious. This ensures that subsequent runs of a test suite execute test methods in the same order, thereby allowing for repeatable builds. In this context, a test method is any instance method that is directly annotated or meta-annotated with @Test, @RepeatedTest, @ParameterizedTest, @TestFactory, or @TestTemplate.

Although true unit tests typically should not rely on the order in which they are executed, there are times when it is necessary to enforce a specific test method execution order — for example, when writing integration tests or functional tests where the sequence of the tests is important, especially in conjunction with @TestInstance(Lifecycle.PER_CLASS).

To control the order in which test methods are executed, annotate your test class or test interface with @TestMethodOrder and specify the desired MethodOrderer implementation.

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