@AutoClose is used to indicate that an annotated field will be automatically closed after test execution.

@AutoClose fields may be either static or non-static. If the value of an @AutoClose field is null when it is evaluated the field will be ignored, but a warning message will be logged to inform you.

By default, @AutoClose expects the value of the annotated field to implement a close() method that will be invoked to close the resource. However, developers can customize the name of the close method via the value attribute. For example, @AutoClose("shutdown") instructs JUnit to look for a shutdown() method to close the resource.

@AutoClose may be used as a meta-annotation in order to create a custom composed annotation that inherits the semantics of @AutoClose.

Inheritance

@AutoClose fields are inherited from superclasses. Furthermore, @AutoClose fields from subclasses will be closed before @AutoClose fields in superclasses.

Evaluation Order

When multiple @AutoClose fields exist within a given test class, the order in which the resources are closed depends on an algorithm that is deterministic but intentionally nonobvious. This ensures that subsequent runs of a test suite close resources in the same order, thereby allowing for repeatable builds.

Scope and Lifecycle

The extension that closes @AutoClose fields implements the AfterAllCallback and TestInstancePreDestroyCallback extension APIs. Consequently, a static @AutoClose field will be closed after all tests in the current test class have completed, effectively after @AfterAll methods have executed for the test class. A non-static @AutoClose field will be closed before the current test class instance is destroyed. Specifically, if the test class is configured with @TestInstance(Lifecycle.PER_METHOD) semantics, a non-static @AutoClose field will be closed after the execution of each test method, test factory method, or test template method. However, if the test class is configured with @TestInstance(Lifecycle.PER_CLASS) semantics, a non-static @AutoClose field will not be closed until the current test class instance is no longer needed, which means after @AfterAll methods and after all static @AutoClose fields have been closed.