Hey all, We're introducing a mess to the codebase. It's a small problem, but several small problems become a big problem and one of my missions is to clean up and improve the codebase.
I recently started seeing lots of pull requests with usage of @TestOnly. Sometimes it's used instead of @VisibleForTesting, while sometimes I see both annotations added to the same method. Before we start using @TestOnly, I think we need some guidelines for when to use @TestOnly versus @VisibleForTesting. Or if we're going to replace @VisibleForTesting with @TestOnly, then we either need a PR for the replacement or, at a minimum, deprecation annotation and javadocs added to VisibleForTesting.java. The annotations appear similar but the javadocs describe slightly different meanings for them... *@VisibleForTesting* was created in Geode several years ago to mean that the method is either only for testing or the visibility of it was widened (example: a private method might be widened to be package-private, protected or public). The method might be used by product code, but it also has widened scope specifically to allow tests to call it. The javadocs say: "Annotates a program element that exists, or is more widely visible than otherwise necessary, only for use in test code. Introduced while mobbing with Michael Feathers. Name and javadoc borrowed from Guava and AssertJ (both are Apache License 2.0)." *@TestOnly* started appearing when we added org.jetbrains.annotations dependency earlier this year. It seems to indicate a method that is ONLY used for tests (never called by product). The javadocs say: "A member or type annotated with TestOnly claims that it should be used from testing code only. Apart from documentation purposes this annotation is intended to be used by static analysis tools to validate against element contract violations. This annotation means that the annotated element exposes internal data and breaks encapsulation of the containing class; the annotation won't prevent its use from production code, developers even won't see warnings if their IDE doesn't support the annotation. It's better to provide proper API which can be used in production as well as in tests." So... when do we use one over the other? I don't think both annotations should be on the same method. Also, some sort of guidelines are needed if we're going to start using @TestOnly.
