java - In JUnit 5, how to run code before all tests

Question

The @BeforeAll annotation marks a method to run before all tests in a class.

http://junit.org/junit5/docs/current/user-guide/#writing-tests-annotations

But is there a way to run some code before all tests, in all classes?

I want to ensure that tests use a certain set of database connections, and the global one-time setup of these connections must occur before running any tests.

Answer 1

This is now possible in JUnit5 by creating a custom Extension, from which you can register a shutdown hook on the root test-context.

Your extension would look like this;

import org.junit.jupiter.api.extension.BeforeAllCallback;
import org.junit.jupiter.api.extension.ExtensionContext;
import static org.junit.jupiter.api.extension.ExtensionContext.Namespace.GLOBAL;

public class YourExtension implements BeforeAllCallback, ExtensionContext.Store.CloseableResource {

    private static boolean started = false;

    @Override
    public void beforeAll(ExtensionContext context) {
        if (!started) {
            started = true;
            // Your "before all tests" startup logic goes here
            // The following line registers a callback hook when the root test context is shut down
            context.getRoot().getStore(GLOBAL).put("any unique name", this);
        }
    }

    @Override
    public void close() {
        // Your "after all tests" logic goes here
    }
}

Then, any tests classes where you need this executed at least once, can be annotated with:

@ExtendWith({YourExtension.class})

When you use this extension on multiple classes, the startup and shutdown logic will only be invoked once.