Timing-extension to measure test performance. Include before SpringExtension to measure test including instantiation of applicationcontext.

TimingExtension.java

public class TimingExtension implements AfterAllCallback, TestInstancePostProcessor {

    private static final Logger logger = Logger.getLogger(TimingExtension.class.getName());

    private static final String START_TIME = "start time";

    @Override
    public void postProcessTestInstance(Object testInstance, ExtensionContext context) {
        getStore(context).put(START_TIME, System.currentTimeMillis());
    }

    @Override
    public void afterAll(ExtensionContext context) {
        Class<?> testClass = context.getRequiredTestClass();
        long startTime = getStore(context).remove(START_TIME, long.class);
        long duration = System.currentTimeMillis() - startTime;

        logger.info(() -> String.format("%s=%sms.", getClassName(testClass), Duration.ofMillis(duration).toString()));
    }

    private String getClassName(Class<?> testClass) {
        if (testClass.getEnclosingClass() != null) {
            return testClass.getEnclosingClass().getSimpleName() + "#" + testClass.getSimpleName();
        } else {
            return testClass.getSimpleName();
        }
    }

    private Store getStore(ExtensionContext context) {
        return context.getStore(Namespace.create(getClass(), context.getRequiredTestClass()));
    }
}