To define a custom test listener you need to implement the TestListener interface /* * Copyright 2020 webtau maintainers * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.testingisdocumenting.webtau; import org.testingisdocumenting.webtau.reporter.WebTauTest; import java.util.List; /** * Lowest common denominator for Groovy Standalone Tests, JUnit4, JUnit5 */ public interface TestListener { /** * before any test is ran */ default void beforeFirstTest() {} /** * before test code is invoked * @param test test */ default void beforeTestRun(WebTauTest test) {} /** * after test code is invoked * @param test test */ default void afterTestRun(WebTauTest test) {} /** * after all the tests are invoked */ default void afterAllTests() {} /** * after test is ran but before its first statement. * executed code in this listener is considered to be part of a test. * @param test test */ default void beforeFirstTestStatement(WebTauTest test) {} /** * right before test considered to be complete. May not be executed if the test didn't reach the last statement. * executed code in this listener is considered to be part of a test. * @param test test */ default void afterLastTestStatement(WebTauTest test) {} /** * after all the tests are discovered * @param tests stream of discovered tests */ default void afterTestsRegistration(List<WebTauTest> tests) {} }

Once you have an implementation, use the testListeners key in your config file to use it import listeners.MetadataValidationTestListener testListeners = [MetadataValidationTestListener] package listeners import org.testingisdocumenting.webtau.TestListener import org.testingisdocumenting.webtau.reporter.WebTauTest class MetadataValidationTestListener implements TestListener { @Override void afterLastTestStatement(WebTauTest test) { if (!test.isSynthetic() && !test.metadata.has('owner')) { throw new RuntimeException('owner for <' + test.scenario + '> is not set') } } }