gradle-master/subprojects/testing-jvm-infrastructure/src/main/java/org/gradle/api/internal/tasks/testing/junit/AllExceptIgnoredTestRunnerBuilder.java
/*
 * Copyright 2022 the original author or authors.
 *
 * 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.gradle.api.internal.tasks.testing.junit;

import org.gradle.internal.Cast;
import org.junit.internal.builders.AllDefaultPossibilitiesBuilder;
import org.junit.internal.builders.IgnoredBuilder;
import org.junit.internal.builders.JUnit4Builder;
import org.junit.runner.Runner;
import org.junit.runners.BlockJUnit4ClassRunner;
import org.junit.runners.model.RunnerBuilder;
import org.slf4j.LoggerFactory;

import java.lang.reflect.Constructor;

public class AllExceptIgnoredTestRunnerBuilder extends AllDefaultPossibilitiesBuilder {

    @SuppressWarnings("deprecation")
    public AllExceptIgnoredTestRunnerBuilder() {
        super(true);
    }

    @Override
    protected IgnoredBuilder ignoredBuilder() {
        return new IgnoredIgnoredBuilder();
    }

    @Override
    protected JUnit4Builder junit4Builder() {
        return new FallbackJUnit4Builder();
    }

    /**
     * Handles a weird case when there are duplicate JUint 4 jars on the classpath with differing
     * versions. Specifically, when one version is below 4.4 and one is above. This case can occur
     * when a user declares a JUnit dependency on the test classpath while Gradle also loads
     * JUnit as a test framework implementation dependency. Note that JUnit4Builder extends
     * {@link RunnerBuilder}, a class which was introduced in 4.5.
     */
    private static class FallbackJUnit4Builder extends JUnit4Builder {
        @Override
        public Runner runnerForClass(Class<?> testClass) throws Throwable {
            try {
                return new BlockJUnit4ClassRunner(testClass);
            } catch (Throwable t) {
                //failed to instantiate BlockJUnitRunner. try deprecated JUnitRunner (for JUnit < 4.5)
                try {
                    Class<Runner> runnerClass = Cast.uncheckedNonnullCast(Thread.currentThread().getContextClassLoader().loadClass("org.junit.internal.runners.JUnit4ClassRunner"));
                    final Constructor<Runner> constructor = runnerClass.getConstructor(Class.class);
                    return constructor.newInstance(testClass);
                } catch (Throwable e) {
                    LoggerFactory.getLogger(getClass()).warn("Unable to load JUnit4 runner to calculate Ignored test cases", e);
                }
            }
            return null;
        }
    }

    private static class IgnoredIgnoredBuilder extends IgnoredBuilder {
        @Override
        public Runner runnerForClass(Class<?> testClass) {
            return null;
        }
    }
}
