maven-test-support/src/main/java/org/apache/maven/test/ParameterizedExtension.java

package org.apache.maven.test;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import org.junit.jupiter.api.extension.Extension;
import org.junit.jupiter.api.extension.ExtensionContext;
import org.junit.jupiter.api.extension.TestInstancePostProcessor;
import org.junit.jupiter.api.extension.TestInstantiationException;
import org.junit.jupiter.api.extension.TestTemplateInvocationContext;
import org.junit.jupiter.api.extension.TestTemplateInvocationContextProvider;
import org.junit.jupiter.params.converter.DefaultArgumentConverter;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.platform.commons.util.CollectionUtils;
import org.junit.platform.commons.util.ReflectionUtils;

import static org.junit.jupiter.params.provider.Arguments.arguments;
import static org.junit.platform.commons.util.AnnotationUtils.isAnnotated;

/**
 * ParameterizedExtension
 */
public class ParameterizedExtension implements TestTemplateInvocationContextProvider
{

    @Override
    public boolean supportsTestTemplate( ExtensionContext context )
    {
        return context.getTestMethod()
                .map( m -> isAnnotated( m, Test.class ) )
                .orElse( false );
    }

    @Override
    public Stream<TestTemplateInvocationContext> provideTestTemplateInvocationContexts(
            ExtensionContext extensionContext )
    {
        Class<?> testClass = extensionContext.getRequiredTestClass();
        try
        {
            List<Method> parameters = getParametersMethods( testClass );
            if ( parameters.size() != 1 )
            {
                throw new IllegalStateException(
                        "Class " + testClass.getName() + " should provide a single method annotated with @"
                                                + Parameters.class.getSimpleName() );
            }
            Object params = parameters.iterator().next().invoke( null );
            return CollectionUtils.toStream( params )
                    .map( ParameterizedExtension::toArguments )
                    .map( Arguments::get )
                    .map( ParameterizedTemplate::new );
        }
        catch ( Exception e )
        {
            throw new IllegalStateException( "Unable to generate test templates for class " + testClass.getName(), e );
        }
    }

    private List<Method> getParametersMethods( Class<?> testClass )
    {
        List<Method> parameters = Stream.of( testClass.getDeclaredMethods() )
                .filter( m -> Modifier.isStatic( m.getModifiers() ) )
                .filter( m -> m.getAnnotation( Parameters.class ) != null )
                .collect( Collectors.toList() );
        if ( parameters.isEmpty() && testClass != null )
        {
            return getParametersMethods( testClass.getSuperclass() );
        }
        else
        {
            return parameters;
        }
    }

    private static Arguments toArguments( Object item )
    {
        // Nothing to do except cast.
        if ( item instanceof Arguments )
        {
            return ( Arguments ) item;
        }
        // Pass all multidimensional arrays "as is", in contrast to Object[].
        // See https://github.com/junit-team/junit5/issues/1665
        if ( ReflectionUtils.isMultidimensionalArray( item ) )
        {
            return arguments( item );
        }
        // Special treatment for one-dimensional reference arrays.
        // See https://github.com/junit-team/junit5/issues/1665
        if ( item instanceof Object[] )
        {
            return arguments( ( Object[] ) item );
        }
        // Pass everything else "as is".
        return arguments( item );
    }

    /**
     * ParameterizedTemplate
     */
    public static class ParameterizedTemplate implements TestTemplateInvocationContext
    {

        private final Object[] params;

        public ParameterizedTemplate( Object[] params )
        {
            this.params = params;
        }

        @Override
        public String getDisplayName( int invocationIndex )
        {
            return "[" + invocationIndex + "] "
                   + Stream.of( params ).map( Object::toString ).collect( Collectors.joining( ", " ) );
        }

        @Override
        public List<Extension> getAdditionalExtensions()
        {
            return Arrays.asList(
                    ( TestInstancePostProcessor ) this::postProcessTestInstance );
        }

        protected void postProcessTestInstance( Object testInstance, ExtensionContext context ) throws Exception
        {
            Class<?> clazz = testInstance.getClass();
            List<Field> fields = hierarchy( clazz )
                    .map( Class::getDeclaredFields )
                    .flatMap( Stream::of )
                    .filter( f -> isAnnotated( f, Parameter.class ) )
                    .sorted( Comparator.comparing( f -> ( Integer ) f.getAnnotation( Parameter.class ).value() ) )
                    .collect( Collectors.toList() );
            if ( params.length != fields.size() )
            {
                throw new TestInstantiationException(
                        "Expected " + fields.size() + " parameters bug got " + params.length + " when instantiating "
                                                     + clazz.getName() );
            }
            for ( int i = 0; i < fields.size(); i++ )
            {
                Field f = fields.get( i );
                f.setAccessible( true );
                f.set( testInstance, DefaultArgumentConverter.INSTANCE.convert( params[i], f.getType() ) );
            }
        }

        protected Stream<Class<?>> hierarchy( Class<?> clazz )
        {
            Class<?> superclass = clazz.getSuperclass();
            return Stream.concat( Stream.of( clazz ), superclass != null ? hierarchy( superclass ) : Stream.empty() );
        }

    }

}