flink-tests/src/test/java/org/apache/flink/test/plugin/PluginLoaderTest.java

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 * 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
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 * Unless required by applicable law or agreed to in writing, software
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package org.apache.flink.test.plugin;

import org.apache.flink.core.plugin.PluginDescriptor;
import org.apache.flink.core.plugin.PluginLoader;
import org.apache.flink.test.plugin.jar.plugina.TestServiceA;

import org.junit.Assert;
import org.junit.Test;

import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Iterator;

/** Test for {@link PluginLoader}. */
public class PluginLoaderTest extends PluginTestBase {

    @Test
    public void testPluginLoading() throws Exception {

        final URL classpathA = createPluginJarURLFromString(PLUGIN_A);

        String[] parentPatterns = {TestSpi.class.getName(), OtherTestSpi.class.getName()};
        PluginDescriptor pluginDescriptorA =
                new PluginDescriptor("A", new URL[] {classpathA}, parentPatterns);
        URLClassLoader pluginClassLoaderA =
                PluginLoader.createPluginClassLoader(
                        pluginDescriptorA, PARENT_CLASS_LOADER, new String[0]);
        Assert.assertNotEquals(PARENT_CLASS_LOADER, pluginClassLoaderA);
        final PluginLoader pluginLoaderA = new PluginLoader("test-plugin", pluginClassLoaderA);

        Iterator<TestSpi> testSpiIteratorA = pluginLoaderA.load(TestSpi.class);

        Assert.assertTrue(testSpiIteratorA.hasNext());

        TestSpi testSpiA = testSpiIteratorA.next();

        Assert.assertFalse(testSpiIteratorA.hasNext());

        Assert.assertNotNull(testSpiA.testMethod());

        Assert.assertEquals(
                TestServiceA.class.getCanonicalName(), testSpiA.getClass().getCanonicalName());
        // The plugin must return the same class loader as the one used to load it.
        Assert.assertEquals(pluginClassLoaderA, testSpiA.getClassLoader());
        Assert.assertEquals(pluginClassLoaderA, testSpiA.getClass().getClassLoader());

        // Looks strange, but we want to ensure that those classes are not instance of each other
        // because they were
        // loaded by different classloader instances because the plugin loader uses
        // child-before-parent order.
        Assert.assertFalse(testSpiA instanceof TestServiceA);

        // In the following we check for isolation of classes between different plugin loaders.
        final PluginLoader secondPluginLoaderA =
                PluginLoader.create(pluginDescriptorA, PARENT_CLASS_LOADER, new String[0]);

        TestSpi secondTestSpiA = secondPluginLoaderA.load(TestSpi.class).next();
        Assert.assertNotNull(secondTestSpiA.testMethod());

        // Again, this looks strange, but we expect classes with the same name, that are not equal.
        Assert.assertEquals(
                testSpiA.getClass().getCanonicalName(),
                secondTestSpiA.getClass().getCanonicalName());
        Assert.assertNotEquals(testSpiA.getClass(), secondTestSpiA.getClass());
    }

    @Test
    public void testClose() throws MalformedURLException {
        final URL classpathA = createPluginJarURLFromString(PLUGIN_A);

        String[] parentPatterns = {TestSpi.class.getName()};
        PluginDescriptor pluginDescriptorA =
                new PluginDescriptor("A", new URL[] {classpathA}, parentPatterns);
        URLClassLoader pluginClassLoaderA =
                PluginLoader.createPluginClassLoader(
                        pluginDescriptorA, PARENT_CLASS_LOADER, new String[0]);

        final PluginLoader pluginLoaderA = new PluginLoader("test-plugin", pluginClassLoaderA);
        pluginLoaderA.close();

        Assert.assertThrows(
                ClassNotFoundException.class,
                () -> pluginClassLoaderA.loadClass(junit.framework.Test.class.getName()));
    }
}