/*
    * 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.
   */
  package org.apache.commons.logging.pathable;
  
  import static org.junit.Assert.assertNotEquals;
  
  import java.io.InputStream;
  import java.net.URL;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Enumeration;
  import java.util.HashSet;
  import java.util.Set;
  
  import junit.framework.Test;
  import junit.framework.TestCase;
  
  import org.apache.commons.logging.Artifacts;
  import org.apache.commons.logging.PathableClassLoader;
  import org.apache.commons.logging.PathableTestSuite;
  
  /**
   * Tests for the PathableTestSuite and PathableClassLoader functionality,
   * where lookup order for the PathableClassLoader is parent-first.
   * <p>
   * These tests assume:
   * <ul>
   * <li>junit is in system classpath
   * <li>nothing else is in system classpath
   * </ul>
   */
  
  public class ParentFirstTestCase extends TestCase {
  
      /**
       * Sets up a custom class loader hierarchy for this test case.
       * The hierarchy is:
       * <ul>
       * <li> contextloader: parent-first.
       * <li> childloader: parent-first, used to load test case.
       * <li> parentloader: parent-first, parent is the boot class loader.
       * </ul>
       */
      public static Test suite() throws Exception {
          final Class<ParentFirstTestCase> thisClass = ParentFirstTestCase.class;
          final ClassLoader thisClassLoader = thisClass.getClassLoader();
  
          // Make the parent a direct child of the bootloader to hide all
          // other classes in the system classpath
          final PathableClassLoader parent = new PathableClassLoader(null);
  
          // Make the junit classes visible as a special case, as junit
          // won't be able to call this class at all without this. The
          // junit classes must be visible from the class loader that loaded
          // this class, so use that as the source for future access to classes
          // from the junit package.
          parent.useExplicitLoader("junit.", thisClassLoader);
          parent.useExplicitLoader("org.junit.", thisClassLoader);
  
          // make the commons-logging.jar classes visible via the parent
          parent.addLogicalLib("commons-logging");
  
          // create a child class loader to load the test case through
          final PathableClassLoader child = new PathableClassLoader(parent);
  
          // obviously, the child class loader needs to have the test classes
          // in its path!
          child.addLogicalLib("testclasses");
          child.addLogicalLib("commons-logging-adapters");
  
          // create a third class loader to be the context class loader.
          final PathableClassLoader context = new PathableClassLoader(child);
  
          // reload this class via the child class loader
          final Class<?> testClass = child.loadClass(thisClass.getName());
  
          // and return our custom TestSuite class
          return new PathableTestSuite(testClass, context);
      }
  
      /**
       * Utility method to convert an enumeration-of-URLs into an array of URLs.
       */
      private static URL[] toURLArray(final Enumeration<URL> e) {
          final ArrayList<URL> l = new ArrayList<>();
         while (e.hasMoreElements()) {
             l.add(e.nextElement());
         }
         final URL[] tmp = new URL[l.size()];
         return l.toArray(tmp);
     }
 
     /**
      * Utility method to return the set of all class loaders in the
      * parent chain starting from the one that loaded the class for
      * this object instance.
      */
     private Set<ClassLoader> getAncestorCLs() {
         final Set<ClassLoader> s = new HashSet<>();
         ClassLoader cl = this.getClass().getClassLoader();
         while (cl != null) {
             s.add(cl);
             cl = cl.getParent();
         }
         return s;
     }
 
     /**
      * Test that the class loader hierarchy is as expected, and that
      * calling loadClass() on various class loaders works as expected.
      * Note that for this test case, parent-first classloading is
      * in effect.
      */
     public void testPaths() throws Exception {
         // the context class loader is not expected to be null
         final ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
         assertNotNull("Context class loader is null", contextLoader);
         assertEquals("Context class loader has unexpected type",
                 PathableClassLoader.class.getName(),
                 contextLoader.getClass().getName());
 
         // the class loader that loaded this class is obviously not null
         final ClassLoader thisLoader = this.getClass().getClassLoader();
         assertNotNull("thisLoader is null", thisLoader);
         assertEquals("thisLoader has unexpected type",
                 PathableClassLoader.class.getName(),
                 thisLoader.getClass().getName());
 
         // the suite method specified that the context class loader's parent
         // is the loader that loaded this test case.
         assertSame("Context class loader is not child of thisLoader",
                 thisLoader, contextLoader.getParent());
 
         // thisLoader's parent should be available
         final ClassLoader parentLoader = thisLoader.getParent();
         assertNotNull("Parent class loader is null", parentLoader);
         assertEquals("Parent class loader has unexpected type",
                 PathableClassLoader.class.getName(),
                 parentLoader.getClass().getName());
 
         // parent should have a parent of null
         assertNull("Parent class loader has non-null parent", parentLoader.getParent());
 
         // getSystemClassloader is not a PathableClassLoader; it's of a
         // built-in type. This also verifies that system class loader is none of
         // (context, child, parent).
         final ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
         assertNotNull("System class loader is null", systemLoader);
         assertNotEquals("System class loader has unexpected type", PathableClassLoader.class.getName(),
                 systemLoader.getClass().getName());
 
         // junit classes should be visible; their class loader is not
         // in the hierarchy of parent class loaders for this class,
         // though it is accessible due to trickery in the PathableClassLoader.
         final Class<?> junitTest = contextLoader.loadClass("junit.framework.Test");
         final Set<?> ancestorCLs = getAncestorCLs();
         assertFalse("Junit not loaded by ancestor class loader",
                 ancestorCLs.contains(junitTest.getClassLoader()));
 
         // jcl api classes should be visible only via the parent
         final Class<?> logClass = contextLoader.loadClass("org.apache.commons.logging.Log");
         assertSame("Log class not loaded via parent",
                 logClass.getClassLoader(), parentLoader);
 
         // jcl adapter classes should be visible via both parent and child. However
         // as the class loaders are parent-first we should see the parent one.
         final Class<?> log4jClass = contextLoader.loadClass("org.apache.commons.logging.impl.Log4JLogger");
         assertSame("Log4JLogger not loaded via parent",
                 log4jClass.getClassLoader(), parentLoader);
 
         // test classes should be visible via the child only
         final Class<?> testClass = contextLoader.loadClass("org.apache.commons.logging.PathableTestSuite");
         assertSame("PathableTestSuite not loaded via child",
                 testClass.getClassLoader(), thisLoader);
 
         // test loading of class that is not available
         try {
             final Class<?> noSuchClass = contextLoader.loadClass("no.such.class");
             fail("Class no.such.class is unexpectedly available");
             assertNotNull(noSuchClass); // silence warning about unused var
         } catch (final ClassNotFoundException ex) {
             // ok
         }
 
         // String class class loader is null
         final Class<?> stringClass = contextLoader.loadClass("java.lang.String");
         assertNull("String class class loader is not null!",
                 stringClass.getClassLoader());
     }
 
     /**
      * Test that the various flavors of ClassLoader.getResource work as expected.
      */
     public void testResource() {
         URL resource;
 
         final ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
         final ClassLoader childLoader = contextLoader.getParent();
 
         // getResource where it doesn't exist
         resource = childLoader.getResource("nosuchfile");
         assertNull("Non-null URL returned for invalid resource name", resource);
 
         // getResource where it is accessible only to parent class loader
         resource = childLoader.getResource("org/apache/commons/logging/Log.class");
         assertNotNull("Unable to locate Log.class resource", resource);
 
         // getResource where it is accessible only to child class loader
         resource = childLoader.getResource("org/apache/commons/logging/PathableTestSuite.class");
         assertNotNull("Unable to locate PathableTestSuite.class resource", resource);
 
         // getResource where it is accessible to both class loaders. The one visible
         // to the parent should be returned. The URL returned will be of form
         //  jar:file:/x/y.jar!path/to/resource. The file name part should include the jarname
         // of form commons-logging-nnnn.jar, not commons-logging-adapters-nnnn.jar
         resource = childLoader.getResource("org/apache/commons/logging/impl/Log4JLogger.class");
         assertNotNull("Unable to locate Log4JLogger.class resource", resource);
         assertTrue("Incorrect source for Log4JLogger class",
                 resource.toString().indexOf(Artifacts.getMainJarName()) > 0);
     }
 
     /**
      * Test that getResourceAsStream works.
      */
     public void testResourceAsStream() throws Exception {
         // verify the class loader hierarchy
         final ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
         final ClassLoader childLoader = contextLoader.getParent();
         final ClassLoader parentLoader = childLoader.getParent();
         final ClassLoader bootLoader = parentLoader.getParent();
         assertNull("Unexpected class loader hierarchy", bootLoader);
 
         // getResourceAsStream where no instances exist
         InputStream is = childLoader.getResourceAsStream("nosuchfile");
         assertNull("Invalid resource returned non-null stream", is);
 
         // getResourceAsStream where resource does exist
         is = childLoader.getResourceAsStream("org/apache/commons/logging/Log.class");
         assertNotNull("Null returned for valid resource", is);
         is.close();
 
         // It would be nice to test parent-first ordering here, but that would require
         // having a resource with the same name in both the parent and child loaders,
         // but with different contents. That's a little tricky to set up so we'll
         // skip that for now.
     }
 
     /**
      * Test that the various flavors of ClassLoader.getResources work as expected.
      */
     public void testResources() throws Exception {
         // verify the class loader hierarchy
         final ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
         final ClassLoader childLoader = contextLoader.getParent();
         final ClassLoader parentLoader = childLoader.getParent();
         final ClassLoader bootLoader = parentLoader.getParent();
         assertNull("Unexpected class loader hierarchy", bootLoader);
 
         // getResources where no instances exist
         Enumeration<URL> resources = childLoader.getResources("nosuchfile");
         URL[] urls = toURLArray(resources);
         assertEquals("Non-null URL returned for invalid resource name", 0, urls.length);
 
         // getResources where the resource only exists in the parent
         resources = childLoader.getResources("org/apache/commons/logging/Log.class");
         urls = toURLArray(resources);
         assertEquals("Unexpected number of Log.class resources found", 1, urls.length);
 
         // getResources where the resource only exists in the child
         resources = childLoader.getResources("org/apache/commons/logging/PathableTestSuite.class");
         urls = toURLArray(resources);
         assertEquals("Unexpected number of PathableTestSuite.class resources found", 1, urls.length);
 
         // getResources where the resource exists in both.
         // resources should be returned in order (parent-resource, child-resource)
         resources = childLoader.getResources("org/apache/commons/logging/impl/Log4JLogger.class");
         urls = toURLArray(resources);
         assertEquals("Unexpected number of Log4JLogger.class resources found", 2, urls.length);
 
         // There is no gaurantee about the ordering of results returned from getResources
         // To make this test portable across JVMs, sort the string to give them a known order
         final String[] urlsToStrings = new String[2];
         urlsToStrings[0] = urls[0].toString();
         urlsToStrings[1] = urls[1].toString();
         Arrays.sort(urlsToStrings);
         assertTrue("Incorrect source for Log4JLogger class",
                 urlsToStrings[0].indexOf(Artifacts.getAdaptersJarName()) > 0);
         assertTrue("Incorrect source for Log4JLogger class",
                 urlsToStrings[1].indexOf(Artifacts.getMainJarName()) > 0);
 
     }
 }