/*
    * 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 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.PathableClassLoader;
  import org.apache.commons.logging.PathableTestSuite;
  
  /**
   * Tests for the PathableTestSuite and PathableClassLoader functionality,
   * where lookup order for the PathableClassLoader is child-first.
   * <p>
   * These tests assume:
   * <ul>
   * <li>junit is in system classpath
   * <li>nothing else is in system classpath
   * </ul>
   */
  
  public class ChildFirstTestCase extends TestCase {
      
      /**
       * Set up a custom classloader hierarchy for this test case.
       * The hierarchy is:
       * <ul>
       * <li> contextloader: child-first.
       * <li> childloader: child-first, used to load test case.
       * <li> parentloader: child-first, parent is the bootclassloader.
       * </ul>
       */
      public static Test suite() throws Exception {
          Class thisClass = ChildFirstTestCase.class;
          ClassLoader thisClassLoader = thisClass.getClassLoader();
          
          // Make the parent a direct child of the bootloader to hide all
          // other classes in the system classpath
          PathableClassLoader parent = new PathableClassLoader(null);
          parent.setParentFirst(false);
          
          // 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 classloader that loaded
          // this class, so use that as the source for future access to classes
          // from the junit package.
          parent.useExplicitLoader("junit.", thisClassLoader);
          
          // Make the commons-logging.jar classes visible via the parent
          parent.addLogicalLib("commons-logging");
          
          // Create a child classloader to load the test case through
          PathableClassLoader child = new PathableClassLoader(parent);
          child.setParentFirst(false);
          
          // Obviously, the child classloader needs to have the test classes
          // in its path!
          child.addLogicalLib("testclasses");
          child.addLogicalLib("commons-logging-adapters");
          
          // Create a third classloader to be the context classloader.
          PathableClassLoader context = new PathableClassLoader(child);
          context.setParentFirst(false);
  
          // reload this class via the child classloader
          Class testClass = child.loadClass(thisClass.getName());
          
          // and return our custom TestSuite class
          return new PathableTestSuite(testClass, context);
      }
  
      /**
       * Utility method to return the set of all classloaders in the
       * parent chain starting from the one that loaded the class for
       * this object instance.
       */
      private Set getAncestorCLs() {
          Set s = new HashSet();
         ClassLoader cl = this.getClass().getClassLoader();
         while (cl != null) {
             s.add(cl);
             cl = cl.getParent();
         }
         return s;
     }
 
     /**
      * Test that the classloader hierarchy is as expected, and that
      * calling loadClass() on various classloaders works as expected.
      * Note that for this test case, parent-first classloading is
      * in effect.
      */
     public void testPaths() throws Exception {
         // the context classloader is not expected to be null
         ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
         assertNotNull("Context classloader is null", contextLoader);
         assertEquals("Context classloader has unexpected type",
                 PathableClassLoader.class.getName(),
                 contextLoader.getClass().getName());
         
         // the classloader that loaded this class is obviously not null
         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 classloader's parent
         // is the loader that loaded this test case.
         assertSame("Context classloader is not child of thisLoader",
                 thisLoader, contextLoader.getParent());
 
         // thisLoader's parent should be available
         ClassLoader parentLoader = thisLoader.getParent();
         assertNotNull("Parent classloader is null", parentLoader);
         assertEquals("Parent classloader has unexpected type",
                 PathableClassLoader.class.getName(),
                 parentLoader.getClass().getName());
         
         // parent should have a parent of null
         assertNull("Parent classloader has non-null parent", parentLoader.getParent());
 
         // getSystemClassloader is not a PathableClassLoader; it's of a
         // built-in type. This also verifies that system classloader is none of
         // (context, child, parent).
         ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
         assertNotNull("System classloader is null", systemLoader);
         assertFalse("System classloader has unexpected type",
                 PathableClassLoader.class.getName().equals(
                         systemLoader.getClass().getName()));
 
         // junit classes should be visible; their classloader is not
         // in the hierarchy of parent classloaders for this class,
         // though it is accessable due to trickery in the PathableClassLoader.
         Class junitTest = contextLoader.loadClass("junit.framework.Test");
         Set ancestorCLs = getAncestorCLs();
         assertFalse("Junit not loaded by ancestor classloader", 
                 ancestorCLs.contains(junitTest.getClassLoader()));
 
         // jcl api classes should be visible only via the parent
         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 classloaders are child-first we should see the child one.
         Class log4jClass = contextLoader.loadClass("org.apache.commons.logging.impl.Log4JLogger");
         assertSame("Log4JLogger not loaded via child", 
                 log4jClass.getClassLoader(), thisLoader);
         
         // test classes should be visible via the child only
         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 {
             Class noSuchClass = contextLoader.loadClass("no.such.class");
             fail("Class no.such.class is unexpectedly available");
             assertNotNull(noSuchClass); // silence warning about unused var
         } catch(ClassNotFoundException ex) {
             // ok
         }
 
         // String class classloader is null
         Class stringClass = contextLoader.loadClass("java.lang.String");
         assertNull("String class classloader is not null!",
                 stringClass.getClassLoader());
     }
     
     /**
      * Test that the various flavours of ClassLoader.getResource work as expected.
      */
     public void testResource() {
         URL resource;
         
         ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
         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 accessable only to parent classloader
         resource = childLoader.getResource("org/apache/commons/logging/Log.class");
         assertNotNull("Unable to locate Log.class resource", resource);
         
         // getResource where it is accessable only to child classloader
         resource = childLoader.getResource("org/apache/commons/logging/PathableTestSuite.class");
         assertNotNull("Unable to locate PathableTestSuite.class resource", resource);
 
         // getResource where it is accessable to both classloaders. The one visible
         // to the child should be returned. The URL returned will be of form
         //  jar:file:/x/y.jar!path/to/resource. The filename part should include the jarname
         // of form commons-logging-adapters-nnnn.jar, not commons-logging-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("/commons-logging-adapters-1.") > 0);
     }
     
     /**
      * Test that the various flavours of ClassLoader.getResources work as expected.
      */
     public void testResources() throws Exception {
         Enumeration resources;
         URL[] urls;
         
         // verify the classloader hierarchy
         ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
         ClassLoader childLoader = contextLoader.getParent();
         ClassLoader parentLoader = childLoader.getParent();
         ClassLoader bootLoader = parentLoader.getParent();
         assertNull("Unexpected classloader hierarchy", bootLoader);
         
         // getResources where no instances exist
         resources = childLoader.getResources("nosuchfile");
         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 (child-resource, parent-resource).
         //
         // IMPORTANT: due to the fact that in java 1.4 and earlier method
         // ClassLoader.getResources is final it isn't possible for PathableClassLoader
         // to override this. So even when child-first is enabled the resource order
         // is still (parent-resources, child-resources). This test verifies the expected
         // behaviour - even though it's not the desired behaviour.
         
         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
         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("/commons-logging-1.") > 0);
         assertTrue("Incorrect source for Log4JLogger class",
                 urlsToStrings[1].indexOf("/commons-logging-adapters-1.") > 0);
     }
 
     /**
      * Utility method to convert an enumeration-of-URLs into an array of URLs.
      */
     private static URL[] toURLArray(Enumeration e) {
         ArrayList l = new ArrayList();
         while (e.hasMoreElements()) {
             URL u = (URL) e.nextElement();
             l.add(u);
         }
         URL[] tmp = new URL[l.size()];
         return (URL[]) l.toArray(tmp);
     }
 
     /**
      * Test that getResourceAsStream works.
      */
     public void testResourceAsStream() throws Exception {
         java.io.InputStream is;
         
         // verify the classloader hierarchy
         ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
         ClassLoader childLoader = contextLoader.getParent();
         ClassLoader parentLoader = childLoader.getParent();
         ClassLoader bootLoader = parentLoader.getParent();
         assertNull("Unexpected classloader hierarchy", bootLoader);
         
         // getResourceAsStream where no instances exist
         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.
     }
 }