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      1 /*
      2  * Copyright (C) 2008 The Guava Authors
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  * http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.google.common.testing;
     18 
     19 import com.google.common.annotations.Beta;
     20 
     21 import java.util.ArrayList;
     22 import java.util.Collections;
     23 import java.util.List;
     24 import java.util.logging.Handler;
     25 import java.util.logging.LogRecord;
     26 
     27 /**
     28  * Tests may use this to intercept messages that are logged by the code under
     29  * test.  Example:
     30  * <pre>
     31  *   TestLogHandler handler;
     32  *
     33  *   protected void setUp() throws Exception {
     34  *     super.setUp();
     35  *     handler = new TestLogHandler();
     36  *     SomeClass.logger.addHandler(handler);
     37  *     addTearDown(new TearDown() {
     38  *       public void tearDown() throws Exception {
     39  *         SomeClass.logger.removeHandler(handler);
     40  *       }
     41  *     });
     42  *   }
     43  *
     44  *   public void test() {
     45  *     SomeClass.foo();
     46  *     LogRecord firstRecord = handler.getStoredLogRecords().get(0);
     47  *     assertEquals("some message", firstRecord.getMessage());
     48  *   }
     49  * </pre>
     50  *
     51  * @author Kevin Bourrillion
     52  * @since 10.0
     53  */
     54 @Beta
     55 public class TestLogHandler extends Handler {
     56   /** We will keep a private list of all logged records */
     57   private final List<LogRecord> list =
     58       Collections.synchronizedList(new ArrayList<LogRecord>());
     59 
     60   /**
     61    * Adds the most recently logged record to our list.
     62    */
     63   @Override
     64   public void publish(LogRecord record) {
     65     list.add(record);
     66   }
     67 
     68   @Override
     69   public void flush() { }
     70 
     71   @Override
     72   public void close() { }
     73 
     74   public void clear() {
     75     list.clear();
     76   }
     77 
     78   /**
     79    * Fetch the list of logged records
     80    * @return unmodifiable LogRecord list of all logged records
     81    */
     82   public List<LogRecord> getStoredLogRecords() {
     83     List<LogRecord> result = new ArrayList<LogRecord>(list);
     84     return Collections.unmodifiableList(result);
     85   }
     86 }
     87