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 import javax.annotation.Nullable;
28 
29 /**
30  * Tests may use this to intercept messages that are logged by the code under
31  * test.  Example:
32  * <pre>
33  *   TestLogHandler handler;
34  *
35  *   protected void setUp() throws Exception {
36  *     super.setUp();
37  *     handler = new TestLogHandler();
38  *     SomeClass.logger.addHandler(handler);
39  *     addTearDown(new TearDown() {
40  *       public void tearDown() throws Exception {
41  *         SomeClass.logger.removeHandler(handler);
42  *       }
43  *     });
44  *   }
45  *
46  *   public void test() {
47  *     SomeClass.foo();
48  *     LogRecord firstRecord = handler.getStoredLogRecords().get(0);
49  *     assertEquals("some message", firstRecord.getMessage());
50  *   }
51  * </pre>
52  *
53  * @author Kevin Bourrillion
54  * @since 10.0
55  */
56 @Beta
57 public class TestLogHandler extends Handler {
58   /** We will keep a private list of all logged records */
59   private final List<LogRecord> list =
60       Collections.synchronizedList(new ArrayList<LogRecord>());
61 
62   /**
63    * Adds the most recently logged record to our list.
64    */
65   @Override
publish(@ullable LogRecord record)66   public void publish(@Nullable LogRecord record) {
67     list.add(record);
68   }
69 
70   @Override
flush()71   public void flush() {}
72 
73   @Override
close()74   public void close() {}
75 
clear()76   public void clear() {
77     list.clear();
78   }
79 
80   /**
81    * Fetch the list of logged records
82    * @return unmodifiable LogRecord list of all logged records
83    */
getStoredLogRecords()84   public List<LogRecord> getStoredLogRecords() {
85     List<LogRecord> result = new ArrayList<LogRecord>(list);
86     return Collections.unmodifiableList(result);
87   }
88 }
89