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
17package com.google.common.testing;
18
19import com.google.common.annotations.Beta;
20
21import java.util.ArrayList;
22import java.util.Collections;
23import java.util.List;
24import java.util.logging.Handler;
25import 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
55public 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