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
27import 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
57public 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
66  public void publish(@Nullable LogRecord record) {
67    list.add(record);
68  }
69
70  @Override
71  public void flush() {}
72
73  @Override
74  public void close() {}
75
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   */
84  public List<LogRecord> getStoredLogRecords() {
85    List<LogRecord> result = new ArrayList<LogRecord>(list);
86    return Collections.unmodifiableList(result);
87  }
88}
89