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 import com.google.common.annotations.GwtCompatible;
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 import org.checkerframework.checker.nullness.qual.Nullable;
27
28 /**
29 * Tests may use this to intercept messages that are logged by the code under test. Example:
30 *
31 * <pre>
32 * TestLogHandler handler;
33 *
34 * protected void setUp() throws Exception {
35 * super.setUp();
36 * handler = new TestLogHandler();
37 * SomeClass.logger.addHandler(handler);
38 * addTearDown(new TearDown() {
39 * public void tearDown() throws Exception {
40 * SomeClass.logger.removeHandler(handler);
41 * }
42 * });
43 * }
44 *
45 * public void test() {
46 * SomeClass.foo();
47 * LogRecord firstRecord = handler.getStoredLogRecords().get(0);
48 * assertEquals("some message", firstRecord.getMessage());
49 * }
50 * </pre>
51 *
52 * @author Kevin Bourrillion
53 * @since 10.0
54 */
55 @Beta
56 @GwtCompatible
57 public class TestLogHandler extends Handler {
58 /** We will keep a private list of all logged records */
59 private final List<LogRecord> list = new ArrayList<>();
60
61 /** Adds the most recently logged record to our list. */
62 @Override
63 public synchronized void publish(@Nullable LogRecord record) {
64 list.add(record);
65 }
66
67 @Override
68 public void flush() {}
69
70 @Override
71 public void close() {}
72
73 public synchronized void clear() {
74 list.clear();
75 }
76
77 /** Returns a snapshot of the logged records. */
78 /*
79 * TODO(cpovirk): consider higher-level APIs here (say, assertNoRecordsLogged(),
80 * getOnlyRecordLogged(), getAndClearLogRecords()...)
81 *
82 * TODO(cpovirk): consider renaming this method to reflect that it takes a snapshot (and/or return
83 * an ImmutableList)
84 */
85 public synchronized List<LogRecord> getStoredLogRecords() {
86 List<LogRecord> result = new ArrayList<>(list);
87 return Collections.unmodifiableList(result);
88 }
89 }