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.GwtCompatible; 20 import java.util.ArrayList; 21 import java.util.Collections; 22 import java.util.List; 23 import java.util.logging.Handler; 24 import java.util.logging.LogRecord; 25 import javax.annotation.CheckForNull; 26 27 /** 28 * Tests may use this to intercept messages that are logged by the code under test. Example: 29 * 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 @GwtCompatible 55 public class TestLogHandler extends Handler { 56 /** We will keep a private list of all logged records */ 57 private final List<LogRecord> list = new ArrayList<>(); 58 59 /** Adds the most recently logged record to our list. */ 60 @Override publish(@heckForNull LogRecord record)61 public synchronized void publish(@CheckForNull LogRecord record) { 62 list.add(record); 63 } 64 65 @Override flush()66 public void flush() {} 67 68 @Override close()69 public void close() {} 70 clear()71 public synchronized void clear() { 72 list.clear(); 73 } 74 75 /** Returns a snapshot of the logged records. */ 76 /* 77 * TODO(cpovirk): consider higher-level APIs here (say, assertNoRecordsLogged(), 78 * getOnlyRecordLogged(), getAndClearLogRecords()...) 79 * 80 * TODO(cpovirk): consider renaming this method to reflect that it takes a snapshot (and/or return 81 * an ImmutableList) 82 */ getStoredLogRecords()83 public synchronized List<LogRecord> getStoredLogRecords() { 84 List<LogRecord> result = new ArrayList<>(list); 85 return Collections.unmodifiableList(result); 86 } 87 } 88