我有一些正在测试的代码，它调用Java记录器来报告其状态。 在JUnit测试代码中，我想验证在这个日志记录器中创建了正确的日志条目。大致如下:
methodUnderTest(bool x){
if(x)
logger.info("x happened")
}
@Test tester(){
// perhaps setup a logger first.
methodUnderTest(true);
assertXXXXXX(loggedLevel(),Level.INFO);
}
我认为这可以用一个经过特别调整的记录器(或处理程序或格式化程序)来完成，但我更愿意重用现有的解决方案。(而且，老实说，我不清楚如何从记录器获得logRecord，但假设这是可能的。)
当前回答
使用Jmockit(1.21)，我能够编写这个简单的测试。 该测试确保只调用一次特定的ERROR消息。
@Test
public void testErrorMessage() {
final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger( MyConfig.class );
new Expectations(logger) {{
//make sure this error is happens just once.
logger.error( "Something went wrong..." );
times = 1;
}};
new MyTestObject().runSomethingWrong( "aaa" ); //SUT that eventually cause the error in the log.
}
其他回答
在我的案例中，我解决了如下的问题:
Logger root = (Logger) LoggerFactory.getLogger(CSVTasklet.class); //CSVTasklet is my target class
final Appender mockAppender = mock(Appender.class);
root.addAppender(mockAppender);
verify(mockAppender).doAppend(argThat((ArgumentMatcher) argument -> ((LoggingEvent) argument).getMessage().contains("No projects."))); // I checked "No projects." in the log
使用下面的代码。我在spring集成测试中使用相同的代码，其中我使用日志回日志。使用assertJobIsScheduled方法断言日志中打印的文本。
import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.spi.LoggingEvent;
import ch.qos.logback.core.Appender;
private Logger rootLogger;
final Appender mockAppender = mock(Appender.class);
@Before
public void setUp() throws Exception {
initMocks(this);
when(mockAppender.getName()).thenReturn("MOCK");
rootLogger = (Logger) LoggerFactory.getLogger(ch.qos.logback.classic.Logger.ROOT_LOGGER_NAME);
rootLogger.addAppender(mockAppender);
}
private void assertJobIsScheduled(final String matcherText) {
verify(mockAppender).doAppend(argThat(new ArgumentMatcher() {
@Override
public boolean matches(final Object argument) {
return ((LoggingEvent)argument).getFormattedMessage().contains(matcherText);
}
}));
}
如果我想做的只是看到一些字符串被记录(而不是验证确切的日志语句，这太脆弱了)，我所做的是将StdOut重定向到缓冲区，做一个contains，然后重置StdOut:
PrintStream original = System.out;
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
System.setOut(new PrintStream(buffer));
// Do something that logs
assertTrue(buffer.toString().contains(myMessage));
System.setOut(original);
另一个值得提及的想法是创建一个CDI生成器来注入记录器，这样模拟就变得容易了，尽管这是一个较老的主题。(而且它还提供了不必再声明“整个logger语句”的优势，但这已经跑题了)
例子:
创建要注入的记录器:
public class CdiResources {
@Produces @LoggerType
public Logger createLogger(final InjectionPoint ip) {
return Logger.getLogger(ip.getMember().getDeclaringClass());
}
}
限定符:
@Qualifier
@Retention(RetentionPolicy.RUNTIME)
@Target({TYPE, METHOD, FIELD, PARAMETER})
public @interface LoggerType {
}
在生产代码中使用记录器:
public class ProductionCode {
@Inject
@LoggerType
private Logger logger;
public void logSomething() {
logger.info("something");
}
}
在测试代码中测试记录器(给出一个easyMock示例):
@TestSubject
private ProductionCode productionCode = new ProductionCode();
@Mock
private Logger logger;
@Test
public void testTheLogger() {
logger.info("something");
replayAll();
productionCode.logSomething();
}
请注意，在Log4J 2中。X，公共接口org.apache.logging.log4j。Logger不包括setAppender()和removeAppender()方法。
但是，如果您没有做太花哨的事情，您应该能够将它强制转换为实现类org.apache.logging.log4j.core。记录器，它公开了这些方法。
这里有一个Mockito和AssertJ的例子:
// Import the implementation class rather than the API interface
import org.apache.logging.log4j.core.Logger;
// Cast logger to implementation class to get access to setAppender/removeAppender
Logger log = (Logger) LogManager.getLogger(MyClassUnderTest.class);
// Set up the mock appender, stubbing some methods Log4J needs internally
Appender appender = mock(Appender.class);
when(appender.getName()).thenReturn("Mock Appender");
when(appender.isStarted()).thenReturn(true);
log.addAppender(appender);
try {
new MyClassUnderTest().doSomethingThatShouldLogAnError();
} finally {
log.removeAppender(appender);
}
// Verify that we got an error with the expected message
ArgumentCaptor<LogEvent> logEventCaptor = ArgumentCaptor.forClass(LogEvent.class);
verify(appender).append(logEventCaptor.capture());
LogEvent logEvent = logEventCaptor.getValue();
assertThat(logEvent.getLevel()).isEqualTo(Level.ERROR);
assertThat(logEvent.getMessage().getFormattedMessage()).contains(expectedErrorMessage);
