Log4j2：Junit 测试用例失败

Question

我正在为 log4j2 记录器编写 JUnit 测试用例，如下所示

import static org.junit.Assert.assertTrue;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class SampleLoggerTest {
    private ByteArrayOutputStream outContent = new ByteArrayOutputStream();
    private Logger logger = null;
    private PrintStream sysOut = System.out;

    @Before
    public void setUpStreams() {
        System.setOut(new PrintStream(outContent));
        logger = LogManager.getLogger(SampleLoggerTest.class);
    }

    @After
    public void restoreStreams() {
        System.setOut(sysOut);
    }

    @Test
    public void error() {
        logger.error("OnLogger");
        assertTrue(outContent.toString().contains("error"));
    }

    @Test
    public void debug() {
        logger.debug("OnLogger");
        assertTrue(outContent.toString().contains("debug"));
    }

    @Test
    public void fatal() {
        logger.fatal("OnLogger");
        assertTrue(outContent.toString().contains("fatal"));
    }

    @Test
    public void info() {
        logger.info("OnLogger");
        assertTrue(outContent.toString().contains("info"));
    }

    @Test
    public void warn() {
        logger.warn("OnLogger");
        assertTrue(outContent.toString().contains("warn"));
    }

    @Test
    public void trace() {
        logger.trace("OnLogger");
        assertTrue(outContent.toString().contains("trace"));
    }
}

但只有一个测试用例成功，即info() 我发现 outContent 包含第一个测试用例的日志语句 info() 并且它是成功的但对于其余测试用例 outContent 是空白的。

我在 restoreStreams() 中尝试了 flushing/closing 流，但没有成功，我还检查了控制台输出，那里正在打印所有内容，因为我将日志记录级别保持为 trace

任何人都可以帮助我找到我在其中缺少的东西吗？

控制台输出如下：

2018-04-19 11:53:31.636 INFO [main] [com.logger.SampleLoggerTest] [info] [com.logger.SampleLoggerTest.info(SampleLoggerTest.java:60)] - logger
2018-04-19 11:54:39.197 WARN [main] [com.logger.SampleLoggerTest] [warn] [com.logger.SampleLoggerTest.warn(SampleLoggerTest.java:69)] - logger
2018-04-19 11:54:41.790 DEBUG [main] [com.logger.SampleLoggerTest] [debug] [com.logger.SampleLoggerTest.debug(SampleLoggerTest.java:42)] - logger
2018-04-19 11:54:43.966 ERROR [main] [com.logger.SampleLoggerTest] [error] [com.logger.SampleLoggerTest.error(SampleLoggerTest.java:33)] - logger
2018-04-19 11:54:46.254 FATAL [main] [com.logger.SampleLoggerTest] [fatal] [com.logger.SampleLoggerTest.fatal(SampleLoggerTest.java:51)] - logger
2018-04-19 11:54:48.309 TRACE [main] [com.logger.SampleLoggerTest] [trace] [com.logger.SampleLoggerTest.trace(SampleLoggerTest.java:78)] - logger

Answer 1

log4j 仅初始化一次，因此 @Before 和 @After-方法不会影响 Log4J2。

你的 SampleLoggerTest 中的另一个问题是 ByteArrayOutputStream，当 SampleLoggerTest-Class 的一个实例被创建并可能被关闭时，它被初始化一次，当@Before-方法被第二次调用。

以下代码适用于我：

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Test;

public class SampleLoggerTest {
    private static ByteArrayOutputStream outContent;
    private static Logger logger = null;
    private static PrintStream printStream;

    @BeforeClass
    public static void init() {
        SampleLoggerTest.outContent = new ByteArrayOutputStream();
        SampleLoggerTest.printStream = new PrintStream(SampleLoggerTest.outContent);
        System.setOut(SampleLoggerTest.printStream);
        SampleLoggerTest.logger = LogManager.getLogger(SampleLoggerTest.class);
    }

    @Test
    public void debug() {
        SampleLoggerTest.logger.debug("OnLogger");
        Assert.assertTrue(SampleLoggerTest.outContent.toString().contains("DEBUG"));
    }

    @Test
    public void error() {
        SampleLoggerTest.logger.error("OnLogger");
        Assert.assertTrue(SampleLoggerTest.outContent.toString().contains("ERROR"));
    }

    @Test
    public void fatal() {
        SampleLoggerTest.logger.fatal("OnLogger");
        Assert.assertTrue(SampleLoggerTest.outContent.toString().contains("FATAL"));
    }

    @Test
    public void info() {
        SampleLoggerTest.logger.info("OnLogger");
        Assert.assertTrue(SampleLoggerTest.outContent.toString().contains("INFO"));
    }

    @Test
    public void trace() {
        SampleLoggerTest.logger.trace("OnLogger");
        Assert.assertTrue(SampleLoggerTest.outContent.toString().contains("TRACE"));
    }

    @Test
    public void warn() {
        SampleLoggerTest.logger.warn("OnLogger");
        Assert.assertTrue(SampleLoggerTest.outContent.toString().contains("WARN"));
    }
}

在执行最后一个 @Test 方法后，在我的例子中是 trace，ByteArrayOutputStream 看起来像这样：

10:44:32.848 [main] INFO  de.crm.tools.SampleLoggerTest - OnLogger
10:44:32.848 [main] WARN  de.crm.tools.SampleLoggerTest - OnLogger
10:44:47.601 [main] DEBUG de.crm.tools.SampleLoggerTest - OnLogger
10:44:47.601 [main] ERROR de.crm.tools.SampleLoggerTest - OnLogger
10:44:47.601 [main] FATAL de.crm.tools.SampleLoggerTest - OnLogger
10:44:47.601 [main] TRACE de.crm.tools.SampleLoggerTest - OnLogger

Log4j2：Junit 测试用例失败

Log4j2: Junit test cases are failing

java

junit4

log4j2