在 JUnit4 中使用 SystemOutRule 获取不到控制台的标准输出内容
自己在练习《Spring实战》第四版这本书的第一章例子时发现在测试部分无法使用 SystemOutRule 获取到 System.out 或者 PrintStream 输出到控制台的内容。测试类import org.junit.Rule;import org.junit.Test;
import org.junit.contrib.java.lang.system.StandardOutputStreamLog;
import org.junit.contrib.java.lang.system.SystemErrRule;
import org.junit.contrib.java.lang.system.SystemOutRule;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.junit4.SpringRunner;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = KnightConfig.class)
public class SlayDragonQuestTest {
@Rule
public final StandardOutputStreamLog log = new StandardOutputStreamLog();
@Rule
public final SystemOutRule systemOutRule = new SystemOutRule().enableLog();
@Rule
public final SystemErrRule systemErrRule = new SystemErrRule().enableLog();
@Autowired
private Knight knight;
@Test
public void shouldBeNotNull() {
Assert.assertNotNull(knight);
}
@Test
public void writesTextToSystemErr() {
System.err.print("hello world");
Assert.assertEquals("hello world", systemErrRule.getLog());
}
@Test
public void shouldBeEqual() {
systemOutRule.clearLog();
knight.embarkOnQuest();
// System.out.println("Embarking on quest to slay the dragon!");
Assert.assertEquals("Embarking on quest to slay the dragon!\r\n", systemOutRule.getLog());
}
}当我执行下面这个测试方法 shouldBeEqual()，结果显示 SystemOutRule 的 getLog() 方法获取的控制台输出内容是空的。@Test
public void shouldBeEqual() {
systemOutRule.clearLog();
knight.embarkOnQuest();
// System.out.println("Embarking on quest to slay the dragon!");
Assert.assertEquals("Embarking on quest to slay the dragon!\r\n", systemOutRule.getLog());
}点开 Click to see difference显示 systemOutRule.getLog() 并没有获取到控制台的输出内容，而第一张结果图显示控制台是有输出内容的。配置类package com.hb.config;
import com.hb.impl.BraveKnight;
import com.hb.impl.SlayDragonQuest;
import com.hb.interfaces.Knight;
import com.hb.interfaces.Quest;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class KnightConfig {
@Bean
public Knight knight() {
return new BraveKnight(quest());
}
@Bean
public Quest quest() {
return new SlayDragonQuest(System.out);
}
}BraveKnight 类和 Knight 接口public class BraveKnight implements Knight {
private Quest quest;
public BraveKnight(Quest quest) {
this.quest = quest;
}
@Override
public void embarkOnQuest() {
quest.embark();
}
}
public interface Knight {
void embarkOnQuest();
}SlayDragonQuest 类和 Quest 接口package com.hb.impl;
import com.hb.interfaces.Quest;
import java.io.PrintStream;
public class SlayDragonQuest implements Quest {
private PrintStream stream;
public SlayDragonQuest(PrintStream stream) {
this.stream = stream;
}
@Override
public void embark() {
stream.println("Embarking on quest to slay the dragon!");
}
}
public interface Quest {
void embark();
}刚开始我以为是构造 SlayDragonQuest 类注入的 PrintStream 有问题，于是我新建了一个程序入口看看 BraveKnight 类的实际输出了什么。package com.hb;
import com.hb.config.KnightConfig;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class Knight {
public static void main(String[] args) throws Exception {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(KnightConfig.class);
com.hb.interfaces.Knight knight = context.getBean(com.hb.interfaces.Knight.class);
knight.embarkOnQuest();
context.close();
}
}结果显示说明通过 PrintStream 调用 Println() 方法是能够将内容输出到控制台的。那么也就说明了 SystemOutRule 的 getLog() 方法并没有获取到控制台的输出内容。接着我注释了测试方法 shouldBeEqual() 中的 knight.embarkOnQuest(); 而直接使用 System.out.println() 方法。@Test
public void shouldBeEqual() {
systemOutRule.clearLog();
// knight.embarkOnQuest();
System.out.println("Embarking on quest to slay the dragon!");
Assert.assertEquals("Embarking on quest to slay the dragon!\r\n", systemOutRule.getLog());
}结果还是一样失败
操作系统：Win10
IDE：Intellij IDEA 2021.1.2
依赖的包(pom.xml)：<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>5.2.15.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>5.2.15.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>5.2.15.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>5.2.15.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>5.2.15.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>5.2.15.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>5.2.15.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aspects</artifactId>
<version>5.2.15.RELEASE</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-project-info-reports-plugin</artifactId>
<version>3.0.0</version>
<type>maven-plugin</type>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<version>4.2.0</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.9.7</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.9</version>
</dependency>
<dependency>
<groupId>com.github.stefanbirkner</groupId>
<artifactId>system-rules</artifactId>
<version>1.16.0</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.7.25</version>
<scope>test</scope>
</dependency>
</dependencies>在此请教下各位问题到底出在哪里
输出存为变量再比较吧 改变一下输出 不太清楚
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