junit使用问题记录（待补充）

1.使用junit4.9时报错，提示版本过低，应使用junit4.12以上版本。报错如下：

java.lang.ExceptionInInitializerError
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
	at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
	at org.junit.internal.builders.AnnotatedBuilder.buildRunner(AnnotatedBuilder.java:31)
	at org.junit.internal.builders.AnnotatedBuilder.runnerForClass(AnnotatedBuilder.java:24)
	at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
	at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:29)
	at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
	at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:24)
	at org.junit.internal.requests.FilterRequest.getRunner(FilterRequest.java:33)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:49)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: java.lang.IllegalStateException: SpringJUnit4ClassRunner requires JUnit 4.12 or higher.
	at org.springframework.util.Assert.state(Assert.java:73)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.<clinit>(SpringJUnit4ClassRunner.java:104)
	... 16 more

解决方法：

尝试降低版本为4.12,运行通过。

 

2.在springMVC中测试Service类时报错如下：

java.lang.IllegalStateException: Failed to load ApplicationContext
	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:125) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
	at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:107) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
.....
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.web.servlet.HandlerMapping]: Factory method 'resourceHandlerMapping' threw exception; nested exception is java.lang.IllegalStateException: No ServletContext set
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:579) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
.....

解决方法：

在测试类里使用了@ContextConfiguration(classes=RootConfig.class)来创建bean容器，RootConfig类定义里使用了@ComponentScan引入了其他配置类，其中WebConfig类也被引入。由于WebConfig类继承自WebMvcConfigurer类，有些bean必须在有Web容器时才能被初始化，导致出错。因此只需注释掉WebConfig类里的@Configuration声明，不将其用于创建bean容器即可。