JUnit-4.12：java.lang.NoClassDefFoundError: org/hamcrest/SelfDescribing

最近光在看别的，没咋写代码，都手生了。
写老师留的扫雷作业的测试类，在idea中直接导入了idea自带的Junit4.12包，运行测试类时报错
java.lang.NoClassDefFoundError: org/hamcrest/SelfDescribing
解决方法：导入idea自带的另一个包：hamcrest-core-1.3.jar
原因：
junit.jar: Includes the Hamcrest classes. The simple all-in-one solution to get started quickly.Starting with version 4.11, Hamcrest is no longer included in this jar.
junit-dep.jar: Only includes the JUnit classes but not Hamcrest. Lets you use a different Hamcrest version.

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往项目中导入jar包：
File –> Project Structure –> Modules –> dependencies –> 右侧绿色加号