IDEA 报错：no tests were found 和 UnsupportedOperationException

这里分享一个 IntelliJ IDEA 运行 @Test 测试方法失败的问题以及解决方法。

测试类如下：

public class DaoTest {
​
    @Test
    public void register() {
        String date = new SimpleDateFormat("yyyy-MM-dd").format(new Date());
        User user = new User("renda", "123456", "123456789456", date);
        System.out.println("注册成功");
    }
​
}

运行报错：

Error:Internal error: (java.lang.UnsupportedOperationException) empty.min
java.lang.UnsupportedOperationException: empty.min
    at scala.collection.TraversableOnce.min(TraversableOnce.scala:225)
    at scala.collection.TraversableOnce.min$(TraversableOnce.scala:223)
    at scala.collection.AbstractTraversable.min(Traversable.scala:108)
    at org.jetbrains.jps.incremental.scala.ScalaCompilerReferenceIndexBuilder.getTargetTimestamps(ScalaCompilerReferenceIndexBuilder.scala:53)
    at org.jetbrains.jps.incremental.scala.ScalaCompilerReferenceIndexBuilder.getAllClassesInfo(ScalaCompilerReferenceIndexBuilder.scala:99)
    at org.jetbrains.jps.incremental.scala.ScalaCompilerReferenceIndexBuilder.buildFinished(ScalaCompilerReferenceIndexBuilder.scala:33)
    at org.jetbrains.jps.incremental.IncProjectBuilder.runBuild(IncProjectBuilder.java:468)
    at org.jetbrains.jps.incremental.IncProjectBuilder.build(IncProjectBuilder.java:190)
    at org.jetbrains.jps.cmdline.BuildRunner.runBuild(BuildRunner.java:138)
    at org.jetbrains.jps.cmdline.BuildSession.runBuild(BuildSession.java:297)
    at org.jetbrains.jps.cmdline.BuildSession.run(BuildSession.java:130)
    at org.jetbrains.jps.cmdline.BuildMain$MyMessageHandler.lambda$channelRead0$0(BuildMain.java:218)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:834)

执行 maven clean 之后再运行测试方法会报错：

no tests were found

后来发现是项目的 .idea 文件夹和 .iml 文件因为路径不匹配引起的问题，于是删掉 .idea 文件夹和 .iml 文件，重新用 IDEA 打开项目，重新生成 .idea 文件夹和 .iml 文件，测试方法可以正常运行。