区别很简单:

• 扩展 TestCase 是在 JUnit 3 中编写单元测试的方式(当然 JUnit 4 仍然支持它)
• 使用@Test注解是JUnit 4引入的方式

• extending TestCase is the way unit tests were written in JUnit 3 (of course it's still supported in JUnit 4)
• using the @Test annotation is the way introduced by JUnit 4

通常您应该选择注释路径，除非需要与 JUnit 3(和/或 Java 5 之前的 Java 版本)兼容.新方式有几个优点:

Generally you should choose the annotation path, unless compatibility with JUnit 3 (and/or a Java version earlier than Java 5) is needed. The new way has several advantages:

• @Test 注释 更明确，更容易在工具中支持(例如，通过这种方式可以轻松搜索所有测试)
• 可以使用@Before注释多个方法代码>/@BeforeClass 和 @After/@AfterClass提供更大的灵活性
• 支持 @Rule 注释ExpectedException
• 支持@Ignored 注释
• 支持使用 @RunWith 的替代测试运行器

要在 JUnit 3 TestCase 中测试预期的异常，您必须使文本显式.

To test for expected exceptions in a JUnit 3 TestCase you'd have to make the text explicit.

public void testMyException() {
  try {
    objectUnderTest.myMethod(EVIL_ARGUMENT);
    fail("myMethod did not throw an Exception!");
  } catch (MyException e) {
    // ok!
    // check for properties of exception here, if desired
  }
}

JUnit 5 引入了另一个 API 更改，但仍使用注释.新的 @Test 注释是 org.junit.jupiter.api.Test(旧"JUnit 4 是 org.junit.Test)，但它的工作原理与 JUnit 4 几乎相同.

JUnit 5 introduced yet another API change, but still uses annotations. The new @Test annotation is org.junit.jupiter.api.Test (the "old" JUnit 4 one was org.junit.Test), but it works pretty much the same as the JUnit 4 one.