重构静态方法/静态字段以进行测试

Question

我有以下遗留代码:

public class MyLegacyClass
{
    private static final String jndiName = "java:comp/env/jdbc/LegacyDataSource"

    public static SomeLegacyClass doSomeLegacyStuff(SomeOtherLegacyClass legacyObj)
    {
       // do stuff using jndiName
    }
}

这个类在J2EE-Container中工作.

现在我想测试容器外面的类.

什么是最好的策略？基本上允许重构.

允许访问LegacyDataSource(测试不必是"纯"单元测试).

编辑:不允许引入其他运行时框架.

Answer 1

只是为了让@ Robin建议更具体的策略模式:(请注意,原始问题的公共API保持不变.)

public class MyLegacyClass {

  private static Strategy strategy = new JNDIStrategy();

  public static SomeLegacyClass doSomeLegacyStuff(SomeOtherLegacyClass legacyObj) {
    // legacy logic
    SomeLegacyClass result = strategy.doSomeStuff(legacyObj);
    // more legacy logic
    return result;
  }

  static void setStrategy(Strategy strategy){
    MyLegacyClass.strategy = strategy;
  }

}

interface Strategy{
  public SomeLegacyClass doSomeStuff(SomeOtherLegacyClass legacyObj);
}

class JNDIStrategy implements Strategy {
  private static final String jndiName = "java:comp/env/jdbc/LegacyDataSource";

  public SomeLegacyClass doSomeStuff(SomeOtherLegacyClass legacyObj) {
    // do stuff using jndiName
  }
}

...和JUnit测试.我不是必须进行这种设置/拆卸维护的忠实粉丝,但这是一个基于静态方法(或Singletons)的API的不幸副作用.我做喜欢这个测试是它不使用JNDI -这是很好的,因为(a)它会跑得快,和(b)单元测试应该只无论如何测试在doSomeLegacyStuff()方法中的业务逻辑,而不是测试实际数据来源.(顺便说一句,这假设测试类与MyLegacyClass在同一个包中.)

public class MyLegacyClassTest extends TestCase {

  private MockStrategy mockStrategy = new MockStrategy();

  protected void setUp() throws Exception {
    MyLegacyClass.setStrategy(mockStrategy);
  }

  protected void tearDown() throws Exception {
    // TODO, reset original strategy on MyLegacyClass...
  }

  public void testDoSomeLegacyStuff() {
    MyLegacyClass.doSomeLegacyStuff(..);
    assertTrue(..);
  }

  static class MockStrategy implements Strategy{

    public SomeLegacyClass doSomeStuff(SomeOtherLegacyClass legacyObj) {
      // mock behavior however you want, record state however
      // you'd like for test asserts.  Good frameworks like Mockito exist
      // to help create mocks
    }
  }
}