JUnit是常用单元测试工具,如果希望跳过某个测试类,一般在类上面添加@Ignore注解。实际情况下,经常遇到某些测试类在符合某些条件时需要运行、不符合时又不需要运行的情况,频繁加减@Ignore注解的话相当繁琐。有没有办法,能根据自己的配置文件,灵活决定是否运行某些测试类呢?
首先来分析一下JUnit源码(以4.10版本为例)。在org.junit.runner包下,有个JUnitCore.class,其中的main方法就是JUnit入口函数。经过runMainAndExit->runMain->run的多次调用,发现在run之中通过Request.classes方法构建了AllDefaultPossibilitiesBuilder对象,该对象用于选择RunnerBuilder,继而选择Runner执行测试用例。源码如下:
public static Request classes(Computer computer, Class<?>... classes) { try { AllDefaultPossibilitiesBuilder builder= new AllDefaultPossibilitiesBuilder(true); Runner suite= computer.getSuite(builder, classes); return runner(suite); } catch (InitializationError e) { throw new RuntimeException( "Bug in saff's brain: Suite constructor, called as above, should always complete"); } } |
在AllDefaultPossibilitiesBuilder中有个runnerForClass方法,就是该方法选择了RunnerBuilder,并通过调用RunnerBuilder的runnerForClass方法,最终决定了
Runner: @Override public Runner runnerForClass(Class<?> testClass) throws Throwable { List<RunnerBuilder> builders= Arrays.asList( ignoredBuilder(), annotatedBuilder(), suiteMethodBuilder(), junit3Builder(), junit4Builder()); for (RunnerBuilder each : builders) { Runner runner= each.safeRunnerForClass(testClass); if (runner != null) return runner; } return null; } |
从上述代码可以看出,正常情况下会选择JUnit4Builder,其源码如下:
public class JUnit4Builder extends RunnerBuilder { @Override public Runner runnerForClass(Class<?> testClass) throws Throwable { return new BlockJUnit4ClassRunner(testClass); } } |
而一旦对类添加了@Ignore注解,则会选择IgnoredBuilder,其源码如下:
public class IgnoredBuilder extends RunnerBuilder { @Override public Runner runnerForClass(Class<?> testClass) { if (testClass.getAnnotation(Ignore.class) != null) return new IgnoredClassRunner(testClass); return null; } } |
看到这里,我们大体可以认为,BlockJUnit4ClassRunner(testClass)会正常运行测试类,而IgnoredClassRunner(testClass)则会跳过运行测试类。因此,对于开始提出的问题,可以用如下方法解决:构建自己的Builder类,在其中的runnerForClass中根据配置决定是否运行测试类。