Testing Exceptions Using Java Reflection Junit4

Question

I have a function that returns an exception, and I write unit test for it in Junit4. The problem is that reflect.invoke always ends the exception in the InvocationTargetException and therefore cannot check the exception using the ExpectedException class.

public class Hello {
private void printHello(String msg) {
    if ("hello".equals(msg)) {
        System.out.println("Hello");
    }
        else throw new HeaderException();
    }
}

Test:

@Rule
public ExpectedException expectedEx = ExpectedException.none();
@Test
public void testPrint() throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
    expectedEx.expect(HeaderException.class);

    Method method = Hello.class.getDeclaredMethod("printHello", String.class);
    method.setAccessible(true);
    method.invoke(Hello.class,"random");

}

Conclusion:

    java.lang.AssertionError: 
Expected: an instance of com.locationguru.CSF.exception.HeaderException
     got: <java.lang.reflect.InvocationTargetException>
 <Click to see difference>

    at org.junit.Assert.assertThat(Assert.java:780)
    at org.junit.Assert.assertThat(Assert.java:738)
    at org.junit.rules.ExpectedException$ExpectedExceptionStatement.evaluate(ExpectedException.java:114)
    at org.junit.rules.RunRules.evaluate(RunRules.java:18)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:78)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:212)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:68)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)

Answer 1

One way to do this may be to repeat the expected error, but is it recommended

 try
    {
        method.invoke(Hello.class, "random");
    }
    catch (InvocationTargetException e)
    {
        throw e.getTargetException();
    }