Java – JUnit: how to avoid “no runnable methods” in test utils classes

antjavajunittesting

I have switched to JUnit4.4 from JUnit3.8. I run my tests using ant, all my tests run successfully but test utility classes fail with "No runnable methods" error. The pattern I am using is to include all classes with name *Test* under test folder.

I understand that the runner can't find any method annotated with @Test attribute. But they don't contain such annotation because these classes are not tests.
Surprisingly when running these tests in eclipse, it doesn't complain about these classes.

In JUnit3.8 it wasn't a problem at all since these utility classes didn't extend TestCase so the runner didn't try to execute them.

I know I can exclude these specific classes in the junit target in ant script. But I don't want to change the build file upon every new utility class I add. I can also rename the classes (but giving good names to classes was always my weakest talent 🙂 )

Is there any elegant solution for this problem?

Best Answer

Annotate your util classes with @Ignore. This will cause JUnit not to try and run them as tests.

Related Solutions

Java – How to test a class that has private methods, fields or inner classes

Update:

Some 10 years later perhaps the best way to test a private method, or any inaccessible member, is via @Jailbreak from the Manifold framework.
@Jailbreak Foo foo = new Foo();
// Direct, *type-safe* access to *all* foo's members
foo.privateMethod(x, y, z);
foo.privateField = value;
This way your code remains type-safe and readable. No design compromises, no overexposing methods and fields for the sake of tests.

If you have somewhat of a legacy Java application, and you're not allowed to change the visibility of your methods, the best way to test private methods is to use reflection.

Internally we're using helpers to get/set private and private static variables as well as invoke private and private static methods. The following patterns will let you do pretty much anything related to the private methods and fields. Of course, you can't change private static final variables through reflection.

Method method = TargetClass.getDeclaredMethod(methodName, argClasses);
method.setAccessible(true);
return method.invoke(targetObject, argObjects);

And for fields:

Field field = TargetClass.getDeclaredField(fieldName);
field.setAccessible(true);
field.set(object, value);

Notes:
1. TargetClass.getDeclaredMethod(methodName, argClasses) lets you look into private methods. The same thing applies for getDeclaredField.
2. The setAccessible(true) is required to play around with privates.

Java – How to assert that a certain exception is thrown in JUnit 4 tests

It depends on the JUnit version and what assert libraries you use.

For JUnit5 and 4.13 see answer https://stackoverflow.com/a/2935935/2986984
If you use assertJ or google-truth, see answer https://stackoverflow.com/a/41019785/2986984

The original answer for JUnit <= 4.12 was:

@Test(expected = IndexOutOfBoundsException.class)
public void testIndexOutOfBoundsException() {

    ArrayList emptyList = new ArrayList();
    Object o = emptyList.get(0);

}

Though answer https://stackoverflow.com/a/31826781/2986984 has more options for JUnit <= 4.12.

Reference :

JUnit Test-FAQ

Best Answer

Related Solutions

Java – How to test a class that has private methods, fields or inner classes

Java – How to assert that a certain exception is thrown in JUnit 4 tests

Related Topic