How to test a constructor will throw an illegal state exception?

Question

I have a utility class with a private constructor that throws an Illegal state exception and I want to test that it does this.

I've tried a test where I implement the constructor, but since the constructor is private it can't be accessed outside of the class. So is it just pointless to test the constructor?

from the class

 private UtilityClass(){
        throw new IllegalStateException("Utility Class");
    }

from the test class

private UtilityClass = utilityClass;
    @Test(expected = IllegalStateException.class)
    public void constructorTest(){
        utilityClass = new UtilityClass();
    }

Do you have any static method to get the instance from the outside? — Maciej Kowalski, Jul 22 '19 at 17:48
you make it private so that no one can access it, and also you might be using that in one of the method or constructor. so just test that method which should be fine — Ryuzaki L, Jul 22 '19 at 17:55
I agree. You should test a methods directly - if they can be accessed *public*. Your constructor is *private*, so if it is used by *public* methods - then you should test these methods to detect exception. — Mateusz Palichleb, Jul 22 '19 at 18:17
change the code to use an interface instead of a class. then no more constructor, nothing to test. — Nathan Hughes, Jul 22 '19 at 18:34
I guees I'll just supress the warning and take out the constructor — nolanite1, Jul 29 '19 at 19:33

score 0 · Answer 1 · answered Jul 22 '19 at 18:30

0

You can test that a constructor throws an exception by defining a public constructor and then writing appropriate test code. If you have a private constructor (or private method), you cannot directly test it.

answered Jul 22 '19 at 18:30

Kaan

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How to test a constructor will throw an illegal state exception?

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