Coverage for private constructor junit/emma

Question

how can i write a @test class for a private constructor. i want to cover it with emma tool too.

public final class Product {

    private Product() {

    }
}

can someone suggest a simple way?

thanks.

score 9 · Accepted Answer · answered Oct 31 '13 at 06:21

The best way to test private methods is to use Reflection.

There are many ways, but I would simple do this;

@Test
    public void testConstructorIsPrivate() throws Exception {
      Constructor constructor = Product.class.getDeclaredConstructor();
      assertTrue(Modifier.isPrivate(constructor.getModifiers()));
      constructor.setAccessible(true);
      constructor.newInstance();
    }

This will cover the constructor when running the coverage tool emma.

score 7 · Answer 2 · answered Oct 31 '13 at 06:28

7

I don't think you should test private constructors, since they are part of the implementation. Write tests only for API methods with well-defined contracts.

answered Oct 31 '13 at 06:28

siledh

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1

This is a good point. I would agree that its usually (though not always) true. . I've found a few situations where I wanted to test a private method or constructor, and couldn't get at it via the public API for one reason or another. – Jasper Blues Oct 31 '13 at 06:57
1

The reason unfortunately is code test coverage scanners, e.g., Sonar, Emma. – JeeBee Dec 17 '15 at 16:48

Coverage for private constructor junit/emma

2 Answers2