CODEWITHSUNDEEP
javajunit
Ken
Ken

Reputation: 343

JUnit testing can't find the method that I want to test

Below is the (incomplete) piece of code containing the method "IntRelation" that I would like to test on whether it throws exceptions or not.

public abstract class IntRelation {

    public IntRelation(final int n) throws IllegalArgumentException {
        if (n < 0) {
            throw new IllegalArgumentException ("Parameter in precondition violated.");
        }
    }
}

Below is the (incomplete) piece of code containing the test case for the "IntRelation" method.

public abstract class IntRelationTestCases {

    protected IntRelation instance;

    @Test
    public void testException0() {
        Class expected = IllegalArgumentException.class;
        instance.IntRelation(-1);
    }
}

The problem I am encountering is that in the second piece of code, NetBeans/JUnit says that it cannot find the method "IntRelation". What am I doing wrong?

Upvotes: 0

Views: 3571

Answers (1)

ChiefTwoPencils
ChiefTwoPencils

Reputation: 13930

That's true. It's because you're invoking a constructor like it's a method; don't do that.

I suppose what you wanted to do was instance = new IntRelation(...);

or you meant that to actually be a method in which case you haven't defined it properly due to missing a return type.

public void IntRelation(...) should do it in that regard.

But then you'd have an issue of an un-instantiated instance which should lead you to a NullPointerException.

If you want to have some data set up to test it's good practice to use annotations to get things ready for testing.

Example:

@Before
public void setUp() {
    // Since your class is abstract you can do it like this
    // to get an anonymous class you can test that non-abstract
    // method with...
    instance = new IntRelation() { };
}

then call it as usual from the test testing that unit.

@Test
public void testException0() {
    ...
    instance.IntRelation(-1);
}

I would say, though, naming a method identical to its class name seems potentially confusing. Plus, it's against Java naming conventions to name a method with leading caps; first letter should be lower-case and the rest should camel. For example, thisIsTheCorrectWay(...).

Upvotes: 5

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