[collections] Does WrappedBloomFilterTest make sense?

[Gary Gregory]

The WrappedBloomFilterTest currently says [0][1] that a copy of a
WrappedBloomFilter is not a WrappedBloomFilter, which does not make sense
to me as non-SME.

Should the test be adjusted? It looks like the test is written in a
contrived way due to WrappedBloomFilter being abstract. I would make more
sense to me to have private static WrappedBloomFilter in the test and use
it, like this:

    private static class Fixture extends WrappedBloomFilter {

        public Fixture(BloomFilter wrapped) {
            super(wrapped);
        }

        @Override
        public WrappedBloomFilter copy() {
            return new Fixture(getWrapped());
        }

    }

    @Override
    protected WrappedBloomFilter createEmptyFilter(final Shape shape) {
        return new Fixture(new
DefaultBloomFilterTest.SparseDefaultBloomFilter(shape));
    }

    @ParameterizedTest
    @ValueSource(ints = {0, 1, 34})
    public void testCharacteristics(final int characteristics) {
        final Shape shape = getTestShape();
        final BloomFilter inner = new
DefaultBloomFilterTest.SparseDefaultBloomFilter(shape) {
            @Override
            public int characteristics() {
                return characteristics;
            }
        };
        final WrappedBloomFilter underTest = new Fixture(inner);
        assertEquals(characteristics, underTest.characteristics());
    }

WDYT?

Let's skip discussing the signature of the copy() method, I'll write a
separate email later about that.

TY,
Gary
[0]
https://github.com/apache/commons-collections/blob/730d972cdebb13dd3a896eb5b90ebc9e1f594d5b/src/test/java/org/apache/commons/collections4/bloomfilter/WrappedBloomFilterTest.java#L26-L56
[1] The above link in WrappedBloomFilterTest is:

    @Override
    protected WrappedBloomFilter createEmptyFilter(final Shape shape) {
        return new WrappedBloomFilter(new
DefaultBloomFilterTest.SparseDefaultBloomFilter(shape)) {
            @Override
            public BloomFilter copy() {
                final BloomFilter result = new
DefaultBloomFilterTest.SparseDefaultBloomFilter(shape);
                result.merge(getWrapped());
                return result;
            }
        };
    }

    @ParameterizedTest
    @ValueSource(ints = {0, 1, 34})
    public void testCharacteristics(final int characteristics) {
        final Shape shape = getTestShape();
        final BloomFilter inner = new
DefaultBloomFilterTest.SparseDefaultBloomFilter(shape) {
            @Override
            public int characteristics() {
                return characteristics;
            }
        };
        final WrappedBloomFilter underTest = new WrappedBloomFilter(inner) {
            @Override
            public BloomFilter copy() {
                final BloomFilter result = new
DefaultBloomFilterTest.SparseDefaultBloomFilter(shape);
                result.merge(getWrapped());
                return result;
            }
        };
        assertEquals(characteristics, underTest.characteristics());
    }