assertTrue(isPositive.apply(100));
        assertFalse(isPositive.apply(0));
        assertFalse(isPositive.apply(-1));
        assertFalse(isPositive.apply(null));
    }

    public void test_apply_object() {
        BooleanFunction<Object> isNotNull = obj -> obj != null;

        assertTrue(isNotNull.apply("test"));
        assertTrue(isNotNull.apply(123));
        assertTrue(isNotNull.apply(new Object()));