private void assertVerify(ConfigDefinition def, String id, String val, Class<?> expectedException) {
        try {
            def.verify(id, val);
        } catch (Exception e) {
            if (!(e.getClass().isAssignableFrom(expectedException))) {
                throw e;
            }
        }
    }
Unit tests for ConfigDefinition.

@author hmusum
config/src/test/java/com/yahoo/vespa/config/ConfigDefinitionTest.java