String exp = "unit test";
EvalFunc<String> sConcat = new StringConcat();
Tuple ts = TupleFactory.getInstance().newTuple(2);
ts.set(0, s1);
ts.set(1, s2);
String res = sConcat.exec(ts);
msg = "[Testing StringConcat on input type: String]";
assertTrue(msg, res.equals(exp));
}