Expression { @Override public String toString() { return (language == null ? "DEFAULT" : language) + ":" + expression; } Expression(String expression, String language);  Expression(String expression);  Expression(Expression toCopy); static Expression createExpressionFromDescribedExpression(String describedExpression); static Expression createExpression(String expression, String language); String getExpression(); String getLanguage(); @Override boolean equals(Object obj); @Override int hashCode(); @Override String toString();  }
@Test public void testToString() { Expression expression = new Expression("hello", "there"); assertEquals("there:hello", expression.toString()); expression = new Expression("hello"); assertEquals("DEFAULT:hello", expression.toString()); }