public void checkCollation(

      String expression,

      String expectedCollationName,

      SqlCollation.Coercibility expectedCoercibility) {

    for (String sql : buildQueries(expression)) {

      RelDataType actualType = getColumnType(sql);

      SqlCollation collation = actualType.getCollation();



      assertEquals(

          expectedCollationName, collation.getCollationName());

      assertEquals(expectedCoercibility, collation.getCoercibility());

    }

  }