Statement Invalid Error while running Rails test

I have a model friend_request and wrote unit tests for this model. While running tests, I get this error :

ActiveRecord::StatementInvalid: PG::InFailedSqlTransaction: ERROR:  current transaction is aborted, commands ignored until end of transaction block                                       
:SELECT a.attname, format_type(a.atttypid, a.atttypmod),
                 pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
            FROM pg_attribute a LEFT JOIN pg_attrdef d
              ON a.attrelid = d.adrelid AND a.attnum = d.adnum
           WHERE a.attrelid = '"friend_requests"'::regclass
             AND a.attnum > 0 AND NOT a.attisdropped
           ORDER BY a.attnum

Any idea what is wrong?