Add tests for `--output` CLI flag
Add tests for `--output` CLI flag

eush77/remark,ulrikaugustsson/mdast,chcokr/mdast,yukkurisinai/mdast,ulrikaugustsson/mdast,eush77/remark,chcokr/mdast,yukkurisinai/mdast,tanzania82/remarks,wooorm/remark