table it_generates_equivalent_table_markdown lost alignments

[OceanBelongsToMe]

in test the method it_generates_equivalent_table_markdown:

let original_table_markdown = indoc!(
"|1 |2 |3 |4 |5 |6 |7 |
| :---------------: | :--------------------: | :------: | :------: | :-----------: | :--------: | :------: |
| col 3 is | col 3 is | col 3 is | col 3 is | col 3 is | col 3 is | col 3 is |
| col 3 is | col 3 is | col 3 is | col 3 is | col 3 is | col 3 is | col 3 is |
| col 3 is | col 3 is | col 3 is | col 3 is | col 3 is | col 3 is | col 3 is |
| col 3 is | col 3 is | col 3 is | col 3 is | col 3 is | col 3 is | col 3 is |
| col 3 is | col 3 is | col 3 is | col 3 is | col 3 is | col 3 is | col 3 is |
| col 3 is | col 3 is | col 3 is | col 3 is | col 3 is | col 3 is | |"
);
will remove '-',only ':' exists,like this:

|1|2|3|4|5|6|7|\n|:|:|:|:|:|:|:|\n|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|\n|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|\n|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|\n|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|\n|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|\n|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is|col 3 is||

[Byron]

Could you express this in a test-case so that the expectation becomes clear? Doing so would also be a first step towards a fix.
Thanks