How to generate random text from regex to fill an excel cell

Im creating a large amount of excel test files with different values in many columns.

These files are going to be imported into a database later using other unkown tool, so I just have to prepare only these files filled with valid data.

Each file has different columns, so different ranges of valid characters are necessary per column.

What would I want to do?

Use a Formula witch receive a regex and generate/and fill the cell with a random string based on that regex and if possible specify how many characters the string should be.

Can someone guide me in the creation of a macro to accomplish this purpose or suggest me a plugin to facilitate this work?