Python fork which adds the check for user solution on if it's a valid Regex expression and catches the exception on such.
UPD: also plainified all random test inputs to show so that it wouldn't cause a HTML hell in a frame

Input range needs to be specified. (Because apparently the input only goes up to 500, which makes this kata extremely easy)

Instructions mention it should return "Invalid date" but the tests are testing for "Invalid date!" (in those cases)

The approximation formula could use extra parentheses, to reduce ambiguity.
Currently, it says "π * (3/2(a+b) - sqrt(ab))"
Perhaps it should say "π * ((3/2)(a+b) - sqrt(ab))"

Just to be clear that it isn't 3/(2(a+b))

Python, possibly other languages: tests miss sanity checks on values returned by user solution and crash badly when an unexpected value (not a pattern, or not a valid pattern) is returned.

JS: No random test

As pointed out below, there're no tests with repeated keys.

Ruby 3.0 should be enabled.

Duplicate of all the prime testing katas.

There are no mentions anywhere that input validation is required.

Hello, there are a couple hacks that only check for presence of the three expected groups and leading/trailing commas, but don't check for redundancy.
Adding a few tests like name:Tomek,age:30,skill:PHP,name:Kemot would change that.

A very good kata nonetheless and Gosh, the absence of conditionals in JS RegExps makes it so fastidious!

Tests are still quite weak and doesn't test the requirement strictly.

Also, where are the random tests?

Nicely done. A couple of minor ideas for improvement:

• Add a Regex101 link to the description to get people started (a lot people use that to debug/develop regular expressions). Such as: https://regex101.com/r/uOwtDQ/1
• Add useful failure messages to all tests, so that people can more quickly debug their code.