the description does not specify which group of consecutive zeroes to compress when there are several groups tied for the longest sequence

RFC 5952 does say:

When the length of the consecutive 16-bit 0 fields
are equal (i.e., 2001:db8:0:0:1:0:0:1), the first sequence of zero
bits MUST be shortened. For example, 2001:db8::1:0:0:1 is [the] correct
representation.

Description should be language-agnostic

Missing sample and fixed tests for consecutive colons of longer than 3, i.e,

• 0101:::::::

• :::::0:1:0:1

• 0A0B:0C0d::::28c1:1:2

etc...

The case with single group of zeroes appearing in the middle (instead of the ends) of a IPv6 address is missing in the fixed tests (when everything else is included in the fixed tests). It's only in the random tests.

The kata is stuck at Node 8.

IPv4 address component in IPv6 isn't tested.

Essentially a duplicate: https://www.codewars.com/kata/5980d4e258a9f5891e000062 and no Random tests.

input:              1:1:0:0:1::1
"conracted" from:   1:1:0:0:1:0:0:1
valid contraction:  1:1::1:0:0:1

The rule that the first longest group must be contracted is ignored here, hence this input should be considered as invalid, and yet the tests consider it to be correct. Either this case should be removed or it should be changed to expect false.

random tests?