This is actually an issue, and there are several already raised about tests being insufficient in most (if not all languages). Your suggestion is not bad per se, but it's part of a much larger issue in this kata that is already pointed out, I would suggest you to close it (we could open tens of other similar suggestions, without fixing the root of the problem).

all tests done in this kata only test the first block, not all the 9 blocks;
please add more cases to the test so it checks other blocks

for one of my submitted solutions, this case returns true, and it should return false

[
[2, 3, 1, 5, 6, 4, 8, 9, 7],

[4, 5, 6, 7, 8, 9, 1, 2, 3],

[8, 9, 7, 2, 3, 1, 5, 6, 4],

[3, 1, 2, 6, 4, 5, 9, 7, 8],

[1, 2, 3, 4, 5, 6, 7, 8, 9],

[5, 6, 4, 8, 9, 7, 2, 3, 1],

[6, 4, 5, 9, 7, 8, 3, 1, 2],

[7, 8, 9, 1, 2, 3, 4, 5, 6],

[9, 7, 8, 3, 1, 2, 6, 4, 5]]

omgggggggggggggggggggggggggggggggggggggggg