You haven't written anything for your kata beyond the title. Please actually finish writing your kata before publishing to beta.

Random tests are needed.

The unit of x and phase is not mentioned. They're apparently different (x is in angular wavenumber, phase is in radians)

a sequence of strings, representing all absolute paths of the given length leading to the directory pointed by the given canonical path

Tests strictly requires return type to be a set, rather than a sequence (which would be a iterable). A set is also not a sequence, so the output as specified by the description is misleading.

Looks good now

This is supposed to be a performance kata but author solution (aka reference solution) is inadequate: it is O(log(n)*k) even though a relatively simple O(log(n)*log(k)) solution exists, as demonstrated by some solutions. The random tests are slowed by a lot by the reference solution as a result.

Please replace the reference solution with an algorithm with optimal time complexity and bump up the range of k to make sure this is enforced.

Please fix the sample tests:

File "/workspace/default/tests.py", line 5
    def fixed_tests:
                   ^
SyntaxError: expected '('

There should be specifically a set of random tests that probe solutions against these overlapping cases.

that's why there are also randomized tests in the suite, so they can't be hardcoded

Yes, but if the random tests can be passed by a simplier, incorrect algorithm then the random tests are too weak, which is the issue here.

Notably, I can still pass the entire suite with my incorrect solution just by hardcoding for the 2 additional fixed tests.

You may assume that a solution for x exists and is unique.

Why x needs to be unique? Yes, every solution except mine can't handle non-unique solutions (e.g a = 6, b = 24), but then you're arbitrarily limiting input a to be odd, and it doesn't add anything to a correct solution since the test accepts all correct xs anyway (it only checks a * x == b).

run_test_case is from preloaded, not solution. solution implicitly imports preloaded, but importing it from solution means user can supply their own implementation which overwrites the entire testing mechanism.

Actual tests aren't random. It's testing a fixed, linear sequence of numbers.