The example in the description is not very clear, it is better to write it somehow, separating the first elements like this:

S1; (S1, S2); 9

S2; (S1, S3); 10

S3; (S4, S3); 8

S4; (S4, S1); 0

Ruby 3.0 should be enabled, read this to learn how to do it

Please organize the structure of test fixture as following (although it has been mentioned in the attached link, I'm repeated here again)

describe "<This message should describe the categories of test groups inside this block>" do
  it "<A short message describing this test group>" do
    expect(...).to eq(...) #Assertions
    #Or Test.assert_equals(user_response, reference_response)
  end
end

What we want to do is take in a list of numbers between 0-31

There are negative numbers in the tests.
Or it's "what we want to do" rather than what we really do...

A cursory search reveals at least 3 duplicates:

• https://www.codewars.com/kata/convert-integer-to-binary
• https://www.codewars.com/kata/convert-to-binary/javascript
• https://www.codewars.com/kata/convert-natural-number-to-its-binary-representation/javascript

At least do a bare minimum search before throwing another onto the pile.

The kata should also mention that we need to handle duplicates.

It isn't mentioned anywhere except sometimes appearing in random tests.