This kata doesn't satisfy basic kata requirements: spec is still unclear, test code is riddled with basic technical errors, only 7 fixed tests, and no random tests.

Kata author really should have a look at the kata authoring guideline.

Expected and actual values are flipped in the test assertion messages:

expected 'Idle\nInvalid floor number: 6\n' to equal ''

chai.config.truncateThreshold = 0; is also missing in test code, which truncates inputs in assertion messages:

expected 'Idle\nPressed button in elevator to g…' to equal 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx…'

Please describe elevator behavior more eplicitly. For example:

• Stopping to open doors takes 1 step
• After calling elevator, the elevator starts moving immediately (after 0 steps)
• The order in which events should be logged each step (button presses before moving, ...)

This way you don't have to resort to the test cases to find this out.

In the first example result:

Idle
Pressed button in elevator to go UP to 3 floor
Going up: 0.5
Going up: 1
Pressed button DOWN on 2 floor (then to -1)
Going up: 1.5
Going up: 2
...

Why is the Pressed button DOWN on 2 floor (then to -1) written after 2 steps? Is it because it reads the null as a move and one move = 2 steps / 1 floor?

should add character limit (2000 should be fine) to guard against hardcoding.

Is there an actual need for the steps parameter? The result always terminates either way.

For n <= 0 return empty string. But solutions that only check for n == 0 can pass easily in JS && Ruby at least