1. I think this kata needs random tests, but not randomly selected static tests.
2. Test debug messages are not readable. It might be better to display airport indices, but not a complete string representation of the airport.
3. Why did you mention caching distances between airports? This is not necessary for current test cases.

Hello, nice kata !

I get some weird results sometimes though.
I'll name airports by their index in the given list.

Sometime, I find a route shorter that your solution but with an extra stop.
For example,
range : 6883
my route is : 91 -> 86 -> 163
distance : 6596 + 269 = 6865

expected route is : 91 -> 163
distance : 6866

I have manually checked, and the distanceTo method give these results.
Do you know how this could happen ?

I still passed the kata cause this does not always happen depending on random tests...