How would you assert an array (or a list) is sorte...

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[louiscad]

How would you assert an array (or a list) is sorted by a given selector/property its elements have? My use case is enforcing the order of an enum based on one of its properties (its only property actually).

EDIT: found a solution:

enum ThatEnum(val thatProperty: Float) {
    FirstEntry(thatProperty = 10),
    AnotherEntry(thatProperty = 20),
    LastEntry(thatProperty = Float.POSITIVE_INFINITY);

    companion object {
        init {
            check(values().contentEquals(values().apply { sortBy { it.thatProperty } }))
        }
    }
}

That requires to companion object to be accessed for the check to execute, which is fine in my case since I use it to get instances of the enum early.

[Ashish Kumar Joy]

Are you talking about checking that in a test or in source code?

[louiscad]

In source code so it stays contextual

[pedro]

It probably doesn’t matter but you could save some GC/memory by using fold instead. (Check that the property monotonically increases.)

[louiscad]

That's a good idea @pedro!

[Matteo Mirk]

Your requirement is being able to check at runtime that these constants and future additions will remain sorted according to a property, right?

[louiscad]

Here's what I ended up using, with fold.

Proximity_kt.kt