Will be better if you just give better names for your variables.

Solution is not running.

Don't show the entry string when failed. How to understand the bug? ====>
Test Results:
RunesTest
EdgeCase
Test Failed
Expected: 8
But was: 0
Completed in 68.4420ms
testAddition
Test Failed
Expected: 0
But was: -1
Completed in 0.9640ms
testMultiplication
Test Failed
Expected: 0
But was: -1
Completed in 0.7850ms
testRandom
Test Failed
Expected: 3
But was: -1
Completed in 1.3650ms
testSubtrastion
Test Failed
Expected: 0
But was: -1
Completed in 0.7180ms
Completed in 79.3880ms

This solution doesn't work when other letters are used. Like {"n","s","n","s","n","s","n","s","a","a"}.

Not high performance. It needs go all chars allways.