Two of the excruciatingly long tests seem to be broken. Debug code:

puts "Initial ints length is: #{ints.length}"
if ints.length < 10
puts ints
end

shows that the "Two Million Numbers With Pair At End: Should terminate with a valid pair output" and "Two Million Numbers With Pair At Start: Should terminate with a valid pair output" tests are only passing in 2 and 1 element arrays respectively, but are expecting a match (that isn't present in the arrays).