Ruby與Rspec - 此測試如何通過？

Question

此測試通過驗證，但是如何？

#Rspec 
it "handles a case with an answer > 1 distance to the left" do 
    nearest_larger([8,2,4,3], 2).should == 0 
end 

#Function 
def nearest_larger(arr, idx) 
    diff = 1 

    loop do 
    left = idx - diff 
    right = idx + diff 

    if (left >= 0) && (arr[left] > arr[idx]) 
     return left 
    elsif (right < arr.length) && (arr[right] > arr[idx]) 
     return right 
    elsif (left > 0) && (right >= arr.length) 
     return nil 
    end 

    diff += 1 
    end 
end 

我正在通過一些ruby的例子，我不明白這個測試如何通過驗證。 0從哪裏返回？

Answer 1

當idx是2和diff爲2（即，在第二次的循環），left是2 - 2 = 0，和arr[0] == 8，比arr[2] == 4更大。該函數然後返回left，該值爲零。