From fbb8b8ad61ee99998ec7b8e3a8873a8d8950e943 Mon Sep 17 00:00:00 2001
From: Yudai Tanaka <ytnk531@gmail.com>
Date: Fri, 7 May 2021 07:40:35 +0900
Subject: [PATCH] Add error cases.

---
 ruby/gilded_rose_spec.rb | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/ruby/gilded_rose_spec.rb b/ruby/gilded_rose_spec.rb
index ded3c5cd..7bd8dac3 100644
--- a/ruby/gilded_rose_spec.rb
+++ b/ruby/gilded_rose_spec.rb
@@ -2,8 +2,12 @@ require File.join(File.dirname(__FILE__), "gilded_rose")
 
 describe GildedRose do
   describe "#update_quality" do
-    def updated_items(items)
+    def update_items(items)
       GildedRose.new(items).update_quality
+    end
+
+    def updated_items(items)
+      update_items(items)
       items
     end
 
@@ -201,5 +205,13 @@ describe GildedRose do
         expect(items[0].sell_in).to eq(-1)
       end
     end
+
+    context "when process nil" do
+      it { expect { update_items(nil) }.to raise_error }
+    end
+
+    context "when process an array which contains nil" do
+      it { expect { update_items([nil]) }.to raise_error }
+    end
   end
 end