port GildedRose Java/Ruby to R language, add a RUnit test stub

R/gilded_rose.R

@@ -0,0 +1,56 @@
+source('item.R')
+
+update_quality <- function(items) {
+  lapply(items, 
+    function(item) {
+      
+      if (item$name != "Aged Brie" && item$name != "Backstage passes to a TAFKAL80ETC concert") {
+        if (item$quality > 0) {
+          if (item$name != "Sulfuras, Hand of Ragnaros") {
+            item$quality <- item$quality - 1
+          }
+        }
+      } else {
+        if (item$quality < 50) {
+          item$quality <- item$quality + 1
+          if (item$name == "Backstage passes to a TAFKAL80ETC concert") {
+            if (item$sell_in < 11) {
+              if (item$quality < 50) {
+                item$quality = item$quality + 1
+              }
+            }
+            if (item$sell_in < 6) {
+              if (item$quality < 50) {
+                item$quality = item$quality + 1
+              }
+            }
+          }
+        }
+      }
+      
+      if (item$name != "Sulfuras, Hand of Ragnaros") {
+        item$sell_in <- item$sell_in - 1
+      }
+      
+      if (item$sell_in < 0) {
+        if (item$name != "Aged Brie") {
+          if (item$name != "Backstage passes to a TAFKAL80ETC concert") {
+            if (item$quality > 0) {
+              if (item$name != "Sulfuras, Hand of Ragnaros") {
+                item$quality <- item$quality - 1
+              }
+            }
+          } else {
+            item$quality <- item$quality - item$quality
+          }
+        } else {
+          if (item$quality < 50) {
+            item$quality <- item$quality + 1
+          }
+        }
+      }
+      
+      item
+    } 
+  ) 
+}