Added Elisp version of the kata

elisp/gilded-rose-test.el

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+(require 'ert)
+(require 'gilded-rose)
+
+(ert-deftest check-name-of-item ()
+  "Test that item is called sweets. This test should fail!"
+  (let ((sweets (make-item "sweets" 5 5)))
+    (should (string= (item-name sweets) "You should change this"))))
+
+(ert-run-tests-interactively t)

elisp/gilded-rose.el

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+(defun make-item (name sell-in quality)
+  "Create an item with NAME, SELL-IN, and QUALITY."
+  (list :name name :sell-in sell-in :quality quality))
+
+(defun item-name (item)
+  "Return the name of ITEM."
+  (plist-get item :name))
+
+(defun item-sell-in (item)
+  "Return the sell-in value of ITEM."
+  (plist-get item :sell-in))
+
+(defun item-quality (item)
+  "Return the quality of ITEM."
+  (plist-get item :quality))
+
+(defun update-quality (item)
+  "Update the quality of the ITEM according to the Gilded Rose rules."
+  (let ((quality (item-quality item))
+        (sell-in (item-sell-in item)))
+    (cond
+     ;; Aged Brie
+     ((string= (item-name item) "Aged Brie")
+      (setf (nth 2 item) (min 50 (1+ quality))))
+
+     ;; Backstage passes
+     ((string= (item-name item) "Backstage passes")
+      (cond
+       ((> sell-in 10) (setf (nth 2 item) quality))
+       ((and (<= sell-in 10) (> sell-in 5)) (setf (nth 2 item) (min 50 (+ quality 2))))
+       ((and (<= sell-in 5) (> sell-in 0)) (setf (nth 2 item) (min 50 (+ quality 3))))
+       (t (setf (nth 2 item) 0))))
+
+     ;; Sulfuras
+     ((string= (item-name item) "Sulfuras")
+      (setf (nth 2 item) quality))
+
+(provide 'gilded-rose)

elisp/readme.org

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+* Gilded Rose
+Gilded Rose kata in Elisp!
+
+* Structure
+~gilded-rose.el~ contains source code. ~gilded-rose-test.el~ uses [[https://www.gnu.org/software/emacs/manual/html_mono/ert.html][ert]] to run tests
+
+* Running tests
+- Use the command ~eval-buffer~ on ~gilded-rose.el~
+- Use the command ~eval-buffer~ on ~gilded-rose-test.el~
+- Test can be run interactively using the command ~ert~ or with ~(ert-run-tests-interactively t)~