Merge pull request #251 from verdammelt/two-fer

Add two-fer exercise.

Author: verdammelt

config.json

@@ -18,6 +18,18 @@
         "strings"
       ]
     },
+    {
+      "slug": "two-fer",
+      "uuid": "b80ab7d9-6152-4351-b405-07c2fb071962",
+      "core": true,
+      "unlocked_by": null,
+      "difficulty": 1,
+      "topics": [
+        "strings",
+        "optional_values",
+        "text_formatting"
+      ]
+    },
     {
       "slug": "luhn",
       "uuid": "7cc9d827-b08e-437d-826e-244f220feca0",

exercises/two-fer/README.md

@@ -0,0 +1,80 @@
+# Two Fer
+
+`Two-fer` or `2-fer` is short for two for one. One for you and one for me.
+
+Given a name, return a string with the message:
+
+```text
+One for X, one for me.
+```
+
+Where X is the given name.
+
+However, if the name is missing, return the string:
+
+```text
+One for you, one for me.
+```
+
+Here are some examples:
+
+|Name    |String to return 
+|:-------|:------------------
+|Alice   |One for Alice, one for me. 
+|Bob     |One for Bob, one for me.
+|        |One for you, one for me.
+|Zaphod  |One for Zaphod, one for me.
+
+## Setup
+
+Check out [Installing Common
+Lisp](https://exercism.io/tracks/common-lisp/installation) for
+instructions to get started or take a look at the guides available in
+the [track's side bar](https://exercism.io/my/tracks/common-lisp).
+
+## Formatting
+
+While Common Lisp doesn't care about indentation and layout of code,
+nor whether you use spaces or tabs, this is an important consideration
+for submissions to exercism.io. Excercism.io's code widget cannot
+handle mixing of tab and space characters well so using only spaces is recommended to make
+the code more readable to the human reviewers. Please review your
+editors settings on how to accomplish this. Below are instructions for
+popular editors for Common Lisp.
+
+### VIM
+
+Use the following commands to ensure VIM uses only spaces for
+indentation:
+
+```vimscript
+:set tabstop=2
+:set shiftwidth=2
+:set expandtab
+```
+
+(or as a oneliner `:set tabstop=2 shiftwidth=2 expandtab`). This can
+be added to your `~/.vimrc` file to use it all the time.
+
+### Emacs
+
+Emacs is very well suited for editing Common Lisp and has many
+powerful add-on packages available. The only thing that one needs to
+do with a stock emacs to make it work well with exercism.io is to
+evaluate the following code:
+
+`(setq-default indent-tabs-mode nil)`
+
+This can be placed in your `~/.emacs` (or `~/.emacs.d/init.el`) in
+order to have it set whenever Emacs is launched.
+
+One suggested add-on for Emacs and Common Lisp is
+[SLIME](https://github.com/slime/slime) which offers tight integration
+with the REPL; making iterative coding and testing very easy.
+
+## Source
+
+[https://github.com/exercism/problem-specifications/issues/757](https://github.com/exercism/problem-specifications/issues/757)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

exercises/two-fer/example.lisp

@@ -0,0 +1,8 @@
+(in-package #:cl-user)
+(defpackage #:two-fer
+  (:use #:cl)
+  (:export #:twofer))
+(in-package #:two-fer)
+
+(defun twofer (name)
+  (format nil "One for ~a, one for me." (or name "you")))

exercises/two-fer/two-fer-test.lisp

@@ -0,0 +1,34 @@
+;;;
+;;; two-fer v1.2.0
+;;;
+(ql:quickload "lisp-unit")
+#-xlisp-test (load "two-fer")
+
+(defpackage #:two-fer-test
+  (:use #:common-lisp #:lisp-unit))
+(in-package #:two-fer-test)
+
+(define-test
+  no-name-given
+  (assert-equal
+    "One for you, one for me."
+    (two-fer:twofer nil)))
+
+
+(define-test
+  a-name-given
+  (assert-equal
+    "One for Alice, one for me."
+    (two-fer:twofer "Alice")))
+
+
+(define-test
+  another-name-given
+  (assert-equal
+    "One for Bob, one for me."
+    (two-fer:twofer "Bob")))
+
+#-xlisp-test
+(let ((*print-errors* t)
+      (*print-failures* t))
+  (run-tests :all))

exercises/two-fer/two-fer.lisp

@@ -0,0 +1,7 @@
+(in-package #:cl-user)
+(defpackage #:two-fer
+  (:use #:cl)
+  (:export #:twofer))
+(in-package #:two-fer)
+
+(defun twofer (name))