Add reverse-string to ruby exercises

config.json

@@ -1198,6 +1198,16 @@
       "topics": [
         "arrays"
       ]
+    },
+    {
+      "slug": "reverse-string",
+      "uuid": "64c64613-9dd9-461e-90ba-90f84e17e197",
+      "core": false,
+      "unlocked_by": null,
+      "difficulty": 1,
+      "topics": [
+        "strings"
+      ]
     }
   ]
 }

exercises/reverse-string/.meta/generator/reverse_string_case.rb

@@ -0,0 +1,9 @@
+require 'generator/exercise_case'
+
+class ReverseStringCase < Generator::ExerciseCase
+  def workload
+    [
+      "assert_equal #{expected.inspect}, ReverseString.reverse(#{value.inspect})"
+    ]
+  end
+end

exercises/reverse-string/.meta/hints.md

@@ -0,0 +1,3 @@
+# Hints
+
+The Ruby library is pretty extensive! Look through Ruby's built-in `String` methods and see if you can find something that will help you out with this exercise.

exercises/reverse-string/.meta/solutions/reverse_string.rb

@@ -0,0 +1,5 @@
+module ReverseString
+  def self.reverse(string)
+    string.reverse
+  end
+end

exercises/reverse-string/README.md

@@ -0,0 +1,42 @@
+# Reverse String
+
+Reverse a string
+
+For example:
+input: "cool"
+output: "looc"
+
+# Hints
+
+The Ruby library is pretty extensive! Look through Ruby's built-in `String` methods and see if you can find something that will help you out with this exercise.
+
+
+* * * *
+
+For installation and learning resources, refer to the
+[Ruby resources page](http://exercism.io/languages/ruby/resources).
+
+For running the tests provided, you will need the Minitest gem. Open a
+terminal window and run the following command to install minitest:
+
+    gem install minitest
+
+If you would like color output, you can `require 'minitest/pride'` in
+the test file, or note the alternative instruction, below, for running
+the test file.
+
+Run the tests from the exercise directory using the following command:
+
+    ruby reverse_string_test.rb
+
+To include color from the command line:
+
+    ruby -r minitest/pride reverse_string_test.rb
+
+
+## Source
+
+Introductory challenge to reverse an input string [https://medium.freecodecamp.org/how-to-reverse-a-string-in-javascript-in-3-different-ways-75e4763c68cb](https://medium.freecodecamp.org/how-to-reverse-a-string-in-javascript-in-3-different-ways-75e4763c68cb)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

exercises/reverse-string/reverse_string_test.rb

@@ -0,0 +1,35 @@
+require 'minitest/autorun'
+require_relative 'reverse_string'
+
+# Common test data version: 1.2.0 6c95c2e
+class ReverseStringTest < Minitest::Test
+  def test_an_empty_string
+    # skip
+    assert_equal "", ReverseString.reverse("")
+  end
+
+  def test_a_word
+    skip
+    assert_equal "tobor", ReverseString.reverse("robot")
+  end
+
+  def test_a_capitalized_word
+    skip
+    assert_equal "nemaR", ReverseString.reverse("Ramen")
+  end
+
+  def test_a_sentence_with_punctuation
+    skip
+    assert_equal "!yrgnuh m'I", ReverseString.reverse("I'm hungry!")
+  end
+
+  def test_a_palindrome
+    skip
+    assert_equal "racecar", ReverseString.reverse("racecar")
+  end
+
+  def test_an_even_sized_word
+    skip
+    assert_equal "reward", ReverseString.reverse("drawer")
+  end
+end