Add canonical atbash-cipher tests for decoding

exercises/practice/atbash-cipher/.meta/config.json

@@ -3,7 +3,8 @@
     "ryanplusplus"
   ],
   "contributors": [
-    "aarti"
+    "aarti",
+    "BNAndras"
   ],
   "files": {
     "solution": [

exercises/practice/atbash-cipher/.meta/example.lua

@@ -1,32 +1,17 @@
-local alphabet = 'abcdefghijklmnopqrstuvwxyz'
-local decoder_ring = setmetatable({}, {
-  __index = function()
-    return ''
-  end
-})
-
-for i = 1, #alphabet do
-  decoder_ring[alphabet:sub(i, i)] = alphabet:reverse():sub(i, i)
-end
-
-for i = 0, 9 do
-  decoder_ring[tostring(i)] = tostring(i)
+local function inverse_char(char)
+  return string.char(219 - string.byte(char))
 end
 
-local function transcribe(plaintext)
-  return plaintext:lower():gsub('.', decoder_ring)
+local function encode(phrase)
+  local clean = string.gsub(string.lower(phrase), "[^a-z0-9]", "")
+  local decoded = string.gsub(clean, "[a-z]", inverse_char)
+  local spaced = string.gsub(decoded, ".....", "%0 ")
+  return string.match(spaced, "^%s*(.-)%s*$") or spaced
 end
 
-local function split_chunks(s)
-  local chunks = {}
-  s:gsub('..?.?.?.?', function(chunk)
-    table.insert(chunks, chunk)
-  end)
-  return table.concat(chunks, ' ')
+local function decode(phrase)
+  local clean = string.gsub(string.lower(phrase), "[^a-z0-9]", "")
+  return string.gsub(clean, "[a-z]", inverse_char)
 end
 
-return {
-  encode = function(plaintext)
-    return split_chunks(transcribe(plaintext))
-  end
-}
+return { encode = encode, decode = decode }

exercises/practice/atbash-cipher/.meta/spec_generator.lua

@@ -0,0 +1,13 @@
+return {
+  module_name = 'atbash_cipher',
+
+  generate_test = function(case)
+    local lines = {}
+    table.insert(lines, string.format("local phrase = '%s'", case.input.phrase))
+    table.insert(lines, string.format("local expected = '%s'", case.expected))
+    table.insert(lines, string.format("local result = atbash_cipher.%s(phrase)", case.property))
+    table.insert(lines, "assert.are.same(expected, result)")
+
+    return table.concat(lines, "\n")
+  end
+}

exercises/practice/atbash-cipher/atbash-cipher.lua

@@ -1,4 +1,7 @@
-return {
-  encode = function(plaintext)
-  end
-}
+local function encode(phrase)
+end
+
+local function decode(phrase)
+end
+
+return { encode = encode, decode = decode }

exercises/practice/atbash-cipher/atbash-cipher_spec.lua

@@ -1,36 +1,105 @@
-local encode = require('atbash-cipher').encode
+local atbash_cipher = require('atbash-cipher')
 
 describe('atbash-cipher', function()
-  it('should encode single letter plaintexts', function()
-    assert.are.equal('m', encode('n'))
-  end)
+  describe('encode', function()
+    it('encode yes', function()
+      local phrase = 'yes'
+      local expected = 'bvh'
+      local result = atbash_cipher.encode(phrase)
+      assert.are.same(expected, result)
+    end)
 
-  it('should encode single-chunk plaintexts', function()
-    assert.are.equal('svool', encode('hello'))
-  end)
+    it('encode no', function()
+      local phrase = 'no'
+      local expected = 'ml'
+      local result = atbash_cipher.encode(phrase)
+      assert.are.same(expected, result)
+    end)
 
-  it('should encode multi-chunk plaintexts', function()
-    assert.are.equal('nrmwy oldrm tob', encode('mindblowingly'))
-  end)
+    it('encode omg', function()
+      local phrase = 'OMG'
+      local expected = 'lnt'
+      local result = atbash_cipher.encode(phrase)
+      assert.are.same(expected, result)
+    end)
 
-  it('should encode all letters as lower-case', function()
-    assert.are.equal('svool', encode('HeLLo'))
-  end)
+    it('encode spaces', function()
+      local phrase = 'O M G'
+      local expected = 'lnt'
+      local result = atbash_cipher.encode(phrase)
+      assert.are.same(expected, result)
+    end)
 
-  it('should not encode whitespace', function()
-    assert.are.equal('svool', encode('h e l l o'))
-  end)
+    it('encode mindblowingly', function()
+      local phrase = 'mindblowingly'
+      local expected = 'nrmwy oldrm tob'
+      local result = atbash_cipher.encode(phrase)
+      assert.are.same(expected, result)
+    end)
 
-  it('should not encode punctuation', function()
-    assert.are.equal('svool', encode('h,e,l,l,o'))
-  end)
+    it('encode numbers', function()
+      local phrase = 'Testing,1 2 3, testing.'
+      local expected = 'gvhgr mt123 gvhgr mt'
+      local result = atbash_cipher.encode(phrase)
+      assert.are.same(expected, result)
+    end)
 
-  it('should not encode numbers', function()
-    assert.are.equal('sv11l', encode('he11o'))
+    it('encode deep thought', function()
+      local phrase = 'Truth is fiction.'
+      local expected = 'gifgs rhurx grlm'
+      local result = atbash_cipher.encode(phrase)
+      assert.are.same(expected, result)
+    end)
+
+    it('encode all the letters', function()
+      local phrase = 'The quick brown fox jumps over the lazy dog.'
+      local expected = 'gsvjf rxpyi ldmul cqfnk hlevi gsvoz abwlt'
+      local result = atbash_cipher.encode(phrase)
+      assert.are.same(expected, result)
+    end)
   end)
 
-  it('should encode all letters', function()
-    assert.are
-      .equal('gsvjf rxpyi ldmul cqfnk hlevi gsvoz abwlt', encode('The quick brown fox jumps over the lazy dog.'))
+  describe('decode', function()
+    it('decode exercism', function()
+      local phrase = 'vcvix rhn'
+      local expected = 'exercism'
+      local result = atbash_cipher.decode(phrase)
+      assert.are.same(expected, result)
+    end)
+
+    it('decode a sentence', function()
+      local phrase = 'zmlyh gzxov rhlug vmzhg vkkrm thglm v'
+      local expected = 'anobstacleisoftenasteppingstone'
+      local result = atbash_cipher.decode(phrase)
+      assert.are.same(expected, result)
+    end)
+
+    it('decode numbers', function()
+      local phrase = 'gvhgr mt123 gvhgr mt'
+      local expected = 'testing123testing'
+      local result = atbash_cipher.decode(phrase)
+      assert.are.same(expected, result)
+    end)
+
+    it('decode all the letters', function()
+      local phrase = 'gsvjf rxpyi ldmul cqfnk hlevi gsvoz abwlt'
+      local expected = 'thequickbrownfoxjumpsoverthelazydog'
+      local result = atbash_cipher.decode(phrase)
+      assert.are.same(expected, result)
+    end)
+
+    it('decode with too many spaces', function()
+      local phrase = 'vc vix    r hn'
+      local expected = 'exercism'
+      local result = atbash_cipher.decode(phrase)
+      assert.are.same(expected, result)
+    end)
+
+    it('decode with no spaces', function()
+      local phrase = 'zmlyhgzxovrhlugvmzhgvkkrmthglmv'
+      local expected = 'anobstacleisoftenasteppingstone'
+      local result = atbash_cipher.decode(phrase)
+      assert.are.same(expected, result)
+    end)
   end)
 end)