feat(stdlib): add vim.base64 module (#25843)

Add base64 encode() and decode() functions to a vim.base64 module.

test/functional/lua/base64_spec.lua

@@ -0,0 +1,105 @@
+local helpers = require('test.functional.helpers')(after_each)
+local clear = helpers.clear
+local exec_lua = helpers.exec_lua
+local eq = helpers.eq
+local pcall_err = helpers.pcall_err
+local matches = helpers.matches
+
+describe('vim.base64', function()
+  before_each(clear)
+
+  local function encode(s)
+    return exec_lua([[return vim.base64.encode(...)]], s)
+  end
+
+  local function decode(s)
+    return exec_lua([[return vim.base64.decode(...)]], s)
+  end
+
+  it('works', function()
+    local values = {
+      '',
+      'Many hands make light work.',
+      [[
+        Call me Ishmael. Some years ago—never mind how long precisely—having little or no money in
+        my purse, and nothing particular to interest me on shore, I thought I would sail about a
+        little and see the watery part of the world.
+      ]],
+      [[
+        It is a truth universally acknowledged, that a single man in possession of a good fortune,
+        must be in want of a wife.
+      ]],
+      'Happy families are all alike; every unhappy family is unhappy in its own way.',
+      'ЁЂЃЄЅІЇЈЉЊЋЌЍЎЏАБВГДЕЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯабвгдежзийклмнопрстуфхцчшщъыьэюя',
+      'ÅÍÎÏ˝ÓÔÒÚÆ☃',
+      '𐐜 𐐔𐐇𐐝𐐀𐐡𐐇𐐓 𐐙𐐊𐐡𐐝𐐓/𐐝𐐇𐐗𐐊𐐤𐐔 𐐒𐐋𐐗 𐐒𐐌 𐐜 𐐡𐐀𐐖𐐇𐐤𐐓𐐝 𐐱𐑂 𐑄 𐐔𐐇𐐝𐐀𐐡𐐇𐐓 𐐏𐐆𐐅𐐤𐐆𐐚𐐊𐐡𐐝𐐆𐐓𐐆',
+      '👨‍👩‍👦 👨‍👩‍👧‍👦 👨‍👨‍👦 👩‍👩‍👧 👨‍👦 👨‍👧‍👦 👩‍👦 👩‍👧‍👦',
+      'مُنَاقَشَةُ سُبُلِ اِسْتِخْدَامِ اللُّغَةِ فِي النُّظُمِ الْقَائِمَةِ وَفِيم يَخُصَّ التَّطْبِيقَاتُ الْحاسُوبِيَّةُ،',
+      [[
+        Ṱ̺̺̕o͞ ̷i̲̬͇̪͙n̝̗͕v̟̜̘̦͟o̶̙̰̠kè͚̮̺̪̹̱̤ ̖t̝͕̳̣̻̪͞h̼͓̲̦̳̘̲e͇̣̰̦̬͎ ̢̼̻̱̘h͚͎͙̜̣̲ͅi̦̲̣̰̤v̻͍e̺̭̳̪̰-m̢iͅn̖̺̞̲̯̰d̵̼̟͙̩̼̘̳ ̞̥̱̳̭r̛̗̘e͙p͠r̼̞̻̭̗e̺̠̣͟s̘͇̳͍̝͉e͉̥̯̞̲͚̬͜ǹ̬͎͎̟̖͇̤t͍̬̤͓̼̭͘ͅi̪̱n͠g̴͉ ͏͉ͅc̬̟h͡a̫̻̯͘o̫̟̖͍̙̝͉s̗̦̲.̨̹͈̣
+        ̡͓̞ͅI̗̘̦͝n͇͇͙v̮̫ok̲̫̙͈i̖͙̭̹̠̞n̡̻̮̣̺g̲͈͙̭͙̬͎ ̰t͔̦h̞̲e̢̤ ͍̬̲͖f̴̘͕̣è͖ẹ̥̩l͖͔͚i͓͚̦͠n͖͍̗͓̳̮g͍ ̨o͚̪͡f̘̣̬ ̖̘͖̟͙̮c҉͔̫͖͓͇͖ͅh̵̤̣͚͔á̗̼͕ͅo̼̣̥s̱͈̺̖̦̻͢.̛̖̞̠̫̰
+        ̗̺͖̹̯͓Ṯ̤͍̥͇͈h̲́e͏͓̼̗̙̼̣͔ ͇̜̱̠͓͍ͅN͕͠e̗̱z̘̝̜̺͙p̤̺̹͍̯͚e̠̻̠͜r̨̤͍̺̖͔̖̖d̠̟̭̬̝͟i̦͖̩͓͔̤a̠̗̬͉̙n͚͜ ̻̞̰͚ͅh̵͉i̳̞v̢͇ḙ͎͟-҉̭̩̼͔m̤̭̫i͕͇̝̦n̗͙ḍ̟ ̯̲͕͞ǫ̟̯̰̲͙̻̝f ̪̰̰̗̖̭̘͘c̦͍̲̞͍̩̙ḥ͚a̮͎̟̙͜ơ̩̹͎s̤.̝̝ ҉Z̡̖̜͖̰̣͉̜a͖̰͙̬͡l̲̫̳͍̩g̡̟̼̱͚̞̬ͅo̗͜.̟
+        ̦H̬̤̗̤͝e͜ ̜̥̝̻͍̟́w̕h̖̯͓o̝͙̖͎̱̮ ҉̺̙̞̟͈W̷̼̭a̺̪͍į͈͕̭͙̯̜t̶̼̮s̘͙͖̕ ̠̫̠B̻͍͙͉̳ͅe̵h̵̬͇̫͙i̹͓̳̳̮͎̫̕n͟d̴̪̜̖ ̰͉̩͇͙̲͞ͅT͖̼͓̪͢h͏͓̮̻e̬̝̟ͅ ̤̹̝W͙̞̝͔͇͝ͅa͏͓͔̹̼̣l̴͔̰̤̟͔ḽ̫.͕
+        Z̮̞̠͙͔ͅḀ̗̞͈̻̗Ḷ͙͎̯̹̞͓G̻O̭̗̮
+      ]],
+    }
+
+    for _, v in ipairs(values) do
+      eq(v, decode(encode(v)))
+    end
+
+    -- Explicitly check encoded output
+    eq('VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wcyBvdmVyIHRoZSBsYXp5IGRvZwo=', encode('The quick brown fox jumps over the lazy dog\n'))
+
+    -- Test vectors from rfc4648
+    local rfc4648 = {
+      { '', '' },
+      { 'f', 'Zg==', },
+      { 'fo', 'Zm8=' },
+      { 'foo', 'Zm9v' },
+      { 'foob', 'Zm9vYg==' },
+      { 'fooba', 'Zm9vYmE=' },
+      { 'foobar', 'Zm9vYmFy' },
+    }
+
+    for _, v in ipairs(rfc4648) do
+      local input = v[1]
+      local output = v[2]
+      eq(output, encode(input))
+      eq(input, decode(output))
+    end
+  end)
+
+  it('detects invalid input', function()
+    local invalid = {
+      'A',
+      'AA',
+      'AAA',
+      'A..A',
+      'AA=A',
+      'AA/=',
+      'A/==',
+      'A===',
+      '====',
+      'Zm9vYmFyZm9vYmFyA..A',
+      'Zm9vYmFyZm9vYmFyAA=A',
+      'Zm9vYmFyZm9vYmFyAA/=',
+      'Zm9vYmFyZm9vYmFyA/==',
+      'Zm9vYmFyZm9vYmFyA===',
+      'A..AZm9vYmFyZm9vYmFy',
+      'Zm9vYmFyZm9vAA=A',
+      'Zm9vYmFyZm9vAA/=',
+      'Zm9vYmFyZm9vA/==',
+      'Zm9vYmFyZm9vA===',
+    }
+
+    for _, v in ipairs(invalid) do
+      eq('Invalid input', pcall_err(decode, v))
+    end
+
+    eq('Expected 1 argument', pcall_err(encode))
+    eq('Expected 1 argument', pcall_err(decode))
+    matches('expected string', pcall_err(encode, 42))
+    matches('expected string', pcall_err(decode, 42))
+  end)
+end)