Test file to check how encoding is handled between nvim and the test suite.

test_suite_and_file_encoding_spec.lua

local helpers = require('test.functional.helpers')
local clear, feed, execute, expect, eq, eval, wait, insert = helpers.clear, helpers.feed, helpers.execute, helpers.expect, helpers.eq, helpers.eval, helpers.wait, helpers.insert

local function diff(text)
  execute('w! Xtest')
  wait()
  local file = io.open('Xtest')
  local data = file:read('*all')
  file:close()
  return eq(text, data)
end

local function mime(mime_type)
  execute('w! Xtest')
  wait()
  eq(mime_type, io.popen('file --mime-encoding Xtest'):read():sub(8))
end

describe('the lua test suite', function()

  -- This lua source file should be encoded in utf-8.  Some of the strings
  -- below use hex escape sequences to be able to store a different encoding.
  local ascii = 'ascii characters: AOU aou'
  -- The escaped characters are the German umlauts of the above "AOU aou".
  local utf8 = 'utf-8 characters: \xc3\x84\xc3\x96\xc3\x9c \xc3\xa4\xc3\xb6\xc3\xbc'
  local latin1 = 'latin1 characters: \xc4\xd6\xdc \xe4\xf6\xfc'

  before_each(clear)
  teardown(function()
    --os.remove('Xtest')
  end)
  
  it('can feed() ascii text to nvim and expect() it', function()
    -- The default fileencoding is utf-8.
    eq('', eval('&fileencoding'))
    feed('i'..ascii..'<ESC>')
    mime('ascii')
    diff(ascii..'\n')
    expect(ascii)
  end)

  it('can insert() ascii text to nvim and expect() it', function()
    -- The default fileencoding is utf-8.
    eq('', eval('&fileencoding'))
    insert(ascii)
    mime('ascii')
    diff(ascii..'\n')
    expect(ascii)
  end)

  it('can feed() utf-8 text to nvim and expect() it', function()
    -- The default fileencoding is utf-8.
    eq('', eval('&fileencoding'))
    feed('i'..utf8..'<ESC>')
    mime('utf-8')
    diff(utf8..'\n')
    expect(utf8)
  end)

  it('can insert() utf-8 text to nvim and expect() it', function()
    -- The default fileencoding is utf-8.
    eq('', eval('&fileencoding'))
    insert(utf8)
    mime('utf-8')
    diff(utf8..'\n')
    expect(utf8)
  end)

  it('can feed() latin-1 text to nvim and expect() it', function()
    execute('set fileencoding=latin1')
    feed('i'..latin1..'<ESC>')
    mime('iso-8859-1')
    diff(latin1..'\n')
    expect(latin1)
  end)

  it('can insert() latin-1 text to nvim and expect() it', function()
    execute('set fileencoding=latin1')
    insert(latin1)
    mime('iso-8859-1')
    diff(latin1..'\n')
    expect(latin1)
  end)

  it('getline() returns utf-8 text', function()
    -- The default fileencoding is utf-8.
    eq('', eval('&fileencoding'))
    insert(utf8)
    eq(utf8, eval('getline(".")'))
  end)

  it('getline() returns latin1 text', function()
    execute('set fileencoding=latin1')
    insert(latin1)
    eq(latin1, eval('getline(".")'))
  end)
end)