Execute(Relative paths should be resolved correctly):
  AssertEqual
  \ has('win32') ? '\foo\bar\baz\whatever.txt' : '/foo/bar/baz/whatever.txt',
  \ ale#path#GetAbsPath('/foo/bar/xyz', '../baz/whatever.txt')
  AssertEqual
  \ has('win32') ? '\foo\bar\xyz\whatever.txt' : '/foo/bar/xyz/whatever.txt',
  \ ale#path#GetAbsPath('/foo/bar/xyz', './whatever.txt')
  AssertEqual
  \ has('win32') ? '\foo\bar\xyz\whatever.txt' : '/foo/bar/xyz/whatever.txt',
  \ ale#path#GetAbsPath('/foo/bar/xyz', 'whatever.txt')

  if has('win32')
    AssertEqual
    \ 'C:\foo\bar\baz\whatever.txt',
    \ ale#path#GetAbsPath('C:\foo\bar\baz\xyz', '../whatever.txt')
  endif

Execute(Absolute paths should be resolved correctly):
  AssertEqual
  \ has('win32') ? '\ding\dong' : '/ding/dong',
  \ ale#path#GetAbsPath('/foo/bar/xyz', '/ding/dong')

  AssertEqual
  \ has('win32') ? '\ding\dong' : '/ding/dong',
  \ ale#path#GetAbsPath('/foo/bar/xyz', '//ding/dong')

  if has('win32')
    AssertEqual '\ding', ale#path#GetAbsPath('/foo/bar/xyz', '\\ding')
  endif