Before:
  Save &shell
  Save &shellcmdflag

After:
  Restore
  let g:ale_shell = &shell

Execute(sh should be used when the shell is fish):
  if !has('win32')
    " Set something else, so we will replace that too.
    let &shellcmdflag = '-f'
    let &shell = 'fish'

    AssertEqual ['/bin/sh', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar')

    let &shell = '/usr/bin/fish'

    AssertEqual ['/bin/sh', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar')

    let &shell = '/usr/local/bin/fish'

    AssertEqual ['/bin/sh', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar')
  endif

Execute(sh should be used when the shell is powershell):
  if !has('win32')
    " Set something else, so we will replace that too.
    let &shellcmdflag = '-f'
    let &shell = 'pwsh'

    AssertEqual ['/bin/sh', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar')

    let &shell = '/usr/bin/pwsh'

    AssertEqual ['/bin/sh', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar')

    let &shell = '/usr/local/bin/pwsh'

    AssertEqual ['/bin/sh', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar')
  endif

Execute(Other shells should be used when set):
  if !has('win32')
    let &shell = '/bin/bash'
    let &shellcmdflag = '-c'
    let g:ale_shell = &shell

    AssertEqual ['/bin/bash', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), 'foobar')
  endif

Execute(cmd /s/c as a string should be used on Windows):
  if has('win32')
    let &shell = 'who cares'
    let &shellcmdflag = 'whatever'

    AssertEqual 'cmd /s/c "foobar"', ale#job#PrepareCommand(bufnr(''), 'foobar')
  endif

Execute(Setting ale_shell should cause ale#job#PrepareCommand to use set shell):
  if !has('win32')
    let g:ale_shell = '/foo/bar'

    AssertEqual ['/foo/bar', '-c', 'foobar'], ale#job#PrepareCommand(bufnr(''), "foobar")
  endif