neovim/test/functional/normal/tabpage_spec.lua

local helpers = require('test.functional.helpers')(after_each)

local clear = helpers.clear
local command = helpers.command
local eq = helpers.eq
local feed = helpers.feed
local eval = helpers.eval

describe('tabpage', function()
  before_each(clear)

  it('advances to the next page via <C-W>gt', function()
    -- add some tabpages
    command('tabnew')
    command('tabnew')
    command('tabnew')

    eq(4, eval('tabpagenr()'))

    feed('<C-W>gt')

    eq(1, eval('tabpagenr()'))
  end)

  it('retreats to the previous page via <C-W>gT', function()
    -- add some tabpages
    command('tabnew')
    command('tabnew')
    command('tabnew')

    eq(4, eval('tabpagenr()'))

    feed('<C-W>gT')

    eq(3, eval('tabpagenr()'))
  end)
end)