path: root/test/functional/ui/screen.lua

-- This module contains the Screen class, a complete Nvim UI implementation
-- designed for functional testing (verifying screen state, in particular).
--
-- Screen:expect() takes a string representing the expected screen state and an
-- optional set of attribute identifiers for checking highlighted characters.
--
-- Example usage:
--
--     local screen = Screen.new(25, 10)
--     -- Attach the screen to the current Nvim instance.
--     screen:attach()
--     -- Enter insert-mode and type some text.
--     feed('ihello screen')
--     -- Assert the expected screen state.
--     screen:expect([[
--       hello screen             |
--       ~                        |
--       ~                        |
--       ~                        |
--       ~                        |
--       ~                        |
--       ~                        |
--       ~                        |
--       ~                        |
--       -- INSERT --             |
--     ]]) -- <- Last line is stripped
--
-- Since screen updates are received asynchronously, expect() actually specifies
-- the _eventual_ screen state.
--
-- This is how expect() works:
--  * It starts the event loop with a timeout.
--  * Each time it receives an update it checks that against the expected state.
--    * If the expected state matches the current state, the event loop will be
--      stopped and expect() will return.
--    * If the timeout expires, the last match error will be reported and the
--      test will fail.
--
-- Continuing the above example, say we want to assert that "-- INSERT --" is
-- highlighted with the bold attribute. The expect() call should look like this:
--
--     NonText = Screen.colors.Blue
--     screen:expect([[
--       hello screen             |
--       ~                        |
--       ~                        |
--       ~                        |
--       ~                        |
--       ~                        |
--       ~                        |
--       ~                        |
--       ~                        |
--       {b:-- INSERT --}             |
--     ]], {b = {bold = true}}, {{bold = true, foreground = NonText}})
--
-- In this case "b" is a string associated with the set composed of one
-- attribute: bold. Note that since the {b:} markup is not a real part of the
-- screen, the delimiter "|" moved to the right. Also, the highlighting of the
-- NonText markers "~" is ignored in this test.
--
-- Tests will often share a group of attribute sets to expect(). Those can be
-- defined at the beginning of a test:
--
--    NonText = Screen.colors.Blue
--    screen:set_default_attr_ids( {
--      [1] = {reverse = true, bold = true},
--      [2] = {reverse = true}
--    })
--    screen:set_default_attr_ignore( {{}, {bold=true, foreground=NonText}} )
--
-- To help write screen tests, see Screen:snapshot_util().
-- To debug screen tests, see Screen:redraw_debug().

local helpers = require('test.functional.helpers')(nil)
local request, run, uimeths = helpers.request, helpers.run, helpers.uimeths
local dedent = helpers.dedent

local Screen = {}
Screen.__index = Screen

local debug_screen

local default_screen_timeout = 3500
if os.getenv('VALGRIND') then
  default_screen_timeout = default_screen_timeout * 3
end

if os.getenv('CI') then
  default_screen_timeout = default_screen_timeout * 3
end

do
  local spawn, nvim_prog = helpers.spawn, helpers.nvim_prog
  local session = spawn({nvim_prog, '-u', 'NONE', '-i', 'NONE', '-N', '--embed'})
  local status, rv = session:request('nvim_get_color_map')
  if not status then
    print('failed to get color map')
    os.exit(1)
  end
  local colors = rv
  local colornames = {}
  for name, rgb in pairs(colors) do
    -- we disregard the case that colornames might not be unique, as
    -- this is just a helper to get any canonical name of a color
    colornames[rgb] = name
  end
  session:close()
  Screen.colors = colors
  Screen.colornames = colornames
end

function Screen.debug(command)
  if not command then
    command = 'pynvim -n -c '
  end
  command = command .. request('vim_eval', '$NVIM_LISTEN_ADDRESS')
  if debug_screen then
    debug_screen:close()
  end
  debug_screen = io.popen(command, 'r')
  debug_screen:read()
end

function Screen.new(width, height)
  if not width then
    width = 53
  end
  if not height then
    height = 14
  end
  local self = setmetatable({
    timeout = default_screen_timeout,
    title = '',
    icon = '',
    bell = false,
    update_menu = false,
    visual_bell = false,
    suspended = false,
    mode = 'normal',
    _default_attr_ids = nil,
    _default_attr_ignore = nil,
    _mouse_enabled = true,
    _attrs = {},
    _cursor = {
      row = 1, col = 1
    },
    _busy = false
  }, Screen)
  self:_handle_resize(width, height)
  return self
end

function Screen:set_default_attr_ids(attr_ids)
  self._default_attr_ids = attr_ids
end

function Screen:set_default_attr_ignore(attr_ignore)
  self._default_attr_ignore = attr_ignore
end

function Screen:attach(options)
  if options == nil then
    options = {rgb=true}
  end
  uimeths.attach(self._width, self._height, options)
end

function Screen:detach()
  uimeths.detach()
end

function Screen:try_resize(columns, rows)
  uimeths.try_resize(columns, rows)
  -- Give ourselves a chance to _handle_resize, which requires using
  -- self.sleep() (for the resize notification) rather than run()
  self:sleep(0.1)
end

-- Asserts that `expected` eventually matches the screen state.
--
-- expected:    Expected screen state (string). Each line represents a screen
--              row. Last character of each row (typically "|") is stripped.
--              Common indentation is stripped.
--              Used as `condition` if NOT a string; must be the ONLY arg then.
-- attr_ids:    Expected text attributes. Screen rows are transformed according
--              to this table, as follows: each substring S composed of
--              characters having the same attributes will be substituted by
--              "{K:S}", where K is a key in `attr_ids`. Any unexpected
--              attributes in the final state are an error.
-- attr_ignore: Ignored text attributes, or `true` to ignore all.
-- condition:   Function asserting some arbitrary condition.
-- any:         true: Succeed if `expected` matches ANY screen line(s).
--              false (default): `expected` must match screen exactly.
function Screen:expect(expected, attr_ids, attr_ignore, condition, any)
  local expected_rows = {}
  if type(expected) ~= "string" then
    assert(not (attr_ids or attr_ignore or condition or any))
    condition = expected
    expected = nil
  else
    -- Remove the last line and dedent.
    expected = dedent(expected:gsub('\n[ ]+$', ''))
    for row in expected:gmatch('[^\n]+') do
      row = row:sub(1, #row - 1) -- Last char must be the screen delimiter.
      table.insert(expected_rows, row)
    end
    if not any then
      assert(self._height == #expected_rows,
        "Expected screen state's row count(" .. #expected_rows
        .. ') differs from configured height(' .. self._height .. ') of Screen.')
    end
  end
  local ids = attr_ids or self._default_attr_ids
  local ignore = attr_ignore or self._default_attr_ignore
  self:wait(function()
    if condition ~= nil then
      local status, res = pcall(condition)
      if not status then
        return tostring(res)
      end
    end
    local actual_rows = {}
    for i = 1, self._height do
      actual_rows[i] = self:_row_repr(self._rows[i], ids, ignore)
    end

    if expected == nil then
      return
    elseif any then
      -- Search for `expected` anywhere in the screen lines.
      local actual_screen_str = table.concat(actual_rows, '\n')
      if nil == string.find(actual_screen_str, expected) then
        return (
          'Failed to match any screen lines.\n'
          .. 'Expected (anywhere): "' .. expected .. '"\n'
          .. 'Actual:\n  |' .. table.concat(actual_rows, '|\n  |') .. '|\n\n')
      end
    else
      -- `expected` must match the screen lines exactly.
      for i = 1, self._height do
        if expected_rows[i] ~= actual_rows[i] then
          local msg_expected_rows = {}
          for j = 1, #expected_rows do
            msg_expected_rows[j] = expected_rows[j]
          end
          msg_expected_rows[i] = '*' .. msg_expected_rows[i]
          actual_rows[i] = '*' .. actual_rows[i]
          return (
            'Row ' .. tostring(i) .. ' did not match.\n'
            ..'Expected:\n  |'..table.concat(msg_expected_rows, '|\n  |')..'|\n'
            ..'Actual:\n  |'..table.concat(actual_rows, '|\n  |')..'|\n\n'..[[
To print the expect() call that would assert the current screen state, use
screen:snaphot_util(). In case of non-deterministic failures, use
screen:redraw_debug() to show all intermediate screen states.  ]])
        end
      end
    end
  end)
end

function Screen:wait(check, timeout)
  local err, checked = false
  local success_seen = false
  local failure_after_success = false
  local function notification_cb(method, args)
    assert(method == 'redraw')
    self:_redraw(args)
    err = check()
    checked = true
    if not err then
      success_seen = true
      helpers.stop()
    elseif success_seen and #args > 0 then
      failure_after_success = true
      --print(require('inspect')(args))
    end

    return true
  end
  run(nil, notification_cb, nil, timeout or self.timeout)
  if not checked then
    err = check()
  end

  if failure_after_success then
    print([[

Warning: Screen changes were received after the expected state. This indicates
indeterminism in the test. Try adding wait() (or screen:expect(...)) between
asynchronous (feed(), nvim_input()) and synchronous API calls.
  - Use Screen:redraw_debug() to investigate the problem.
  - wait() can trigger redraws and consequently generate more indeterminism.
    In that case try removing every wait().
      ]])
    local tb = debug.traceback()
    local index = string.find(tb, '\n%s*%[C]')
    print(string.sub(tb,1,index))
  end

  if err then
    assert(false, err)
  end
end

function Screen:sleep(ms)
  pcall(function() self:wait(function() return "error" end, ms) end)
end

function Screen:_redraw(updates)
  for _, update in ipairs(updates) do
    -- print('--')
    -- print(require('inspect')(update))
    local method = update[1]
    for i = 2, #update do
      local handler_name = '_handle_'..method
      local handler = self[handler_name]
      if handler ~= nil then
        handler(self, unpack(update[i]))
      else
        assert(self._on_event,
          "Add Screen:"..handler_name.." or call Screen:set_on_event_handler")
        self._on_event(method, update[i])
      end
    end
    -- print(self:_current_screen())
  end
end

function Screen:set_on_event_handler(callback)
  self._on_event = callback
end

function Screen:_handle_resize(width, height)
  local rows = {}
  for _ = 1, height do
    local cols = {}
    for _ = 1, width do
      table.insert(cols, {text = ' ', attrs = {}})
    end
    table.insert(rows, cols)
  end
  self._cursor.row = 1
  self._cursor.col = 1
  self._rows = rows
  self._width = width
  self._height = height
  self._scroll_region = {
    top = 1, bot = height, left = 1, right = width
  }
end

function Screen:_handle_mode_info_set(cursor_style_enabled, mode_info)
  self._cursor_style_enabled = cursor_style_enabled
  self._mode_info = mode_info
end

function Screen:_handle_clear()
  self:_clear_block(self._scroll_region.top