test: remove use of require('test.helpers')

The test.functional.helpers and test.unit.helpers modules now include
all of the public functions from test.helpers, so there is no need to
separately require('test.helpers').

test/functional/api/keymap_spec.lua

@@ -1,5 +1,4 @@
 local helpers = require('test.functional.helpers')(after_each)
-local global_helpers = require('test.helpers')
 
 local bufmeths = helpers.bufmeths
 local clear = helpers.clear
@@ -12,8 +11,8 @@ local funcs = helpers.funcs
 local meths = helpers.meths
 local source = helpers.source
 
-local shallowcopy = global_helpers.shallowcopy
-local sleep = global_helpers.sleep
+local shallowcopy = helpers.shallowcopy
+local sleep = helpers.sleep
 
 describe('nvim_get_keymap', function()
   before_each(clear)

test/functional/api/vim_spec.lua

@@ -1,6 +1,5 @@
 local helpers = require('test.functional.helpers')(after_each)
 local Screen = require('test.functional.ui.screen')
-local global_helpers = require('test.helpers')
 
 local NIL = helpers.NIL
 local clear, nvim, eq, neq = helpers.clear, helpers.nvim, helpers.eq, helpers.neq
@@ -16,10 +15,10 @@ local request = helpers.request
 local source = helpers.source
 local next_msg = helpers.next_msg
 
-local expect_err = global_helpers.expect_err
-local format_string = global_helpers.format_string
-local intchar2lua = global_helpers.intchar2lua
-local mergedicts_copy = global_helpers.mergedicts_copy
+local expect_err = helpers.expect_err
+local format_string = helpers.format_string
+local intchar2lua = helpers.intchar2lua
+local mergedicts_copy = helpers.mergedicts_copy
 
 describe('API', function()
   before_each(clear)

test/functional/core/channels_spec.lua

@@ -1,7 +1,5 @@
-local global_helpers = require('test.helpers')
-local uname = global_helpers.uname
-
 local helpers = require('test.functional.helpers')(after_each)
+local uname = helpers.uname
 local clear, eq, eval, next_msg, ok, source = helpers.clear, helpers.eq,
    helpers.eval, helpers.next_msg, helpers.ok, helpers.source
 local command, funcs, meths = helpers.command, helpers.funcs, helpers.meths

test/functional/eval/let_spec.lua

@@ -59,7 +59,7 @@ describe(':let', function()
   end)
 
   it("multibyte env var to child process #8398 #9267",  function()
-    if (not helpers.iswin()) and require('test.helpers').isCI() then
+    if (not helpers.iswin()) and helpers.isCI() then
       -- Fails on non-Windows CI. Buffering/timing issue?
       pending('fails on unix CI', function() end)
     end

test/functional/helpers.lua

@@ -16,7 +16,6 @@ local eq = global_helpers.eq
 local ok = global_helpers.ok
 local sleep = global_helpers.sleep
 local table_contains = global_helpers.table_contains
-local table_flatten = global_helpers.table_flatten
 local write_file = global_helpers.write_file
 
 local start_dir = lfs.currentdir()

test/functional/options/defaults_spec.lua

@@ -1,5 +1,4 @@
 local helpers = require('test.functional.helpers')(after_each)
-local global_helpers = require('test.helpers')
 
 local Screen = require('test.functional.ui.screen')
 
@@ -16,7 +15,7 @@ local neq = helpers.neq
 local mkdir = helpers.mkdir
 local rmdir = helpers.rmdir
 local alter_slashes = helpers.alter_slashes
-local table_contains = global_helpers.table_contains
+local table_contains = helpers.table_contains
 
 describe('startup defaults', function()
   describe(':filetype', function()

test/functional/terminal/tui_spec.lua

@@ -1,8 +1,7 @@
 -- TUI acceptance tests.
 -- Uses :terminal as a way to send keys and assert screen state.
-local global_helpers = require('test.helpers')
-local uname = global_helpers.uname
 local helpers = require('test.functional.helpers')(after_each)
+local uname = helpers.uname
 local thelpers = require('test.functional.terminal.helpers')
 local Screen = require('test.functional.ui.screen')
 local eq = helpers.eq

test/functional/ui/options_spec.lua

@@ -1,10 +1,9 @@
-local global_helpers = require('test.helpers')
 local helpers = require('test.functional.helpers')(after_each)
 local Screen = require('test.functional.ui.screen')
 local clear = helpers.clear
 local command = helpers.command
 local eq = helpers.eq
-local shallowcopy = global_helpers.shallowcopy
+local shallowcopy = helpers.shallowcopy
 
 describe('ui receives option updates', function()
   local screen

test/functional/ui/screen.lua

@@ -71,11 +71,10 @@
 -- To help write screen tests, see Screen:snapshot_util().
 -- To debug screen tests, see Screen:redraw_debug().
 
-local global_helpers = require('test.helpers')
-local deepcopy = global_helpers.deepcopy
-local shallowcopy = global_helpers.shallowcopy
-local concat_tables = global_helpers.concat_tables
 local helpers = require('test.functional.helpers')(nil)
+local deepcopy = helpers.deepcopy
+local shallowcopy = helpers.shallowcopy
+local concat_tables = helpers.concat_tables
 local request, run_session = helpers.request, helpers.run_session
 local eq = helpers.eq
 local dedent = helpers.dedent

test/functional/ui/wildmode_spec.lua

@@ -1,7 +1,6 @@
-local global_helpers = require('test.helpers')
-local shallowcopy = global_helpers.shallowcopy
 local helpers = require('test.functional.helpers')(after_each)
 local Screen = require('test.functional.ui.screen')
+local shallowcopy = helpers.shallowcopy
 local clear, feed, command = helpers.clear, helpers.feed, helpers.command
 local iswin = helpers.iswin
 local funcs = helpers.funcs