test: improve test conventions

Specifically, functions that are run in the context of the test runner
are put in module `test/testutil.lua` while the functions that are run
in the context of the test session are put in
`test/functional/testnvim.lua`.

Closes https://github.com/neovim/neovim/issues/27004.

36 files changed, 374 insertions, 313 deletions

diff --git a/test/functional/ui/bufhl_spec.lua b/test/functional/ui/bufhl_spec.lua
index 7ea7319cf8..5590db5bc4 100644
--- a/test/functional/ui/bufhl_spec.lua
+++ b/test/functional/ui/bufhl_spec.lua
@@ -1,9 +1,10 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
 
-local clear, feed, insert = t.clear, t.feed, t.insert
-local command, neq = t.command, t.neq
-local api = t.api
+local clear, feed, insert = n.clear, n.feed, n.insert
+local command, neq = n.command, t.neq
+local api = n.api
 local eq = t.eq
 local pcall_err = t.pcall_err
 local set_virtual_text = api.nvim_buf_set_virtual_text
diff --git a/test/functional/ui/cmdline_highlight_spec.lua b/test/functional/ui/cmdline_highlight_spec.lua
index ee8c713603..1c6f19245a 100644
--- a/test/functional/ui/cmdline_highlight_spec.lua
+++ b/test/functional/ui/cmdline_highlight_spec.lua
@@ -1,15 +1,16 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
 
 local eq = t.eq
-local feed = t.feed
-local clear = t.clear
-local api = t.api
-local fn = t.fn
-local source = t.source
-local exec_capture = t.exec_capture
+local feed = n.feed
+local clear = n.clear
+local api = n.api
+local fn = n.fn
+local source = n.source
+local exec_capture = n.exec_capture
 local dedent = t.dedent
-local command = t.command
+local command = n.command
 
 local screen
 
diff --git a/test/functional/ui/cmdline_spec.lua b/test/functional/ui/cmdline_spec.lua
index 645f3851b2..b3ec5f7535 100644
--- a/test/functional/ui/cmdline_spec.lua
+++ b/test/functional/ui/cmdline_spec.lua
@@ -1,15 +1,17 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear, feed = t.clear, t.feed
-local source = t.source
-local command = t.command
-local assert_alive = t.assert_alive
-local poke_eventloop = t.poke_eventloop
-local exec = t.exec
-local eval = t.eval
+
+local clear, feed = n.clear, n.feed
+local source = n.source
+local command = n.command
+local assert_alive = n.assert_alive
+local poke_eventloop = n.poke_eventloop
+local exec = n.exec
+local eval = n.eval
 local eq = t.eq
 local is_os = t.is_os
-local api = t.api
+local api = n.api
 
 local function new_screen(opt)
   local screen = Screen.new(25, 5)
diff --git a/test/functional/ui/cursor_spec.lua b/test/functional/ui/cursor_spec.lua
index 9bfc8c6fb9..8bfceb8cce 100644
--- a/test/functional/ui/cursor_spec.lua
+++ b/test/functional/ui/cursor_spec.lua
@@ -1,8 +1,10 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear, api = t.clear, t.api
+
+local clear, api = n.clear, n.api
 local eq = t.eq
-local command = t.command
+local command = n.command
 
 describe('ui/cursor', function()
   local screen
@@ -213,8 +215,8 @@ describe('ui/cursor', function()
     }
 
     -- Change the cursor style.
-    t.command('hi Cursor guibg=DarkGray')
-    t.command(
+    n.command('hi Cursor guibg=DarkGray')
+    n.command(
       'set guicursor=n-v-c:block,i-ci-ve:ver25,r-cr-o:hor20'
         .. ',a:blinkwait700-blinkoff400-blinkon250-Cursor/lCursor'
         .. ',sm:block-blinkwait175-blinkoff150-blinkon175'
@@ -260,8 +262,8 @@ describe('ui/cursor', function()
     end)
 
     -- Change hl groups only, should update the styles
-    t.command('hi Cursor guibg=Red')
-    t.command('hi lCursor guibg=Green')
+    n.command('hi Cursor guibg=Red')
+    n.command('hi lCursor guibg=Green')
 
     -- Update the expected values.
     for _, m in ipairs(expected_mode_info) do
@@ -280,7 +282,7 @@ describe('ui/cursor', function()
     end)
 
     -- update the highlight again to hide cursor
-    t.command('hi Cursor blend=100')
+    n.command('hi Cursor blend=100')
 
     for _, m in ipairs(expected_mode_info) do
       if m.hl_id then
diff --git a/test/functional/ui/decorations_spec.lua b/test/functional/ui/decorations_spec.lua
index 4e7245c166..ac879c33fc 100644
--- a/test/functional/ui/decorations_spec.lua
+++ b/test/functional/ui/decorations_spec.lua
@@ -1,17 +1,18 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
 
-local clear = t.clear
-local feed = t.feed
-local insert = t.insert
-local exec_lua = t.exec_lua
-local exec = t.exec
+local clear = n.clear
+local feed = n.feed
+local insert = n.insert
+local exec_lua = n.exec_lua
+local exec = n.exec
 local expect_events = t.expect_events
-local api = t.api
-local fn = t.fn
-local command = t.command
+local api = n.api
+local fn = n.fn
+local command = n.command
 local eq = t.eq
-local assert_alive = t.assert_alive
+local assert_alive = n.assert_alive
 local pcall_err = t.pcall_err
 
 describe('decorations providers', function()
@@ -723,7 +724,7 @@ describe('decorations providers', function()
     end
     ]]
 
-    t.assert_alive()
+    n.assert_alive()
   end)
 
   it('supports subpriorities (order of definitions in a query file #27131)', function()
@@ -2438,7 +2439,7 @@ describe('extmark decorations', function()
                                                         |
     ]]}
 
-    t.assert_alive()
+    n.assert_alive()
   end)
 
   it('priority ordering of overlay or win_col virtual text at same position', function()
@@ -5153,8 +5154,8 @@ l5
     insert(example_test3)
     feed 'gg'
 
-    t.command('sign define Oldsign text=x')
-    t.command([[exe 'sign place 42 line=2 name=Oldsign buffer=' . bufnr('')]])
+    n.command('sign define Oldsign text=x')
+    n.command([[exe 'sign place 42 line=2 name=Oldsign buffer=' . bufnr('')]])
 
     api.nvim_buf_set_extmark(0, ns, 0, -1, {sign_text='S1'})
     api.nvim_buf_set_extmark(0, ns, 1, -1, {sign_text='S2'})
@@ -5177,8 +5178,8 @@ l5
     insert(example_test3)
     feed 'gg'
 
-    t.command('sign define Oldsign text=x')
-    t.command([[exe 'sign place 42 line=2 name=Oldsign buffer=' . bufnr('')]])
+    n.command('sign define Oldsign text=x')
+    n.command([[exe 'sign place 42 line=2 name=Oldsign buffer=' . bufnr('')]])
 
     api.nvim_buf_set_extmark(0, ns, 0, -1, {sign_text='S1'})
     api.nvim_buf_set_extmark(0, ns, 1, -1, {sign_text='S2'})
diff --git a/test/functional/ui/diff_spec.lua b/test/functional/ui/diff_spec.lua
index 73fd7513c8..e79621f364 100644
--- a/test/functional/ui/diff_spec.lua
+++ b/test/functional/ui/diff_spec.lua
@@ -1,15 +1,16 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
 
-local feed = t.feed
-local clear = t.clear
-local command = t.command
-local insert = t.insert
+local feed = n.feed
+local clear = n.clear
+local command = n.command
+local insert = n.insert
 local write_file = t.write_file
 local dedent = t.dedent
-local exec = t.exec
+local exec = n.exec
 local eq = t.eq
-local api = t.api
+local api = n.api
 
 before_each(clear)
 
diff --git a/test/functional/ui/embed_spec.lua b/test/functional/ui/embed_spec.lua
index 934f00b288..e1abd43e20 100644
--- a/test/functional/ui/embed_spec.lua
+++ b/test/functional/ui/embed_spec.lua
@@ -1,20 +1,20 @@
-local uv = vim.uv
-
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
+local uv = vim.uv
 
-local api = t.api
-local feed = t.feed
+local api = n.api
+local feed = n.feed
 local eq = t.eq
 local neq = t.neq
-local clear = t.clear
+local clear = n.clear
 local ok = t.ok
-local fn = t.fn
-local nvim_prog = t.nvim_prog
+local fn = n.fn
+local nvim_prog = n.nvim_prog
 local retry = t.retry
 local write_file = t.write_file
 local assert_log = t.assert_log
-local check_close = t.check_close
+local check_close = n.check_close
 local is_os = t.is_os
 
 local testlog = 'Xtest-embed-log'
@@ -258,7 +258,7 @@ describe('--embed UI', function()
     }
 
     -- Change global cwd
-    t.command(string.format('cd %s/src/nvim', t.paths.test_source_path))
+    n.command(string.format('cd %s/src/nvim', t.paths.test_source_path))
 
     screen:expect {
       condition = function()
@@ -267,8 +267,8 @@ describe('--embed UI', function()
     }
 
     -- Split the window and change the cwd in the split
-    t.command('new')
-    t.command(string.format('lcd %s/test', t.paths.test_source_path))
+    n.command('new')
+    n.command(string.format('lcd %s/test', t.paths.test_source_path))
 
     screen:expect {
       condition = function()
@@ -277,7 +277,7 @@ describe('--embed UI', function()
     }
 
     -- Move to the original window
-    t.command('wincmd p')
+    n.command('wincmd p')
 
     screen:expect {
       condition = function()
@@ -286,7 +286,7 @@ describe('--embed UI', function()
     }
 
     -- Change global cwd again
-    t.command(string.format('cd %s', t.paths.test_source_path))
+    n.command(string.format('cd %s', t.paths.test_source_path))
 
     screen:expect {
       condition = function()
@@ -300,7 +300,7 @@ describe('--embed --listen UI', function()
   it('waits for connection on listening address', function()
     t.skip(t.is_os('win'))
     clear()
-    local child_server = assert(t.new_pipename())
+    local child_server = assert(n.new_pipename())
     fn.jobstart({
       nvim_prog,
       '--embed',
@@ -314,7 +314,7 @@ describe('--embed --listen UI', function()
       neq(nil, uv.fs_stat(child_server))
     end)
 
-    local child_session = t.connect(child_server)
+    local child_session = n.connect(child_server)
 
     local info_ok, api_info = child_session:request('nvim_get_api_info')
     ok(info_ok)
diff --git a/test/functional/ui/float_spec.lua b/test/functional/ui/float_spec.lua
index 99cb2e56f4..b7fb9dbd32 100644
--- a/test/functional/ui/float_spec.lua
+++ b/test/functional/ui/float_spec.lua
@@ -1,24 +1,26 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
 local os = require('os')
-local clear, feed = t.clear, t.feed
-local assert_alive = t.assert_alive
-local command, feed_command = t.command, t.feed_command
-local eval = t.eval
+
+local clear, feed = n.clear, n.feed
+local assert_alive = n.assert_alive
+local command, feed_command = n.command, n.feed_command
+local eval = n.eval
 local eq = t.eq
 local neq = t.neq
-local expect = t.expect
-local exec = t.exec
-local exec_lua = t.exec_lua
-local insert = t.insert
-local api = t.api
-local fn = t.fn
-local run = t.run
+local expect = n.expect
+local exec = n.exec
+local exec_lua = n.exec_lua
+local insert = n.insert
+local api = n.api
+local fn = n.fn
+local run = n.run
 local pcall_err = t.pcall_err
 local tbl_contains = vim.tbl_contains
-local curbuf = t.api.nvim_get_current_buf
-local curwin = t.api.nvim_get_current_win
-local curtab = t.api.nvim_get_current_tabpage
+local curbuf = n.api.nvim_get_current_buf
+local curwin = n.api.nvim_get_current_win
+local curtab = n.api.nvim_get_current_tabpage
 local NIL = vim.NIL
 
 describe('float window', function()
@@ -4120,7 +4122,7 @@ describe('float window', function()
 
     if multigrid then
       pending("supports second UI without multigrid", function()
-        local session2 = t.connect(eval('v:servername'))
+        local session2 = n.connect(eval('v:servername'))
         print(session2:request("nvim_eval", "2+2"))
         local screen2 = Screen.new(40,7)
         screen2:attach(nil, session2)
@@ -8018,7 +8020,7 @@ describe('float window', function()
     end)
 
     it("correctly redraws when overlaid windows are resized #13991", function()
-	  t.source([[
+	  n.source([[
         let popup_config = {"relative" : "editor",
                     \ "width" : 7,
                     \ "height" : 3,
@@ -8082,7 +8084,7 @@ describe('float window', function()
         ]])
       end
 
-      t.source([[
+      n.source([[
         let new_popup_config = {"width" : 1, "height" : 3}
         let new_border_config = {"width" : 3, "height" : 5}
 
@@ -8097,7 +8099,7 @@ describe('float window', function()
         nnoremap zz <cmd>call Resize()<cr>
       ]])
 
-      t.feed("zz")
+      n.feed("zz")
       if multigrid then
         screen:expect{grid=[[
         ## grid 1
diff --git a/test/functional/ui/fold_spec.lua b/test/functional/ui/fold_spec.lua
index 7e1cc546ae..2712e5ff48 100644
--- a/test/functional/ui/fold_spec.lua
+++ b/test/functional/ui/fold_spec.lua
@@ -1,13 +1,15 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear, feed, eq = t.clear, t.feed, t.eq
-local command = t.command
-local feed_command = t.feed_command
-local insert = t.insert
-local fn = t.fn
-local api = t.api
-local exec = t.exec
-local assert_alive = t.assert_alive
+
+local clear, feed, eq = n.clear, n.feed, t.eq
+local command = n.command
+local feed_command = n.feed_command
+local insert = n.insert
+local fn = n.fn
+local api = n.api
+local exec = n.exec
+local assert_alive = n.assert_alive
 
 local content1 = [[
         This is a
diff --git a/test/functional/ui/highlight_spec.lua b/test/functional/ui/highlight_spec.lua
index bb17b1ec6c..b7b46ddfae 100644
--- a/test/functional/ui/highlight_spec.lua
+++ b/test/functional/ui/highlight_spec.lua
@@ -1,13 +1,15 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
 local os = require('os')
-local clear, feed, insert = t.clear, t.feed, t.insert
-local command, exec = t.command, t.exec
-local eval = t.eval
-local feed_command, eq = t.feed_command, t.eq
-local fn = t.fn
-local api = t.api
-local exec_lua = t.exec_lua
+
+local clear, feed, insert = n.clear, n.feed, n.insert
+local command, exec = n.command, n.exec
+local eval = n.eval
+local feed_command, eq = n.feed_command, t.eq
+local fn = n.fn
+local api = n.api
+local exec_lua = n.exec_lua
 
 describe('colorscheme compatibility', function()
   before_each(function()
@@ -2196,7 +2198,7 @@ describe("'winhighlight' highlight", function()
     ]],
     }
 
-    t.assert_alive()
+    n.assert_alive()
   end)
 
   it('can redraw statusline on cursor movement', function()
diff --git a/test/functional/ui/hlstate_spec.lua b/test/functional/ui/hlstate_spec.lua
index 03802fc1b2..8d14c9f73d 100644
--- a/test/functional/ui/hlstate_spec.lua
+++ b/test/functional/ui/hlstate_spec.lua
@@ -1,11 +1,12 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-
-local clear, insert = t.clear, t.insert
-local command = t.command
-local api = t.api
-local testprg = t.testprg
 local tt = require('test.functional.terminal.testutil')
+
+local clear, insert = n.clear, n.insert
+local command = n.command
+local api = n.api
+local testprg = n.testprg
 local skip = t.skip
 local is_os = t.is_os
 
@@ -381,7 +382,7 @@ describe('ext_hlstate detailed highlights', function()
       },
     }
 
-    t.feed('3ggV2jd')
+    n.feed('3ggV2jd')
     --screen:redraw_debug()
     screen:expect {
       grid = [[
@@ -478,7 +479,7 @@ describe('ext_hlstate detailed highlights', function()
       },
     }
 
-    t.feed('3ggV2jd')
+    n.feed('3ggV2jd')
     --screen:redraw_debug()
     screen:expect {
       grid = [[
@@ -512,7 +513,7 @@ describe('ext_hlstate detailed highlights', function()
     end
     insert('last line')
 
-    t.feed('gg')
+    n.feed('gg')
     screen:expect {
       grid = [[
       ^first line                              |
@@ -555,7 +556,7 @@ describe('ext_hlstate detailed highlights', function()
       },
     }
 
-    t.feed(string.format('3ggV%ijd', num_lines - 2))
+    n.feed(string.format('3ggV%ijd', num_lines - 2))
     --screen:redraw_debug(nil, nil, 100000)
 
     local expected_ids = {}
diff --git a/test/functional/ui/inccommand_spec.lua b/test/functional/ui/inccommand_spec.lua
index 6463814877..6bcfae2eee 100644
--- a/test/functional/ui/inccommand_spec.lua
+++ b/test/functional/ui/inccommand_spec.lua
@@ -1,22 +1,24 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear = t.clear
-local command = t.command
+
+local clear = n.clear
+local command = n.command
 local eq = t.eq
-local eval = t.eval
-local expect = t.expect
-local feed = t.feed
-local insert = t.insert
-local fn = t.fn
-local api = t.api
+local eval = n.eval
+local expect = n.expect
+local feed = n.feed
+local insert = n.insert
+local fn = n.fn
+local api = n.api
 local neq = t.neq
 local ok = t.ok
 local retry = t.retry
-local source = t.source
-local poke_eventloop = t.poke_eventloop
+local source = n.source
+local poke_eventloop = n.poke_eventloop
 local sleep = vim.uv.sleep
-local testprg = t.testprg
-local assert_alive = t.assert_alive
+local testprg = n.testprg
+local assert_alive = n.assert_alive
 
 local default_text = [[
   Inc substitution on
diff --git a/test/functional/ui/inccommand_user_spec.lua b/test/functional/ui/inccommand_user_spec.lua
index 6a11c8e9a7..12f3640b54 100644
--- a/test/functional/ui/inccommand_user_spec.lua
+++ b/test/functional/ui/inccommand_user_spec.lua
@@ -1,13 +1,15 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local api = t.api
-local clear = t.clear
+
+local api = n.api
+local clear = n.clear
 local eq = t.eq
-local exec_lua = t.exec_lua
-local insert = t.insert
-local feed = t.feed
-local command = t.command
-local assert_alive = t.assert_alive
+local exec_lua = n.exec_lua
+local insert = n.insert
+local feed = n.feed
+local command = n.command
+local assert_alive = n.assert_alive
 
 -- Implements a :Replace command that works like :substitute and has multibuffer support.
 local setup_replace_cmd = [[
diff --git a/test/functional/ui/input_spec.lua b/test/functional/ui/input_spec.lua
index 8becaf918b..f377939458 100644
--- a/test/functional/ui/input_spec.lua
+++ b/test/functional/ui/input_spec.lua
@@ -1,16 +1,18 @@
-local t = require('test.functional.testutil')()
-local clear, feed_command = t.clear, t.feed_command
-local feed, next_msg, eq = t.feed, t.next_msg, t.eq
-local command = t.command
-local expect = t.expect
-local curbuf_contents = t.curbuf_contents
-local api = t.api
-local exec_lua = t.exec_lua
-local write_file = t.write_file
-local fn = t.fn
-local eval = t.eval
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
 
+local clear, feed_command = n.clear, n.feed_command
+local feed, next_msg, eq = n.feed, n.next_msg, t.eq
+local command = n.command
+local expect = n.expect
+local curbuf_contents = n.curbuf_contents
+local api = n.api
+local exec_lua = n.exec_lua
+local write_file = t.write_file
+local fn = n.fn
+local eval = n.eval
+
 before_each(clear)
 
 describe('mappings', function()
diff --git a/test/functional/ui/linematch_spec.lua b/test/functional/ui/linematch_spec.lua
index 475f9c524b..03eed5a49c 100644
--- a/test/functional/ui/linematch_spec.lua
+++ b/test/functional/ui/linematch_spec.lua
@@ -1,8 +1,9 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
 
-local feed = t.feed
-local clear = t.clear
+local feed = n.feed
+local clear = n.clear
 local write_file = t.write_file
 
 describe('Diff mode screen with 3 diffs open', function()
@@ -1094,10 +1095,10 @@ describe('regressions', function()
     screen = Screen.new(100, 20)
     screen:attach()
     -- line must be greater than MATCH_CHAR_MAX_LEN
-    t.api.nvim_buf_set_lines(0, 0, -1, false, { string.rep('a', 1000) .. 'hello' })
-    t.exec 'vnew'
-    t.api.nvim_buf_set_lines(0, 0, -1, false, { string.rep('a', 1010) .. 'world' })
-    t.exec 'windo diffthis'
+    n.api.nvim_buf_set_lines(0, 0, -1, false, { string.rep('a', 1000) .. 'hello' })
+    n.exec 'vnew'
+    n.api.nvim_buf_set_lines(0, 0, -1, false, { string.rep('a', 1010) .. 'world' })
+    n.exec 'windo diffthis'
   end)
 
   it('properly computes filler lines for hunks bigger than linematch limit', function()
@@ -1109,10 +1110,10 @@ describe('regressions', function()
     for i = 0, 29 do
       lines[#lines + 1] = tostring(i)
     end
-    t.api.nvim_buf_set_lines(0, 0, -1, false, lines)
-    t.exec 'vnew'
-    t.api.nvim_buf_set_lines(0, 0, -1, false, { '00', '29' })
-    t.exec 'windo diffthis'
+    n.api.nvim_buf_set_lines(0, 0, -1, false, lines)
+    n.exec 'vnew'
+    n.api.nvim_buf_set_lines(0, 0, -1, false, { '00', '29' })
+    n.exec 'windo diffthis'
     feed('<C-e>')
     screen:expect {
       grid = [[
diff --git a/test/functional/ui/messages_spec.lua b/test/functional/ui/messages_spec.lua
index 9fa700c104..ca52a265fa 100644
--- a/test/functional/ui/messages_spec.lua
+++ b/test/functional/ui/messages_spec.lua
@@ -1,25 +1,27 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear, feed = t.clear, t.feed
-local eval = t.eval
+
+local clear, feed = n.clear, n.feed
+local eval = n.eval
 local eq = t.eq
 local neq = t.neq
-local command = t.command
-local set_method_error = t.set_method_error
-local api = t.api
-local async_meths = t.async_meths
+local command = n.command
+local set_method_error = n.set_method_error
+local api = n.api
+local async_meths = n.async_meths
 local test_build_dir = t.paths.test_build_dir
-local nvim_prog = t.nvim_prog
-local testprg = t.testprg
-local exec = t.exec
-local exec_capture = t.exec_capture
-local exc_exec = t.exc_exec
-local exec_lua = t.exec_lua
-local poke_eventloop = t.poke_eventloop
-local assert_alive = t.assert_alive
+local nvim_prog = n.nvim_prog
+local testprg = n.testprg
+local exec = n.exec
+local exec_capture = n.exec_capture
+local exc_exec = n.exc_exec
+local exec_lua = n.exec_lua
+local poke_eventloop = n.poke_eventloop
+local assert_alive = n.assert_alive
 local retry = t.retry
 local is_os = t.is_os
-local fn = t.fn
+local fn = n.fn
 local skip = t.skip
 
 describe('ui/ext_messages', function()
@@ -2723,13 +2725,13 @@ end)
 it('pager works in headless mode with UI attached', function()
   skip(is_os('win'))
   clear()
-  local child_server = assert(t.new_pipename())
+  local child_server = assert(n.new_pipename())
   fn.jobstart({ nvim_prog, '--clean', '--headless', '--listen', child_server })
   retry(nil, nil, function()
     neq(nil, vim.uv.fs_stat(child_server))
   end)
 
-  local child_session = t.connect(child_server)
+  local child_session = n.connect(child_server)
   local child_screen = Screen.new(40, 6)
   child_screen:attach(nil, child_session)
   child_screen._default_attr_ids = nil -- TODO: unskip with new color scheme
diff --git a/test/functional/ui/mode_spec.lua b/test/functional/ui/mode_spec.lua
index d301660b45..f623cfda06 100644
--- a/test/functional/ui/mode_spec.lua
+++ b/test/functional/ui/mode_spec.lua
@@ -1,8 +1,9 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
 
-local clear, feed, insert = t.clear, t.feed, t.insert
-local command = t.command
+local clear, feed, insert = n.clear, n.feed, n.insert
+local command = n.command
 local retry = t.retry
 
 describe('ui mode_change event', function()
diff --git a/test/functional/ui/mouse_spec.lua b/test/functional/ui/mouse_spec.lua
index a863b90549..42c877fd92 100644
--- a/test/functional/ui/mouse_spec.lua
+++ b/test/functional/ui/mouse_spec.lua
@@ -1,11 +1,13 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear, feed, api = t.clear, t.feed, t.api
-local insert, feed_command = t.insert, t.feed_command
-local eq, fn = t.eq, t.fn
-local poke_eventloop = t.poke_eventloop
-local command = t.command
-local exec = t.exec
+
+local clear, feed, api = n.clear, n.feed, n.api
+local insert, feed_command = n.insert, n.feed_command
+local eq, fn = t.eq, n.fn
+local poke_eventloop = n.poke_eventloop
+local command = n.command
+local exec = n.exec
 
 describe('ui/mouse/input', function()
   local screen
@@ -575,7 +577,7 @@ describe('ui/mouse/input', function()
       :tabprevious             |
     ]])
     feed('<LeftMouse><10,0><LeftRelease>') -- go to second tab
-    t.poke_eventloop()
+    n.poke_eventloop()
     feed('<LeftMouse><0,1>')
     screen:expect([[
       {tab: + foo }{sel: + bar }{fill:          }{tab:X}|
@@ -1856,8 +1858,8 @@ describe('ui/mouse/input', function()
 
   it('feeding <MouseMove> in Normal mode does not use uninitialized memory #19480', function()
     feed('<MouseMove>')
-    t.poke_eventloop()
-    t.assert_alive()
+    n.poke_eventloop()
+    n.assert_alive()
   end)
 
   it('mousemodel=popup_setpos', function()
diff --git a/test/functional/ui/multibyte_spec.lua b/test/functional/ui/multibyte_spec.lua
index 5a6258ffd0..da9d13762c 100644
--- a/test/functional/ui/multibyte_spec.lua
+++ b/test/functional/ui/multibyte_spec.lua
@@ -1,12 +1,14 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear = t.clear
-local command = t.command
-local feed = t.feed
-local feed_command = t.feed_command
-local insert = t.insert
-local fn = t.fn
-local api = t.api
+
+local clear = n.clear
+local command = n.command
+local feed = n.feed
+local feed_command = n.feed_command
+local insert = n.insert
+local fn = n.fn
+local api = n.api
 local split = vim.split
 local dedent = t.dedent
 
diff --git a/test/functional/ui/multigrid_spec.lua b/test/functional/ui/multigrid_spec.lua
index 3b2e2194bd..b30d29fa55 100644
--- a/test/functional/ui/multigrid_spec.lua
+++ b/test/functional/ui/multigrid_spec.lua
@@ -1,12 +1,14 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear = t.clear
-local feed, command, insert = t.feed, t.command, t.insert
+
+local clear = n.clear
+local feed, command, insert = n.feed, n.command, n.insert
 local eq = t.eq
-local fn = t.fn
-local api = t.api
-local curwin = t.api.nvim_get_current_win
-local poke_eventloop = t.poke_eventloop
+local fn = n.fn
+local api = n.api
+local curwin = n.api.nvim_get_current_win
+local poke_eventloop = n.poke_eventloop
 
 
 describe('ext_multigrid', function()
diff --git a/test/functional/ui/options_spec.lua b/test/functional/ui/options_spec.lua
index e081cbefe3..b40ff29dec 100644
--- a/test/functional/ui/options_spec.lua
+++ b/test/functional/ui/options_spec.lua
@@ -1,10 +1,12 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear = t.clear
-local command = t.command
+
+local clear = n.clear
+local command = n.command
 local eq = t.eq
 local shallowcopy = t.shallowcopy
-local eval = t.eval
+local eval = n.eval
 
 describe('UI receives option updates', function()
   local screen
diff --git a/test/functional/ui/output_spec.lua b/test/functional/ui/output_spec.lua
index b09f1e0d03..4f6454a0fb 100644
--- a/test/functional/ui/output_spec.lua
+++ b/test/functional/ui/output_spec.lua
@@ -1,18 +1,19 @@
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local t = require('test.functional.testutil')()
 local tt = require('test.functional.terminal.testutil')
 
-local assert_alive = t.assert_alive
-local mkdir, write_file, rmdir = t.mkdir, t.write_file, t.rmdir
+local assert_alive = n.assert_alive
+local mkdir, write_file, rmdir = t.mkdir, t.write_file, n.rmdir
 local eq = t.eq
-local feed = t.feed
-local feed_command = t.feed_command
-local clear = t.clear
-local command = t.command
-local testprg = t.testprg
-local nvim_dir = t.nvim_dir
-local has_powershell = t.has_powershell
-local set_shell_powershell = t.set_shell_powershell
+local feed = n.feed
+local feed_command = n.feed_command
+local clear = n.clear
+local command = n.command
+local testprg = n.testprg
+local nvim_dir = n.nvim_dir
+local has_powershell = n.has_powershell
+local set_shell_powershell = n.set_shell_powershell
 local skip = t.skip
 local is_os = t.is_os
 
@@ -30,7 +31,7 @@ describe('shell command :!', function()
       '--cmd',
       'colorscheme vim',
       '--cmd',
-      t.nvim_set .. ' notermguicolors',
+      n.nvim_set .. ' notermguicolors',
     })
     screen:expect([[
       {1: }                                                 |
@@ -81,7 +82,7 @@ describe('shell command :!', function()
       {3:-- TERMINAL --}                                    |
     ]],
       {
-        -- test/functional/testutil.lua defaults to background=light.
+        -- test/functional/testnvim.lua defaults to background=light.
         [1] = { reverse = true },
         [3] = { bold = true },
         [10] = { foreground = 2 },
diff --git a/test/functional/ui/popupmenu_spec.lua b/test/functional/ui/popupmenu_spec.lua
index 6ec098e8cd..c3abc10424 100644
--- a/test/functional/ui/popupmenu_spec.lua
+++ b/test/functional/ui/popupmenu_spec.lua
@@ -1,17 +1,19 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local assert_alive = t.assert_alive
-local clear, feed = t.clear, t.feed
-local source = t.source
-local insert = t.insert
-local api = t.api
-local async_meths = t.async_meths
-local command = t.command
-local fn = t.fn
+
+local assert_alive = n.assert_alive
+local clear, feed = n.clear, n.feed
+local source = n.source
+local insert = n.insert
+local api = n.api
+local async_meths = n.async_meths
+local command = n.command
+local fn = n.fn
 local eq = t.eq
 local pcall_err = t.pcall_err
-local exec_lua = t.exec_lua
-local exec = t.exec
+local exec_lua = n.exec_lua
+local exec = n.exec
 
 describe('ui/ext_popupmenu', function()
   local screen
diff --git a/test/functional/ui/quickfix_spec.lua b/test/functional/ui/quickfix_spec.lua
index 1438d586e9..73923a153a 100644
--- a/test/functional/ui/quickfix_spec.lua
+++ b/test/functional/ui/quickfix_spec.lua
@@ -1,7 +1,8 @@
-local t = require('test.functional.testutil')()
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear, feed, api = t.clear, t.feed, t.api
-local insert, command = t.insert, t.command
+
+local clear, feed, api = n.clear, n.feed, n.api
+local insert, command = n.insert, n.command
 
 describe('quickfix selection highlight', function()
   local screen
diff --git a/test/functional/ui/screen.lua b/test/functional/ui/screen.lua
index a9b3fb80d3..4625ce8553 100644
--- a/test/functional/ui/screen.lua
+++ b/test/functional/ui/screen.lua
@@ -70,17 +70,19 @@
 -- To help write screen tests, see Screen:snapshot_util().
 -- To debug screen tests, see Screen:redraw_debug().
 
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local busted = require('busted')
+
 local deepcopy = vim.deepcopy
 local shallowcopy = t.shallowcopy
 local concat_tables = t.concat_tables
 local pesc = vim.pesc
-local run_session = t.run_session
+local run_session = n.run_session
 local eq = t.eq
 local dedent = t.dedent
-local get_session = t.get_session
-local create_callindex = t.create_callindex
+local get_session = n.get_session
+local create_callindex = n.create_callindex
 
 local inspect = vim.inspect
 
diff --git a/test/functional/ui/screen_basic_spec.lua b/test/functional/ui/screen_basic_spec.lua
index 1bbe845bdd..54580bf47c 100644
--- a/test/functional/ui/screen_basic_spec.lua
+++ b/test/functional/ui/screen_basic_spec.lua
@@ -1,15 +1,17 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local spawn, set_session, clear = t.spawn, t.set_session, t.clear
-local feed, command = t.feed, t.command
-local insert = t.insert
+
+local spawn, set_session, clear = n.spawn, n.set_session, n.clear
+local feed, command = n.feed, n.command
+local insert = n.insert
 local eq = t.eq
-local fn, api = t.fn, t.api
+local fn, api = n.fn, n.api
 
 describe('screen', function()
   local screen
   local nvim_argv = {
-    t.nvim_prog,
+    n.nvim_prog,
     '-u',
     'NONE',
     '-i',
@@ -700,7 +702,7 @@ describe('Screen default colors', function()
     local extra = (light and ' background=light') or ''
 
     local nvim_argv = {
-      t.nvim_prog,
+      n.nvim_prog,
       '-u',
       'NONE',
       '-i',
diff --git a/test/functional/ui/searchhl_spec.lua b/test/functional/ui/searchhl_spec.lua
index 8a5529567b..8bdf528412 100644
--- a/test/functional/ui/searchhl_spec.lua
+++ b/test/functional/ui/searchhl_spec.lua
@@ -1,12 +1,14 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear, feed, insert = t.clear, t.feed, t.insert
-local command = t.command
-local feed_command = t.feed_command
+
+local clear, feed, insert = n.clear, n.feed, n.insert
+local command = n.command
+local feed_command = n.feed_command
 local eq = t.eq
-local eval = t.eval
-local fn = t.fn
-local testprg = t.testprg
+local eval = n.eval
+local fn = n.fn
+local testprg = n.testprg
 
 describe('search highlighting', function()
   local screen
diff --git a/test/functional/ui/sign_spec.lua b/test/functional/ui/sign_spec.lua
index a2eb6124ee..c1fc5ac538 100644
--- a/test/functional/ui/sign_spec.lua
+++ b/test/functional/ui/sign_spec.lua
@@ -1,7 +1,9 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local api, clear, eq = t.api, t.clear, t.eq
-local eval, exec, feed = t.eval, t.exec, t.feed
+
+local api, clear, eq = n.api, n.clear, t.eq
+local eval, exec, feed = n.eval, n.exec, n.feed
 
 describe('Signs', function()
   local screen
diff --git a/test/functional/ui/spell_spec.lua b/test/functional/ui/spell_spec.lua
index a5952b5c05..da112148cd 100644
--- a/test/functional/ui/spell_spec.lua
+++ b/test/functional/ui/spell_spec.lua
@@ -1,12 +1,14 @@
 -- Test for scenarios involving 'spell'
 
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear = t.clear
-local exec = t.exec
-local feed = t.feed
-local insert = t.insert
-local api = t.api
+
+local clear = n.clear
+local exec = n.exec
+local feed = n.feed
+local insert = n.insert
+local api = n.api
 local is_os = t.is_os
 
 describe("'spell'", function()
diff --git a/test/functional/ui/statuscolumn_spec.lua b/test/functional/ui/statuscolumn_spec.lua
index cf5126ad5c..cce9cca2ca 100644
--- a/test/functional/ui/statuscolumn_spec.lua
+++ b/test/functional/ui/statuscolumn_spec.lua
@@ -1,15 +1,17 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear = t.clear
-local command = t.command
+
+local clear = n.clear
+local command = n.command
 local eq = t.eq
-local exec = t.exec
-local eval = t.eval
-local exec_lua = t.exec_lua
-local feed = t.feed
-local api = t.api
+local exec = n.exec
+local eval = n.eval
+local exec_lua = n.exec_lua
+local feed = n.feed
+local api = n.api
 local pcall_err = t.pcall_err
-local assert_alive = t.assert_alive
+local assert_alive = n.assert_alive
 
 local mousemodels = { 'extend', 'popup', 'popup_setpos' }
 
diff --git a/test/functional/ui/statusline_spec.lua b/test/functional/ui/statusline_spec.lua
index 3c65cd46a9..3087a0cde1 100644
--- a/test/functional/ui/statusline_spec.lua
+++ b/test/functional/ui/statusline_spec.lua
@@ -1,15 +1,17 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local assert_alive = t.assert_alive
-local clear = t.clear
-local command = t.command
-local feed = t.feed
+
+local assert_alive = n.assert_alive
+local clear = n.clear
+local command = n.command
+local feed = n.feed
 local eq = t.eq
-local fn = t.fn
-local api = t.api
-local exec = t.exec
-local exec_lua = t.exec_lua
-local eval = t.eval
+local fn = n.fn
+local api = n.api
+local exec = n.exec
+local exec_lua = n.exec_lua
+local eval = n.eval
 local sleep = vim.uv.sleep
 local pcall_err = t.pcall_err
 
diff --git a/test/functional/ui/syntax_conceal_spec.lua b/test/functional/ui/syntax_conceal_spec.lua
index fea03ca6a3..be35e9bf4f 100644
--- a/test/functional/ui/syntax_conceal_spec.lua
+++ b/test/functional/ui/syntax_conceal_spec.lua
@@ -1,10 +1,12 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear, feed, command = t.clear, t.feed, t.command
+
+local clear, feed, command = n.clear, n.feed, n.command
 local eq = t.eq
-local insert = t.insert
-local poke_eventloop = t.poke_eventloop
-local exec = t.exec
+local insert = n.insert
+local poke_eventloop = n.poke_eventloop
+local exec = n.exec
 
 describe('Screen', function()
   local screen
diff --git a/test/functional/ui/tabline_spec.lua b/test/functional/ui/tabline_spec.lua
index db6b0d7f91..5cda70df21 100644
--- a/test/functional/ui/tabline_spec.lua
+++ b/test/functional/ui/tabline_spec.lua
@@ -1,9 +1,11 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear, command, eq = t.clear, t.command, t.eq
-local insert = t.insert
-local api = t.api
-local assert_alive = t.assert_alive
+
+local clear, command, eq = n.clear, n.command, t.eq
+local insert = n.insert
+local api = n.api
+local assert_alive = n.assert_alive
 
 describe('ui/ext_tabline', function()
   local screen
diff --git a/test/functional/ui/title_spec.lua b/test/functional/ui/title_spec.lua
index 09c6372573..e86fdbe5a3 100644
--- a/test/functional/ui/title_spec.lua
+++ b/test/functional/ui/title_spec.lua
@@ -1,13 +1,15 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear = t.clear
-local command = t.command
-local curwin = t.api.nvim_get_current_win
+
+local clear = n.clear
+local command = n.command
+local curwin = n.api.nvim_get_current_win
 local eq = t.eq
-local exec_lua = t.exec_lua
-local feed = t.feed
-local fn = t.fn
-local api = t.api
+local exec_lua = n.exec_lua
+local feed = n.feed
+local fn = n.fn
+local api = n.api
 local is_os = t.is_os
 
 describe('title', function()
diff --git a/test/functional/ui/wildmode_spec.lua b/test/functional/ui/wildmode_spec.lua
index 477db0fb9b..0feec6bd03 100644
--- a/test/functional/ui/wildmode_spec.lua
+++ b/test/functional/ui/wildmode_spec.lua
@@ -1,12 +1,14 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear, feed, command = t.clear, t.feed, t.command
-local fn = t.fn
-local api = t.api
+
+local clear, feed, command = n.clear, n.feed, n.command
+local fn = n.fn
+local api = n.api
 local eq = t.eq
-local eval = t.eval
+local eval = n.eval
 local retry = t.retry
-local testprg = t.testprg
+local testprg = n.testprg
 local is_os = t.is_os
 
 describe("'wildmenu'", function()
diff --git a/test/functional/ui/winbar_spec.lua b/test/functional/ui/winbar_spec.lua
index f41abff88c..fb907026a5 100644
--- a/test/functional/ui/winbar_spec.lua
+++ b/test/functional/ui/winbar_spec.lua
@@ -1,13 +1,15 @@
-local t = require('test.functional.testutil')()
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear = t.clear
-local command = t.command
-local insert = t.insert
-local api = t.api
+
+local clear = n.clear
+local command = n.command
+local insert = n.insert
+local api = n.api
 local eq = t.eq
-local poke_eventloop = t.poke_eventloop
-local feed = t.feed
-local fn = t.fn
+local poke_eventloop = n.poke_eventloop
+local feed = n.feed
+local fn = n.fn
 local pcall_err = t.pcall_err
 
 describe('winbar', function()