Merge pull request #27024 from lewis6991/test_followup

test: big cleanup followup + typing

23 files changed, 545 insertions, 440 deletions

diff --git a/runtime/lua/vim/_editor.lua b/runtime/lua/vim/_editor.lua
index 4fe601dfd5..52a21587f4 100644
--- a/runtime/lua/vim/_editor.lua
+++ b/runtime/lua/vim/_editor.lua
@@ -190,12 +190,18 @@ function vim._os_proc_children(ppid)
   return children
 end
 
+--- @class vim.inspect.Opts
+--- @field depth? integer
+--- @field newline? string
+--- @field process? fun(item:any, path: string[]): any
+
 --- Gets a human-readable representation of the given object.
 ---
 ---@see |vim.print()|
 ---@see https://github.com/kikito/inspect.lua
 ---@see https://github.com/mpeterv/vinspect
 ---@return string
+---@overload fun(x: any, opts?: vim.inspect.Opts): string
 vim.inspect = vim.inspect
 
 do
diff --git a/test/client/msgpack_rpc_stream.lua b/test/client/msgpack_rpc_stream.lua
index 4b4f30e0ec..7131940a58 100644
--- a/test/client/msgpack_rpc_stream.lua
+++ b/test/client/msgpack_rpc_stream.lua
@@ -22,6 +22,9 @@ function Response:send(value, is_error)
   self._msgpack_rpc_stream._stream:write(data)
 end
 
+--- @class test.MsgpackRpcStream
+--- @field private _stream test.Stream
+--- @field private __pack table
 local MsgpackRpcStream = {}
 MsgpackRpcStream.__index = MsgpackRpcStream
 
diff --git a/test/client/session.lua b/test/client/session.lua
index 86b4ee7103..cf3d8c4f25 100644
--- a/test/client/session.lua
+++ b/test/client/session.lua
@@ -1,6 +1,12 @@
 local uv = vim.uv
 local MsgpackRpcStream = require('test.client.msgpack_rpc_stream')
 
+--- @class test.Session
+--- @field private _pending_messages string[]
+--- @field private _msgpack_rpc_stream test.MsgpackRpcStream
+--- @field private _prepare uv.uv_prepare_t
+--- @field private _timer uv.uv_timer_t
+--- @field private _is_running boolean
 local Session = {}
 Session.__index = Session
 if package.loaded['jit'] then
@@ -26,7 +32,7 @@ end
 
 local function coroutine_exec(func, ...)
   local args = { ... }
-  local on_complete
+  local on_complete --- @type function?
 
   if #args > 0 and type(args[#args]) == 'function' then
     -- completion callback
@@ -54,6 +60,8 @@ function Session.new(stream)
   }, Session)
 end
 
+--- @param timeout integer?
+--- @return string?
 function Session:next_message(timeout)
   local function on_request(method, args, response)
     table.insert(self._pending_messages, { 'request', method, args, response })
@@ -86,6 +94,10 @@ function Session:notify(method, ...)
   self._msgpack_rpc_stream:write(method, { ... })
 end
 
+--- @param method string
+--- @param ... any
+--- @return boolean
+--- @return table
 function Session:request(method, ...)
   local args = { ... }
   local err, result
diff --git a/test/client/uv_stream.lua b/test/client/uv_stream.lua
index 9e9a69e0a1..0540c44eb2 100644
--- a/test/client/uv_stream.lua
+++ b/test/client/uv_stream.lua
@@ -1,18 +1,28 @@
 local uv = vim.uv
 
+--- @class test.Stream
+--- @field write fun(self, data: string|string[])
+--- @field read_start fun(self, cb: fun(chunk: string))
+--- @field read_stop fun(self)
+--- @field close fun(self, signal?: string)
+
+--- @class vim.StdioStream : test.Stream
+--- @field private _in uv.uv_pipe_t
+--- @field private _out uv.uv_pipe_t
 local StdioStream = {}
 StdioStream.__index = StdioStream
 
 function StdioStream.open()
   local self = setmetatable({
-    _in = uv.new_pipe(false),
-    _out = uv.new_pipe(false),
+    _in = assert(uv.new_pipe(false)),
+    _out = assert(uv.new_pipe(false)),
   }, StdioStream)
   self._in:open(0)
   self._out:open(1)
   return self
 end
 
+--- @param data string|string[]
 function StdioStream:write(data)
   self._out:write(data)
 end
@@ -35,11 +45,14 @@ function StdioStream:close()
   self._out:close()
 end
 
+--- @class test.SocketStream : test.Stream
+--- @field package _stream_error? string
+--- @field package _socket uv.uv_pipe_t
 local SocketStream = {}
 SocketStream.__index = SocketStream
 
 function SocketStream.open(file)
-  local socket = uv.new_pipe(false)
+  local socket = assert(uv.new_pipe(false))
   local self = setmetatable({
     _socket = socket,
     _stream_error = nil,
@@ -51,7 +64,7 @@ function SocketStream.open(file)
 end
 
 function SocketStream.connect(host, port)
-  local socket = uv.new_tcp()
+  local socket = assert(uv.new_tcp())
   local self = setmetatable({
     _socket = socket,
     _stream_error = nil,
@@ -96,9 +109,20 @@ function SocketStream:close()
   uv.close(self._socket)
 end
 
+--- @class test.ChildProcessStream : test.Stream
+--- @field private _proc uv.uv_process_t
+--- @field private _pid integer
+--- @field private _child_stdin uv.uv_pipe_t
+--- @field private _child_stdout uv.uv_pipe_t
+--- @field status integer
+--- @field signal integer
 local ChildProcessStream = {}
 ChildProcessStream.__index = ChildProcessStream
 
+--- @param argv string[]
+--- @param env string[]?
+--- @param io_extra uv.uv_pipe_t?
+--- @return test.ChildProcessStream
 function ChildProcessStream.spawn(argv, env, io_extra)
   local self = setmetatable({
     _child_stdin = uv.new_pipe(false),
@@ -106,13 +130,15 @@ function ChildProcessStream.spawn(argv, env, io_extra)
     _exiting = false,
   }, ChildProcessStream)
   local prog = argv[1]
-  local args = {}
+  local args = {} --- @type string[]
   for i = 2, #argv do
     args[#args + 1] = argv[i]
   end
+  --- @diagnostic disable-next-line:missing-fields
   self._proc, self._pid = uv.spawn(prog, {
     stdio = { self._child_stdin, self._child_stdout, 2, io_extra },
     args = args,
+    --- @diagnostic disable-next-line:assign-type-mismatch
     env = env,
   }, function(status, signal)
     self.status = status
diff --git a/test/deprecated.lua b/test/deprecated.lua
deleted file mode 100644
index e30dfcf3ab..0000000000
--- a/test/deprecated.lua
+++ /dev/null
@@ -1,9 +0,0 @@
--- Island of Misfit Toys
-
-local M = {}
-
-function M.redir_exec()
-  error('redir_exec is deprecated, use nvim_exec2() or pcall_err()')
-end
-
-return M
diff --git a/test/format_string.lua b/test/format_string.lua
new file mode 100644
index 0000000000..777fb652e8
--- /dev/null
+++ b/test/format_string.lua
@@ -0,0 +1,168 @@
+local luaassert = require('luassert')
+
+local M = {}
+
+local SUBTBL = {
+  '\\000',
+  '\\001',
+  '\\002',
+  '\\003',
+  '\\004',
+  '\\005',
+  '\\006',
+  '\\007',
+  '\\008',
+  '\\t',
+  '\\n',
+  '\\011',
+  '\\012',
+  '\\r',
+  '\\014',
+  '\\015',
+  '\\016',
+  '\\017',
+  '\\018',
+  '\\019',
+  '\\020',
+  '\\021',
+  '\\022',
+  '\\023',
+  '\\024',
+  '\\025',
+  '\\026',
+  '\\027',
+  '\\028',
+  '\\029',
+  '\\030',
+  '\\031',
+}
+
+--- @param v any
+--- @return string
+local function format_float(v)
+  -- On windows exponent appears to have three digits and not two
+  local ret = ('%.6e'):format(v)
+  local l, f, es, e = ret:match('^(%-?%d)%.(%d+)e([+%-])0*(%d%d+)$')
+  return l .. '.' .. f .. 'e' .. es .. e
+end
+
+-- Formats Lua value `v`.
+--
+-- TODO(justinmk): redundant with vim.inspect() ?
+--
+-- "Nice table formatting similar to screen:snapshot_util()".
+-- Commit: 520c0b91a528
+function M.format_luav(v, indent, opts)
+  opts = opts or {}
+  local linesep = '\n'
+  local next_indent_arg = nil
+  local indent_shift = opts.indent_shift or '  '
+  local next_indent
+  local nl = '\n'
+  if indent == nil then
+    indent = ''
+    linesep = ''
+    next_indent = ''
+    nl = ' '
+  else
+    next_indent_arg = indent .. indent_shift
+    next_indent = indent .. indent_shift
+  end
+  local ret = ''
+  if type(v) == 'string' then
+    if opts.literal_strings then
+      ret = v
+    else
+      local quote = opts.dquote_strings and '"' or "'"
+      ret = quote
+        .. tostring(v)
+          :gsub(opts.dquote_strings and '["\\]' or "['\\]", '\\%0')
+          :gsub('[%z\1-\31]', function(match)
+            return SUBTBL[match:byte() + 1]
+          end)
+        .. quote
+    end
+  elseif type(v) == 'table' then
+    if v == vim.NIL then
+      ret = 'REMOVE_THIS'
+    else
+      local processed_keys = {}
+      ret = '{' .. linesep
+      local non_empty = false
+      local format_luav = M.format_luav
+      for i, subv in ipairs(v) do
+        ret = ('%s%s%s,%s'):format(ret, next_indent, format_luav(subv, next_indent_arg, opts), nl)
+        processed_keys[i] = true
+        non_empty = true
+      end
+      for k, subv in pairs(v) do
+        if not processed_keys[k] then
+          if type(k) == 'string' and k:match('^[a-zA-Z_][a-zA-Z0-9_]*$') then
+            ret = ret .. next_indent .. k .. ' = '
+          else
+            ret = ('%s%s[%s] = '):format(ret, next_indent, format_luav(k, nil, opts))
+          end
+          ret = ret .. format_luav(subv, next_indent_arg, opts) .. ',' .. nl
+          non_empty = true
+        end
+      end
+      if nl == ' ' and non_empty then
+        ret = ret:sub(1, -3)
+      end
+      ret = ret .. indent .. '}'
+    end
+  elseif type(v) == 'number' then
+    if v % 1 == 0 then
+      ret = ('%d'):format(v)
+    else
+      ret = format_float(v)
+    end
+  elseif type(v) == 'nil' then
+    ret = 'nil'
+  elseif type(v) == 'boolean' then
+    ret = (v and 'true' or 'false')
+  else
+    print(type(v))
+    -- Not implemented yet
+    luaassert(false)
+  end
+  return ret
+end
+
+-- Like Python repr(), "{!r}".format(s)
+--
+-- Commit: 520c0b91a528
+function M.format_string(fmt, ...)
+  local i = 0
+  local args = { ... }
+  local function getarg()
+    i = i + 1
+    return args[i]
+  end
+  local ret = fmt:gsub('%%[0-9*]*%.?[0-9*]*[cdEefgGiouXxqsr%%]', function(match)
+    local subfmt = match:gsub('%*', function()
+      return tostring(getarg())
+    end)
+    local arg = nil
+    if subfmt:sub(-1) ~= '%' then
+      arg = getarg()
+    end
+    if subfmt:sub(-1) == 'r' or subfmt:sub(-1) == 'q' then
+      -- %r is like built-in %q, but it is supposed to single-quote strings and
+      -- not double-quote them, and also work not only for strings.
+      -- Builtin %q is replaced here as it gives invalid and inconsistent with
+      -- luajit results for e.g. "\e" on lua: luajit transforms that into `\27`,
+      -- lua leaves as-is.
+      arg = M.format_luav(arg, nil, { dquote_strings = (subfmt:sub(-1) == 'q') })
+      subfmt = subfmt:sub(1, -2) .. 's'
+    end
+    if subfmt == '%e' then
+      return format_float(arg)
+    else
+      return subfmt:format(arg)
+    end
+  end)
+  return ret
+end
+
+return M
diff --git a/test/functional/api/vim_spec.lua b/test/functional/api/vim_spec.lua
index 8d9789a3ce..91f61b5053 100644
--- a/test/functional/api/vim_spec.lua
+++ b/test/functional/api/vim_spec.lua
@@ -8,7 +8,7 @@ local assert_alive = helpers.assert_alive
 local NIL = vim.NIL
 local clear, eq, neq = helpers.clear, helpers.eq, helpers.neq
 local command = helpers.command
-local command_output = helpers.api.command_output
+local command_output = helpers.api.nvim_command_output
 local exec = helpers.exec
 local exec_capture = helpers.exec_capture
 local eval = helpers.eval
@@ -19,6 +19,7 @@ local matches = helpers.matches
 local pesc = vim.pesc
 local mkdir_p = helpers.mkdir_p
 local ok, nvim_async, feed = helpers.ok, helpers.nvim_async, helpers.feed
+local async_meths = helpers.async_meths
 local is_os = helpers.is_os
 local parse_context = helpers.parse_context
 local request = helpers.request
@@ -33,7 +34,7 @@ local insert = helpers.insert
 local skip = helpers.skip
 
 local pcall_err = helpers.pcall_err
-local format_string = helpers.format_string
+local format_string = require('test.format_string').format_string
 local intchar2lua = helpers.intchar2lua
 local mergedicts_copy = helpers.mergedicts_copy
 local endswith = vim.endswith
@@ -76,7 +77,7 @@ describe('API', function()
     eq({
       'notification',
       'nvim_error_event',
-      { error_types.Exception.id, 'Invalid method: nvim_bogus' },
+      { error_types.Exception.id, 'Invalid method: bogus' },
     }, next_msg())
     -- error didn't close channel.
     assert_alive()
@@ -84,7 +85,7 @@ describe('API', function()
 
   it('failed async request emits nvim_error_event', function()
     local error_types = api.nvim_get_api_info()[2].error_types
-    nvim_async('command', 'bogus')
+    async_meths.nvim_command('bogus')
     eq({
       'notification',
       'nvim_error_event',
@@ -2081,13 +2082,13 @@ describe('API', function()
           { ['rc'] = { 'hjkl' }, ['n'] = 97 },
         },
 
-        ['jumps'] = eval(([[
+        ['jumps'] = eval((([[
         filter(map(add(
         getjumplist()[0], { 'bufnr': bufnr('%'), 'lnum': getcurpos()[1] }),
         'filter(
         { "f": expand("#".v:val.bufnr.":p"), "l": v:val.lnum },
         { k, v -> k != "l" || v != 1 })'), '!empty(v:val.f)')
-        ]]):gsub('\n', '')),
+        ]]):gsub('\n', ''))),
 
         ['bufs'] = eval([[
         filter(map(getbufinfo(), '{ "f": v:val.name }'), '!empty(v:val.f)')
@@ -2301,7 +2302,7 @@ describe('API', function()
     end)
 
     it('can show one line', function()
-      nvim_async('err_write', 'has bork\n')
+      async_meths.nvim_err_write('has bork\n')
       screen:expect([[
         ^                                        |
         {0:~                                       }|*6
@@ -2310,7 +2311,7 @@ describe('API', function()
     end)
 
     it('shows return prompt when more than &cmdheight lines', function()
-      nvim_async('err_write', 'something happened\nvery bad\n')
+      async_meths.nvim_err_write('something happened\nvery bad\n')
       screen:expect([[
                                                 |
         {0:~                                       }|*3
@@ -2322,7 +2323,7 @@ describe('API', function()
     end)
 
     it('shows return prompt after all lines are shown', function()
-      nvim_async('err_write', 'FAILURE\nERROR\nEXCEPTION\nTRACEBACK\n')
+      async_meths.nvim_err_write('FAILURE\nERROR\nEXCEPTION\nTRACEBACK\n')
       screen:expect([[
                                                 |
         {0:~                                       }|
@@ -2337,8 +2338,8 @@ describe('API', function()
 
     it('handles multiple calls', function()
       -- without linebreak text is joined to one line
-      nvim_async('err_write', 'very ')
-      nvim_async('err_write', 'fail\n')
+      async_meths.nvim_err_write('very ')
+      async_meths.nvim_err_write('fail\n')
       screen:expect([[
         ^                                        |
         {0:~                                       }|*6
@@ -2347,7 +2348,7 @@ describe('API', function()
       helpers.poke_eventloop()
 
       -- shows up to &cmdheight lines
-      nvim_async('err_write', 'more fail\ntoo fail\n')
+      async_meths.nvim_err_write('more fail\ntoo fail\n')
       screen:expect([[
                                                 |
         {0:~                                       }|*3
@@ -2360,7 +2361,7 @@ describe('API', function()
     end)
 
     it('NUL bytes in message', function()
-      nvim_async('err_write', 'aaa\0bbb\0\0ccc\nddd\0\0\0eee\n')
+      async_meths.nvim_err_write('aaa\0bbb\0\0ccc\nddd\0\0\0eee\n')
       screen:expect {
         grid = [[
                                                 |
@@ -2389,7 +2390,7 @@ describe('API', function()
     end)
 
     it('shows only one return prompt after all lines are shown', function()
-      nvim_async('err_writeln', 'FAILURE\nERROR\nEXCEPTION\nTRACEBACK')
+      async_meths.nvim_err_writeln('FAILURE\nERROR\nEXCEPTION\nTRACEBACK')
       screen:expect([[
                                                 |
         {0:~                                       }|
@@ -3394,8 +3395,7 @@ describe('API', function()
     end)
 
     it('can show highlighted line', function()
-      nvim_async(
-        'echo',
+      async_meths.nvim_echo(
         { { 'msg_a' }, { 'msg_b', 'Statement' }, { 'msg_c', 'Special' } },
         true,
         {}
@@ -3410,7 +3410,7 @@ describe('API', function()
     end)
 
     it('can show highlighted multiline', function()
-      nvim_async('echo', { { 'msg_a\nmsg_a', 'Statement' }, { 'msg_b', 'Special' } }, true, {})
+      async_meths.nvim_echo({ { 'msg_a\nmsg_a', 'Statement' }, { 'msg_b', 'Special' } }, true, {})
       screen:expect {
         grid = [[
                                                 |
@@ -3431,7 +3431,7 @@ describe('API', function()
 
     it('can disable saving message history', function()
       command('set cmdheight=2') -- suppress Press ENTER
-      nvim_async('echo', { { 'msg\nmsg' }, { 'msg' } }, false, {})
+      async_meths.nvim_echo({ { 'msg\nmsg' }, { 'msg' } }, false, {})
       eq('', exec_capture('messages'))
     end)
   end)
diff --git a/test/functional/ex_cmds/swapfile_preserve_recover_spec.lua b/test/functional/ex_cmds/swapfile_preserve_recover_spec.lua
index 4c2e54cc6b..a6fdb919c5 100644
--- a/test/functional/ex_cmds/swapfile_preserve_recover_spec.lua
+++ b/test/functional/ex_cmds/swapfile_preserve_recover_spec.lua
@@ -222,7 +222,7 @@ describe('swapfile detection', function()
     screen2:expect(expected_no_dialog)
 
     -- With API call and shortmess+=F
-    async_meths.command('edit %')
+    async_meths.nvim_command('edit %')
     screen2:expect {
       any = [[Found a swap file by the name ".*]]
         .. [[Xtest_swapdialog_dir[/\].*]]
diff --git a/test/functional/helpers.lua b/test/functional/helpers.lua
index e9f8f30aa0..eddf336b6f 100644
--- a/test/functional/helpers.lua
+++ b/test/functional/helpers.lua
@@ -18,7 +18,7 @@ local fail = global_helpers.fail
 local module = {}
 
 local runtime_set = 'set runtimepath^=./build/lib/nvim/'
-module.nvim_prog = (os.getenv('NVIM_PRG') or global_helpers.test_build_dir .. '/bin/nvim')
+module.nvim_prog = (os.getenv('NVIM_PRG') or global_helpers.paths.test_build_dir .. '/bin/nvim')
 -- Default settings for the test session.
 module.nvim_set = (
   'set shortmess+=IS background=light termguicolors noswapfile noautoindent startofline'
@@ -55,7 +55,7 @@ if module.nvim_dir == module.nvim_prog then
   module.nvim_dir = '.'
 end
 
-local prepend_argv
+local prepend_argv --- @type string[]?
 
 if os.getenv('VALGRIND') then
   local log_file = os.getenv('VALGRIND_LOG') or 'valgrind-%p.log'
@@ -79,7 +79,7 @@ elseif os.getenv('GDB') then
 end
 
 if prepend_argv then
-  local new_nvim_argv = {}
+  local new_nvim_argv = {} --- @type string[]
   local len = #prepend_argv
   for i = 1, len do
     new_nvim_argv[i] = prepend_argv[i]
@@ -91,10 +91,13 @@ if prepend_argv then
   module.prepend_argv = prepend_argv
 end
 
-local session, loop_running, last_error, method_error
+local session --- @type test.Session?
+local loop_running --- @type boolean?
+local last_error --- @type string?
+local method_error --- @type string?
 
 if not is_os('win') then
-  local sigpipe_handler = uv.new_signal()
+  local sigpipe_handler = assert(uv.new_signal())
   uv.signal_start(sigpipe_handler, 'sigpipe', function()
     print('warning: got SIGPIPE signal. Likely related to a crash in nvim')
   end)
@@ -108,10 +111,15 @@ function module.set_session(s)
   session = s
 end
 
+--- @param method string
+--- @param ... any
+--- @return any
 function module.request(method, ...)
+  assert(session)
   local status, rv = session:request(method, ...)
   if not status then
     if loop_running then
+      --- @type string
       last_error = rv[2]
       session:stop()
     else
@@ -121,12 +129,18 @@ function module.request(method, ...)
   return rv
 end
 
+--- @param method string
+--- @param ... any
+--- @return any
 function module.request_lua(method, ...)
   return module.exec_lua([[return vim.api[...](select(2, ...))]], method, ...)
 end
 
+--- @param timeout? integer
+--- @return string?
 function module.next_msg(timeout)
-  return session:next_message(timeout and timeout or 10000)
+  assert(session)
+  return session:next_message(timeout or 10000)
 end
 
 function module.expect_twostreams(msgs1, msgs2)
@@ -164,6 +178,7 @@ function module.expect_msg_seq(...)
     error('invalid args')
   end
   local ignore = arg1['ignore'] and arg1['ignore'] or {}
+  --- @type string[]
   local seqs = arg1['seqs'] and arg1['seqs'] or { ... }
   if type(ignore) ~= 'table' then
     error("'ignore' arg must be a list of strings")
@@ -213,6 +228,7 @@ function module.expect_msg_seq(...)
     local message = result
     if type(result) == 'table' then
       -- 'eq' returns several things
+      --- @type string
       message = result.message
     end
     final_error = cat_err(final_error, message)
@@ -234,8 +250,16 @@ function module.set_method_error(err)
   method_error = err
 end
 
+--- @param lsession test.Session
+--- @param request_cb function
+--- @param notification_cb function
+--- @param setup_cb function
+--- @param timeout integer
+--- @return {[1]: integer, [2]: string}
 function module.run_session(lsession, request_cb, notification_cb, setup_cb, timeout)
-  local on_request, on_notification, on_setup
+  local on_request --- @type function?
+  local on_notification --- @type function?
+  local on_setup --- @type function?
 
   if request_cb then
     function on_request(method, args)
@@ -273,11 +297,12 @@ function module.run_session(lsession, request_cb, notification_cb, setup_cb, tim
 end
 
 function module.run(request_cb, notification_cb, setup_cb, timeout)
+  assert(session)
   return module.run_session(session, request_cb, notification_cb, setup_cb, timeout)
 end
 
 function module.stop()
-  session:stop()
+  assert(session):stop()
 end
 
 function module.nvim_prog_abs()
@@ -301,6 +326,7 @@ function module.expect_exit(fn_or_timeout, ...)
       eof_err_msg,
       module.pcall_err(function(timeout, fn, ...)
         fn(...)
+        assert(session)
         while session:next_message(timeout) do
         end
         if session.eof_err then
@@ -311,26 +337,18 @@ function module.expect_exit(fn_or_timeout, ...)
   end
 end
 
--- Evaluates a Vimscript expression.
--- Fails on Vimscript error, but does not update v:errmsg.
-function module.eval(expr)
-  return module.request('nvim_eval', expr)
-end
-
--- Executes a Vimscript function via RPC.
--- Fails on Vimscript error, but does not update v:errmsg.
-function module.call(name, ...)
-  return module.request('nvim_call_function', name, { ... })
-end
-
--- Executes a Vimscript function via Lua.
--- Fails on Vimscript error, but does not update v:errmsg.
+--- Executes a Vimscript function via Lua.
+--- Fails on Vimscript error, but does not update v:errmsg.
+--- @param name string
+--- @param ... any
+--- @return any
 function module.call_lua(name, ...)
   return module.exec_lua([[return vim.call(...)]], name, ...)
 end
 
--- Sends user input to Nvim.
--- Does not fail on Vimscript error, but v:errmsg will be updated.
+--- Sends user input to Nvim.
+--- Does not fail on Vimscript error, but v:errmsg will be updated.
+--- @param input string
 local function nvim_feed(input)
   while #input > 0 do
     local written = module.request('nvim_input', input)
@@ -342,22 +360,27 @@ local function nvim_feed(input)
   end
 end
 
+--- @param ... string
 function module.feed(...)
   for _, v in ipairs({ ... }) do
     nvim_feed(dedent(v))
   end
 end
 
+--- @param ... string
 function module.rawfeed(...)
   for _, v in ipairs({ ... }) do
     nvim_feed(dedent(v))
   end
 end
 
+---@param ... string[]?
+---@return string[]
 function module.merge_args(...)
   local i = 1
-  local argv = {}
+  local argv = {} --- @type string[]
   for anum = 1, select('#', ...) do
+    --- @type string[]?
     local args = select(anum, ...)
     if args then
       for _, arg in ipairs(args) do
@@ -369,26 +392,29 @@ function module.merge_args(...)
   return argv
 end
 
---  Removes Nvim startup args from `args` matching items in `args_rm`.
---
---  - Special case: "-u", "-i", "--cmd" are treated specially: their "values" are also removed.
---  - Special case: "runtimepath" will remove only { '--cmd', 'set runtimepath^=…', }
---
---  Example:
---      args={'--headless', '-u', 'NONE'}
---      args_rm={'--cmd', '-u'}
---  Result:
---      {'--headless'}
---
---  All matching cases are removed.
---
---  Example:
---      args={'--cmd', 'foo', '-N', '--cmd', 'bar'}
---      args_rm={'--cmd', '-u'}
---  Result:
---      {'-N'}
+--- Removes Nvim startup args from `args` matching items in `args_rm`.
+---
+--- - Special case: "-u", "-i", "--cmd" are treated specially: their "values" are also removed.
+--- - Special case: "runtimepath" will remove only { '--cmd', 'set runtimepath^=…', }
+---
+--- Example:
+---     args={'--headless', '-u', 'NONE'}
+---     args_rm={'--cmd', '-u'}
+--- Result:
+---     {'--headless'}
+---
+--- All matching cases are removed.
+---
+--- Example:
+---     args={'--cmd', 'foo', '-N', '--cmd', 'bar'}
+---     args_rm={'--cmd', '-u'}
+--- Result:
+---     {'-N'}
+--- @param args string[]
+--- @param args_rm string[]
+--- @return string[]
 local function remove_args(args, args_rm)
-  local new_args = {}
+  local new_args = {} --- @type string[]
   local skip_following = { '-u', '-i', '-c', '--cmd', '-s', '--listen' }
   if not args_rm or #args_rm == 0 then
     return { unpack(args) }
@@ -433,7 +459,12 @@ function module.check_close()
   session = nil
 end
 
---- @param io_extra used for stdin_fd, see :help ui-option
+--- @param argv string[]
+--- @param merge boolean?
+--- @param env string[]?
+--- @param keep boolean
+--- @param io_extra uv.uv_pipe_t? used for stdin_fd, see :help ui-option
+--- @return test.Session
 function module.spawn(argv, merge, env, keep, io_extra)
   if not keep then
     module.check_close()
@@ -469,16 +500,27 @@ function module.clear(...)
   return module.get_session()
 end
 
--- same params as clear, but does returns the session instead
--- of replacing the default session
+--- same params as clear, but does returns the session instead
+--- of replacing the default session
+--- @return test.Session
 function module.spawn_argv(keep, ...)
   local argv, env, io_extra = module.new_argv(...)
   return module.spawn(argv, nil, env, keep, io_extra)
 end
 
--- Builds an argument list for use in clear().
---
----@see clear() for parameters.
+--- @class test.new_argv.Opts
+--- @field args? string[]
+--- @field args_rm? string[]
+--- @field env? table<string,string>
+--- @field io_extra? uv.uv_pipe_t
+
+--- Builds an argument list for use in clear().
+---
+--- @see clear() for parameters.
+--- @param ... string
+--- @return string[]
+--- @return string[]?
+--- @return uv.uv_pipe_t?
 function module.new_argv(...)
   local args = { unpack(module.nvim_argv) }
   table.insert(args, '--headless')
@@ -487,16 +529,17 @@ function module.new_argv(...)
     table.insert(args, '--listen')
     table.insert(args, _G._nvim_test_id)
   end
-  local new_args
-  local io_extra
-  local env = nil
+  local new_args --- @type string[]
+  local io_extra --- @type uv.uv_pipe_t?
+  local env --- @type string[]?
+  --- @type test.new_argv.Opts|string
   local opts = select(1, ...)
   if type(opts) ~= 'table' then
     new_args = { ... }
   else
     args = remove_args(args, opts.args_rm)
     if opts.env then
-      local env_opt = {}
+      local env_opt = {} --- @type table<string,string>
       for k, v in pairs(opts.env) do
         assert(type(k) == 'string')
         assert(type(v) == 'string')
@@ -535,6 +578,7 @@ function module.new_argv(...)
   return args, env, io_extra
 end
 
+--- @param ... string
 function module.insert(...)
   nvim_feed('i')
   for _, v in ipairs({ ... }) do
@@ -544,8 +588,9 @@ function module.insert(...)
   nvim_feed('<ESC>')
 end
 
--- Executes an ex-command by user input. Because nvim_input() is used, Vimscript
--- errors will not manifest as client (lua) errors. Use command() for that.
+--- Executes an ex-command by user input. Because nvim_input() is used, Vimscript
+--- errors will not manifest as client (lua) errors. Use command() for that.
+--- @param ... string
 function module.feed_command(...)
   for _, v in ipairs({ ... }) do
     if v:sub(1, 1) ~= '/' then
@@ -598,8 +643,10 @@ function module.set_shell_powershell(fake)
 end
 
 function module.create_callindex(func)
-  local table = {}
-  setmetatable(table, {
+  return setmetatable({}, {
+    --- @param tbl table<any,function>
+    --- @param arg1 string
+    --- @return function
     __index = function(tbl, arg1)
       local ret = function(...)
         return func(arg1, ...)
@@ -608,36 +655,34 @@ function module.create_callindex(func)
       return ret
     end,
   })
-  return table
 end
 
-local function ui(method, ...)
-  return module.request('nvim_ui_' .. method, ...)
+--- @param method string
+--- @param ... any
+function module.nvim_async(method, ...)
+  assert(session):notify(method, ...)
 end
 
-function module.nvim_async(method, ...)
-  session:notify('nvim_' .. method, ...)
+--- Executes a Vimscript function via RPC.
+--- Fails on Vimscript error, but does not update v:errmsg.
+--- @param name string
+--- @param ... any
+--- @return any
+function module.call(name, ...)
+  return module.request('nvim_call_function', name, { ... })
 end
 
 module.async_meths = module.create_callindex(module.nvim_async)
-module.uimeths = module.create_callindex(ui)
-
-local function create_bridge(request, call)
-  local function nvim(method, ...)
-    if vim.startswith(method, 'nvim_') then
-      return request(method, ...)
-    end
-    return request('nvim_' .. method, ...)
-  end
 
-  return {
-    fn = module.create_callindex(call),
-    api = module.create_callindex(nvim),
-  }
-end
+module.rpc = {
+  fn = module.create_callindex(module.call),
+  api = module.create_callindex(module.request),
+}
 
-module.rpc = create_bridge(module.request, module.call)
-module.lua = create_bridge(module.request_lua, module.call_lua)
+module.lua = {
+  fn = module.create_callindex(module.call_lua),
+  api = module.create_callindex(module.request_lua),
+}
 
 module.describe_lua_and_rpc = function(describe)
   return function(what, tests)
@@ -657,6 +702,7 @@ module.api = vim.api
 module.fn = vim.fn
 
 for name, fns in pairs(module.rpc) do
+  --- @diagnostic disable-next-line:no-unknown
   module[name] = fns
 end
 
@@ -664,10 +710,14 @@ end
 -- v:errmsg will not be updated.
 module.command = module.api.nvim_command
 
+-- Evaluates a Vimscript expression.
+-- Fails on Vimscript error, but does not update v:errmsg.
+module.eval = module.api.nvim_eval
+
 function module.poke_eventloop()
   -- Execute 'nvim_eval' (a deferred function) to
   -- force at least one main_loop iteration
-  session:request('nvim_eval', '1')
+  module.api.nvim_eval('1')
 end
 
 function module.buf_lines(bufnr)
@@ -689,6 +739,10 @@ function module.expect_any(contents)
   return ok(nil ~= string.find(module.curbuf_contents(), contents, 1, true))
 end
 
+--- @param expected any[]
+--- @param received any[]
+--- @param kind string
+--- @return any
 function module.expect_events(expected, received, kind)
   if not pcall(eq, expected, received) then
     local msg = 'unexpected ' .. kind .. ' received.\n\n'
@@ -728,6 +782,7 @@ function module.assert_visible(bufnr, visible)
   end
 end
 
+--- @param path string
 local function do_rmdir(path)
   local stat = uv.fs_stat(path)
   if stat == nil then
@@ -795,14 +850,17 @@ function module.exc_exec(cmd)
   return ret
 end
 
+--- @param cond boolean
+--- @param reason string
+--- @return boolean
 function module.skip(cond, reason)
   if cond then
+    --- @type fun(reason: string)
     local pending = getfenv(2).pending
     pending(reason or 'FIXME')
     return true
-  else
-    return false
   end
+  return false
 end
 
 -- Calls pending() and returns `true` if the system is too slow to
@@ -825,6 +883,8 @@ function module.exec(code)
   module.api.nvim_exec2(code, {})
 end
 
+--- @param code string
+--- @return string
 function module.exec_capture(code)
   return module.api.nvim_exec2(code, { output = true }).output
 end
@@ -832,7 +892,7 @@ end
 --- @param code string
 --- @return any
 function module.exec_lua(code, ...)
-  return module.api.exec_lua(code, { ... })
+  return module.api.nvim_exec_lua(code, { ... })
 end
 
 function module.get_pathsep()
@@ -871,19 +931,24 @@ function module.new_pipename()
   return pipename
 end
 
+--- @param provider string
+--- @return string|false?
 function module.missing_provider(provider)
   if provider == 'ruby' or provider == 'node' or provider == 'perl' then
+    --- @type string?
     local e = module.fn['provider#' .. provider .. '#Detect']()[2]
     return e ~= '' and e or false
   elseif provider == 'python' or provider == 'python3' then
     local py_major_version = (provider == 'python3' and 3 or 2)
+    --- @type string?
     local e = module.fn['provider#pythonx#Detect'](py_major_version)[2]
     return e ~= '' and e or false
-  else
-    assert(false, 'Unknown provider: ' .. provider)
   end
+  assert(false, 'Unknown provider: ' .. provider)
 end
 
+--- @param obj string|table
+--- @return any
 function module.alter_slashes(obj)
   if not is_os('win') then
     return obj
@@ -892,14 +957,14 @@ function module.alter_slashes(obj)
     local ret = obj:gsub('/', '\\')
     return ret
   elseif type(obj) == 'table' then
-    local ret = {}
+    --- @cast obj table<any,any>
+    local ret = {} --- @type table<any,any>
     for k, v in pairs(obj) do
       ret[k] = module.alter_slashes(v)
     end
     return ret
-  else
-    assert(false, 'expected string or table of strings, got ' .. type(obj))
   end
+  assert(false, 'expected string or table of strings, got ' .. type(obj))
 end
 
 local load_factor = 1
@@ -909,18 +974,25 @@ if global_helpers.is_ci() then
   module.request('nvim_command', 'source test/old/testdir/load.vim')
   load_factor = module.request('nvim_eval', 'g:test_load_factor')
 end
+
+--- @param num number
+--- @return number
 function module.load_adjust(num)
   return math.ceil(num * load_factor)
 end
 
+--- @param ctx table<string,any>
+--- @return table
 function module.parse_context(ctx)
-  local parsed = {}
+  local parsed = {} --- @type table<string,any>
   for _, item in ipairs({ 'regs', 'jumps', 'bufs', 'gvars' }) do
+    --- @param v any
     parsed[item] = vim.tbl_filter(function(v)
       return type(v) == 'table'
     end, module.call('msgpackparse', ctx[item]))
   end
   parsed['bufs'] = parsed['bufs'][1]
+  --- @param v any
   return vim.tbl_map(function(v)
     if #v == 0 then
       return nil
@@ -931,10 +1003,12 @@ end
 
 function module.add_builddir_to_rtp()
   -- Add runtime from build dir for doc/tags (used with :help).
-  module.command(string.format([[set rtp+=%s/runtime]], module.test_build_dir))
+  module.command(string.format([[set rtp+=%s/runtime]], module.paths.test_build_dir))
 end
 
--- Kill (reap) a process by PID.
+--- Kill (reap) a process by PID.
+--- @param pid string
+--- @return boolean?
 function module.os_kill(pid)
   return os.execute(
     (
@@ -944,7 +1018,9 @@ function module.os_kill(pid)
   )
 end
 
--- Create folder with non existing parents
+--- Create folder with non existing parents
+--- @param path string
+--- @return boolean?
 function module.mkdir_p(path)
   return os.execute((is_os('win') and 'mkdir ' .. path or 'mkdir -p ' .. path))
 end
diff --git a/test/functional/lua/fs_spec.lua b/test/functional/lua/fs_spec.lua
index 66ba0f71f2..6821fe3c5e 100644
--- a/test/functional/lua/fs_spec.lua
+++ b/test/functional/lua/fs_spec.lua
@@ -6,8 +6,8 @@ local eq = helpers.eq
 local mkdir_p = helpers.mkdir_p
 local rmdir = helpers.rmdir
 local nvim_dir = helpers.nvim_dir
-local test_build_dir = helpers.test_build_dir
-local test_source_path = helpers.test_source_path
+local test_build_dir = helpers.paths.test_build_dir
+local test_source_path = helpers.paths.test_source_path
 local nvim_prog = helpers.nvim_prog
 local is_os = helpers.is_os
 local mkdir = helpers.mkdir
diff --git a/test/functional/lua/luaeval_spec.lua b/test/functional/lua/luaeval_spec.lua
index 6ed7af6b6e..171d37ba55 100644
--- a/test/functional/lua/luaeval_spec.lua
+++ b/test/functional/lua/luaeval_spec.lua
@@ -162,7 +162,7 @@ describe('luaeval()', function()
     return sp('map', '[' .. val .. ']')
   end
   local function luaevalarg(argexpr, expr)
-    return eval(([=[
+    return eval((([=[
       [
         extend(g:, {'_ret': luaeval(%s, %s)})._ret,
         type(g:_ret)==type({})&&has_key(g:_ret, '_TYPE')
@@ -172,7 +172,7 @@ describe('luaeval()', function()
           get(g:_ret, '_VAL', g:_ret)
         ]
         : [0, g:_ret]][1]
-    ]=]):format(expr or '"_A"', argexpr):gsub('\n', ''))
+    ]=]):format(expr or '"_A"', argexpr):gsub('\n', '')))
   end
 
   it('correctly passes special dictionaries', function()
diff --git a/test/functional/shada/merging_spec.lua b/test/functional/shada/merging_spec.lua
index 94e0ee6e82..1b5c0eab5d 100644
--- a/test/functional/shada/merging_spec.lua
+++ b/test/functional/shada/merging_spec.lua
@@ -525,7 +525,7 @@ describe('ShaDa marks support code', function()
     local found = 0
     for _, v in ipairs(read_shada_file(shada_fname)) do
       if v.type == 7 and v.value.f == mock_file_path .. '-' then
-        print(require('test.helpers').format_luav(v))
+        print(require('test.format_string').format_luav(v))
         found = found + 1
       end
     end
diff --git a/test/functional/shada/shada_spec.lua b/test/functional/shada/shada_spec.lua
index 2942beab2f..6eb318015d 100644
--- a/test/functional/shada/shada_spec.lua
+++ b/test/functional/shada/shada_spec.lua
@@ -7,7 +7,7 @@ local is_os = helpers.is_os
 local skip = helpers.skip
 
 local uv = vim.uv
-local paths = require('test.cmakeconfig.paths')
+local paths = helpers.paths
 
 local shada_helpers = require('test.functional.shada.helpers')
 local reset, clear, get_shada_rw =
diff --git a/test/functional/terminal/channel_spec.lua b/test/functional/terminal/channel_spec.lua
index 2b39c93f14..9615534c87 100644
--- a/test/functional/terminal/channel_spec.lua
+++ b/test/functional/terminal/channel_spec.lua
@@ -151,7 +151,7 @@ describe('no crash when TermOpen autocommand', function()
 
   it('processes job exit event when using termopen()', function()
     command([[autocmd TermOpen * call input('')]])
-    async_meths.command('terminal foobar')
+    async_meths.nvim_command('terminal foobar')
     screen:expect {
       grid = [[
                                                                   |
@@ -181,7 +181,7 @@ describe('no crash when TermOpen autocommand', function()
 
   it('wipes buffer and processes events when using termopen()', function()
     command([[autocmd TermOpen * bwipe! | call input('')]])
-    async_meths.command('terminal foobar')
+    async_meths.nvim_command('terminal foobar')
     screen:expect {
       grid = [[
                                                                   |
@@ -202,7 +202,7 @@ describe('no crash when TermOpen autocommand', function()
 
   it('wipes buffer and processes events when using nvim_open_term()', function()
     command([[autocmd TermOpen * bwipe! | call input('')]])
-    async_meths.open_term(0, {})
+    async_meths.nvim_open_term(0, {})
     screen:expect {
       grid = [[
                                                                   |
diff --git a/test/functional/ui/messages_spec.lua b/test/functional/ui/messages_spec.lua
index 4f95cd909c..9d1b6163d2 100644
--- a/test/functional/ui/messages_spec.lua
+++ b/test/functional/ui/messages_spec.lua
@@ -7,7 +7,7 @@ local command = helpers.command
 local set_method_error = helpers.set_method_error
 local api = helpers.api
 local async_meths = helpers.async_meths
-local test_build_dir = helpers.test_build_dir
+local test_build_dir = helpers.paths.test_build_dir
 local nvim_prog = helpers.nvim_prog
 local exec = helpers.exec
 local exec_capture = helpers.exec_capture
@@ -1039,7 +1039,7 @@ stack traceback:
   end)
 
   it('supports nvim_echo messages with multiple attrs', function()
-    async_meths.echo(
+    async_meths.nvim_echo(
       { { 'wow, ', 'Search' }, { 'such\n\nvery ', 'ErrorMsg' }, { 'color', 'LineNr' } },
       true,
       {}
@@ -1403,7 +1403,7 @@ vimComment     xxx match /\s"[^\-:.%#=*].*$/ms=s+1,lc=1  excludenl contains=@vim
   end)
 
   it('supports nvim_echo messages with multiple attrs', function()
-    async_meths.echo(
+    async_meths.nvim_echo(
       { { 'wow, ', 'Search' }, { 'such\n\nvery ', 'ErrorMsg' }, { 'color', 'LineNr' } },
       true,
       {}
@@ -1521,7 +1521,7 @@ vimComment     xxx match /\s"[^\-:.%#=*].*$/ms=s+1,lc=1  excludenl contains=@vim
   end)
 
   it('consecutive calls to win_move_statusline() work after multiline message #21014', function()
-    async_meths.exec(
+    async_meths.nvim_exec(
       [[
       echo "\n"
       call win_move_statusline(0, -4)
@@ -2196,7 +2196,7 @@ aliquip ex ea commodo consequat.]]
     }
 
     -- not processed while command is executing
-    async_meths.ui_try_resize(35, 5)
+    async_meths.nvim_ui_try_resize(35, 5)
 
     -- TODO(bfredl): ideally it should be processed just
     -- before the "press ENTER" prompt though
diff --git a/test/functional/ui/popupmenu_spec.lua b/test/functional/ui/popupmenu_spec.lua
index b74a15d56f..1f7d187016 100644
--- a/test/functional/ui/popupmenu_spec.lua
+++ b/test/functional/ui/popupmenu_spec.lua
@@ -2527,7 +2527,7 @@ describe('builtin popupmenu', function()
         ]])
       end
       feed('<C-E>')
-      async_meths.call_function('input', { '', '', 'sign' })
+      async_meths.nvim_call_function('input', { '', '', 'sign' })
       if multigrid then
         screen:expect {
           grid = [[
diff --git a/test/functional/vimscript/ctx_functions_spec.lua b/test/functional/vimscript/ctx_functions_spec.lua
index b8f9bbc92d..dc60a474f3 100644
--- a/test/functional/vimscript/ctx_functions_spec.lua
+++ b/test/functional/vimscript/ctx_functions_spec.lua
@@ -314,13 +314,13 @@ describe('context functions', function()
       }
 
       local with_jumps = {
-        ['jumps'] = eval(([[
+        ['jumps'] = eval((([[
         filter(map(add(
         getjumplist()[0], { 'bufnr': bufnr('%'), 'lnum': getcurpos()[1] }),
         'filter(
         { "f": expand("#".v:val.bufnr.":p"), "l": v:val.lnum },
         { k, v -> k != "l" || v != 1 })'), '!empty(v:val.f)')
-        ]]):gsub('\n', '')),
+        ]]):gsub('\n', ''))),
       }
 
       local with_bufs = {
diff --git a/test/functional/vimscript/input_spec.lua b/test/functional/vimscript/input_spec.lua
index 6dd22078d6..b749d5a7f0 100644
--- a/test/functional/vimscript/input_spec.lua
+++ b/test/functional/vimscript/input_spec.lua
@@ -414,19 +414,19 @@ describe('confirm()', function()
     -- screen:expect() calls are needed to avoid feeding input too early
     screen:expect({ any = '%[No Name%]' })
 
-    async_meths.command([[let a = confirm('Press O to proceed')]])
+    async_meths.nvim_command([[let a = confirm('Press O to proceed')]])
     screen:expect({ any = '{CONFIRM:.+: }' })
     feed('o')
     screen:expect({ any = '%[No Name%]' })
     eq(1, api.nvim_get_var('a'))
 
-    async_meths.command([[let a = 'Are you sure?'->confirm("&Yes\n&No")]])
+    async_meths.nvim_command([[let a = 'Are you sure?'->confirm("&Yes\n&No")]])
     screen:expect({ any = '{CONFIRM:.+: }' })
     feed('y')
     screen:expect({ any = '%[No Name%]' })
     eq(1, api.nvim_get_var('a'))
 
-    async_meths.command([[let a = confirm('Are you sure?', "&Yes\n&No")]])
+    async_meths.nvim_command([[let a = confirm('Are you sure?', "&Yes\n&No")]])
     screen:expect({ any = '{CONFIRM:.+: }' })
     feed('n')
     screen:expect({ any = '%[No Name%]' })
@@ -435,26 +435,26 @@ describe('confirm()', function()
     -- Not possible to match Vim's CTRL-C test here as CTRL-C always sets got_int in Nvim.
 
     -- confirm() should return 0 when pressing ESC.
-    async_meths.command([[let a = confirm('Are you sure?', "&Yes\n&No")]])
+    async_meths.nvim_command([[let a = confirm('Are you sure?', "&Yes\n&No")]])
     screen:expect({ any = '{CONFIRM:.+: }' })
     feed('<Esc>')
     screen:expect({ any = '%[No Name%]' })
     eq(0, api.nvim_get_var('a'))
 
     -- Default choice is returned when pressing <CR>.
-    async_meths.command([[let a = confirm('Are you sure?', "&Yes\n&No")]])
+    async_meths.nvim_command([[let a = confirm('Are you sure?', "&Yes\n&No")]])
     screen:expect({ any = '{CONFIRM:.+: }' })
     feed('<CR>')
     screen:expect({ any = '%[No Name%]' })
     eq(1, api.nvim_get_var('a'))
 
-    async_meths.command([[let a = confirm('Are you sure?', "&Yes\n&No", 2)]])
+    async_meths.nvim_command([[let a = confirm('Are you sure?', "&Yes\n&No", 2)]])
     screen:expect({ any = '{CONFIRM:.+: }' })
     feed('<CR>')
     screen:expect({ any = '%[No Name%]' })
     eq(2, api.nvim_get_var('a'))
 
-    async_meths.command([[let a = confirm('Are you sure?', "&Yes\n&No", 0)]])
+    async_meths.nvim_command([[let a = confirm('Are you sure?', "&Yes\n&No", 0)]])
     screen:expect({ any = '{CONFIRM:.+: }' })
     feed('<CR>')
     screen:expect({ any = '%[No Name%]' })
@@ -462,7 +462,9 @@ describe('confirm()', function()
 
     -- Test with the {type} 4th argument
     for _, type in ipairs({ 'Error', 'Question', 'Info', 'Warning', 'Generic' }) do
-      async_meths.command(([[let a = confirm('Are you sure?', "&Yes\n&No", 1, '%s')]]):format(type))
+      async_meths.nvim_command(
+        ([[let a = confirm('Are you sure?', "&Yes\n&No", 1, '%s')]]):format(type)
+      )
       screen:expect({ any = '{CONFIRM:.+: }' })
       feed('y')
       screen:expect({ any = '%[No Name%]' })
@@ -518,7 +520,7 @@ describe('confirm()', function()
     feed(':call nvim_command("edit x")<cr>')
     check_and_clear(':call nvim_command("edit |\n')
 
-    async_meths.command('edit x')
+    async_meths.nvim_command('edit x')
     check_and_clear('                         |\n')
   end)
 end)
diff --git a/test/functional/vimscript/timer_spec.lua b/test/functional/vimscript/timer_spec.lua
index 3f53c21e7a..046d451888 100644
--- a/test/functional/vimscript/timer_spec.lua
+++ b/test/functional/vimscript/timer_spec.lua
@@ -1,7 +1,7 @@
 local helpers = require('test.functional.helpers')(after_each)
 local Screen = require('test.functional.ui.screen')
 local feed, eq, eval, ok = helpers.feed, helpers.eq, helpers.eval, helpers.ok
-local source, nvim_async, run = helpers.source, helpers.nvim_async, helpers.run
+local source, async_meths, run = helpers.source, helpers.async_meths, helpers.run
 local clear, command, fn = helpers.clear, helpers.command, helpers.fn
 local exc_exec = helpers.exc_exec
 local api = helpers.api
@@ -52,9 +52,9 @@ describe('timers', function()
       endfunc
     ]])
     eval("timer_start(10, 'MyHandler', {'repeat': -1})")
-    nvim_async('command', 'sleep 10')
+    async_meths.nvim_command('sleep 10')
     eq(-1, eval('g:val')) -- timer did nothing yet.
-    nvim_async('command', 'let g:val = 0')
+    async_meths.nvim_command('let g:val = 0')
     run(nil, nil, nil, load_adjust(20))
     retry(nil, nil, function()
       eq(2, eval('g:val'))
@@ -70,7 +70,7 @@ describe('timers', function()
   end)
 
   it('can be started during sleep', function()
-    nvim_async('command', 'sleep 10')
+    async_meths.nvim_command('sleep 10')
     -- this also tests that remote requests works during sleep
     eq(0, eval("[timer_start(10, 'MyHandler', {'repeat': 2}), g:val][1]"))
     run(nil, nil, nil, load_adjust(20))
@@ -94,7 +94,7 @@ describe('timers', function()
 
   it('are triggered in blocking getchar() call', function()
     command("call timer_start(5, 'MyHandler', {'repeat': -1})")
-    nvim_async('command', 'let g:val = 0 | let g:c = getchar()')
+    async_meths.nvim_command('let g:val = 0 | let g:c = getchar()')
     retry(nil, nil, function()
       local val = eval('g:val')
       ok(val >= 2, '>= 2', tostring(val))
@@ -128,8 +128,10 @@ describe('timers', function()
         redraw
       endfunc
     ]])
-    nvim_async('command', 'let g:c2 = getchar()')
-    nvim_async('command', 'call timer_start(' .. load_adjust(100) .. ", 'AddItem', {'repeat': -1})")
+    async_meths.nvim_command('let g:c2 = getchar()')
+    async_meths.nvim_command(
+      'call timer_start(' .. load_adjust(100) .. ", 'AddItem', {'repeat': -1})"
+    )
 
     screen:expect([[
       ^ITEM 1                                  |
@@ -137,7 +139,7 @@ describe('timers', function()
       {1:~                                       }|*3
                                               |
     ]])
-    nvim_async('command', 'let g:cont = 1')
+    async_meths.nvim_command('let g:cont = 1')
 
     screen:expect([[
       ^ITEM 1                                  |
diff --git a/test/helpers.lua b/test/helpers.lua
index 83d7a0ece6..24ccead8b2 100644
--- a/test/helpers.lua
+++ b/test/helpers.lua
@@ -18,15 +18,14 @@ end
 
 --- @class test.helpers
 local module = {
-  REMOVE_THIS = {},
+  paths = Paths,
 }
 
 --- @param p string
 --- @return string
 local function relpath(p)
   p = vim.fs.normalize(p)
-  local cwd = uv.cwd()
-  return p:gsub('^' .. cwd)
+  return (p:gsub('^' .. uv.cwd, ''))
 end
 
 --- @param path string
@@ -42,41 +41,34 @@ function module.isdir(path)
   return stat.type == 'directory'
 end
 
---- @param path string
---- @return boolean
-function module.isfile(path)
-  if not path then
-    return false
-  end
-  local stat = uv.fs_stat(path)
-  if not stat then
-    return false
-  end
-  return stat.type == 'file'
-end
-
+--- @param ... string|string[]
 --- @return string
 function module.argss_to_cmd(...)
-  local cmd = ''
+  local cmd = {} --- @type string[]
   for i = 1, select('#', ...) do
     local arg = select(i, ...)
     if type(arg) == 'string' then
-      cmd = cmd .. ' ' .. shell_quote(arg)
+      cmd[#cmd + 1] = shell_quote(arg)
     else
+      --- @cast arg string[]
       for _, subarg in ipairs(arg) do
-        cmd = cmd .. ' ' .. shell_quote(subarg)
+        cmd[#cmd + 1] = shell_quote(subarg)
       end
     end
   end
-  return cmd
+  return table.concat(cmd, ' ')
 end
 
 function module.popen_r(...)
   return io.popen(module.argss_to_cmd(...), 'r')
 end
 
--- Calls fn() until it succeeds, up to `max` times or until `max_ms`
--- milliseconds have passed.
+--- Calls fn() until it succeeds, up to `max` times or until `max_ms`
+--- milliseconds have passed.
+--- @param max integer?
+--- @param max_ms integer?
+--- @param fn function
+--- @return any
 function module.retry(max, max_ms, fn)
   luaassert(max == nil or max > 0)
   luaassert(max_ms == nil or max_ms > 0)
@@ -84,6 +76,7 @@ function module.retry(max, max_ms, fn)
   local timeout = (max_ms and max_ms or 10000)
   local start_time = uv.now()
   while true do
+    --- @type boolean, any
     local status, result = pcall(fn)
     if status then
       return result
@@ -133,6 +126,9 @@ function module.fail(msg)
   return luaassert.epicfail(msg)
 end
 
+--- @param pat string
+--- @param actual string
+--- @return boolean
 function module.matches(pat, actual)
   if nil ~= string.match(actual, pat) then
     return true
@@ -182,10 +178,16 @@ end
 --- Asserts that `pat` does NOT match any line in the tail of `logfile`.
 ---
 --- @see assert_log
+--- @param pat (string) Lua pattern to match lines in the log file
+--- @param logfile? (string) Full path to log file (default=$NVIM_LOG_FILE)
+--- @param nrlines? (number) Search up to this many log lines
 function module.assert_nolog(pat, logfile, nrlines)
   return module.assert_log(pat, logfile, nrlines, true)
 end
 
+--- @param fn fun(...): any
+--- @param ... any
+--- @return boolean, any
 function module.pcall(fn, ...)
   luaassert(type(fn) == 'function')
   local status, rv = pcall(fn, ...)
@@ -233,6 +235,8 @@ end
 --    -- Match Lua pattern.
 --    matches('e[or]+$', pcall_err(function(a, b) error('some error') end, 'arg1', 'arg2'))
 --
+--- @param fn function
+--- @return string
 function module.pcall_err_withfile(fn, ...)
   luaassert(type(fn) == 'function')
   local status, rv = module.pcall(fn, ...)
@@ -242,19 +246,29 @@ function module.pcall_err_withfile(fn, ...)
   return rv
 end
 
+--- @param fn function
+--- @param ... any
+--- @return string
 function module.pcall_err_withtrace(fn, ...)
   local errmsg = module.pcall_err_withfile(fn, ...)
 
-  return errmsg
-    :gsub('^%.%.%./helpers%.lua:0: ', '')
-    :gsub('^Error executing lua:- ', '')
-    :gsub('^%[string "<nvim>"%]:0: ', '')
+  return (
+    errmsg
+      :gsub('^%.%.%./helpers%.lua:0: ', '')
+      :gsub('^Error executing lua:- ', '')
+      :gsub('^%[string "<nvim>"%]:0: ', '')
+  )
 end
 
-function module.pcall_err(...)
-  return module.remove_trace(module.pcall_err_withtrace(...))
+--- @param fn function
+--- @param ... any
+--- @return string
+function module.pcall_err(fn, ...)
+  return module.remove_trace(module.pcall_err_withtrace(fn, ...))
 end
 
+--- @param s string
+--- @return string
 function module.remove_trace(s)
   return (s:gsub('\n%s*stack traceback:.*', ''))
 end
@@ -264,9 +278,9 @@ end
 -- exc_re:        exclude pattern(s) (string or table)
 function module.glob(initial_path, re, exc_re)
   exc_re = type(exc_re) == 'table' and exc_re or { exc_re }
-  local paths_to_check = { initial_path }
-  local ret = {}
-  local checked_files = {}
+  local paths_to_check = { initial_path } --- @type string[]
+  local ret = {} --- @type string[]
+  local checked_files = {} --- @type table<string,true>
   local function is_excluded(path)
     for _, pat in pairs(exc_re) do
       if path:match(pat) then
@@ -313,7 +327,7 @@ function module.check_logs()
         local file = log_dir .. '/' .. tail
         local fd = assert(io.open(file))
         local start_msg = ('='):rep(20) .. ' File ' .. file .. ' ' .. ('='):rep(20)
-        local lines = {}
+        local lines = {} --- @type string[]
         local warning_line = 0
         for line in fd:lines() do
           local cur_warning_line = check_logs_useless_lines[line]
@@ -325,6 +339,7 @@ function module.check_logs()
         end
         fd:close()
         if #lines > 0 then
+          --- @type boolean?, file*?
           local status, f
           local out = io.stdout
           if os.getenv('SYMBOLIZER') then
@@ -332,6 +347,7 @@ function module.check_logs()
           end
           out:write(start_msg .. '\n')
           if status then
+            assert(f)
             for line in f:lines() do
               out:write('= ' .. line .. '\n')
             end
@@ -353,10 +369,7 @@ function module.check_logs()
 end
 
 function module.sysname()
-  local platform = uv.os_uname()
-  if platform and platform.sysname then
-    return platform.sysname:lower()
-  end
+  return uv.os_uname().sysname:lower()
 end
 
 function module.is_os(s)
@@ -372,26 +385,15 @@ function module.is_os(s)
   )
 end
 
-function module.is_arch(s)
-  local machine = uv.os_uname().machine
-  if s == 'arm64' or s == 'aarch64' then
-    return machine == 'arm64' or machine == 'aarch64'
-  end
-
-  if s == 'x86' or s == 'x86_64' or s == 'amd64' then
-    return machine == 'x86_64'
-  end
-
-  return machine == s
-end
-
 local function tmpdir_get()
   return os.getenv('TMPDIR') and os.getenv('TMPDIR') or os.getenv('TEMP')
 end
 
--- Is temp directory `dir` defined local to the project workspace?
+--- Is temp directory `dir` defined local to the project workspace?
+--- @param dir string?
+--- @return boolean
 local function tmpdir_is_local(dir)
-  return not not (dir and string.find(dir, 'Xtest'))
+  return not not (dir and dir:find('Xtest'))
 end
 
 --- Creates a new temporary file for use by tests.
@@ -422,14 +424,6 @@ module.tmpname = (function()
   end
 end)()
 
-function module.hasenv(name)
-  local env = os.getenv(name)
-  if env and env ~= '' then
-    return env
-  end
-  return nil
-end
-
 local function deps_prefix()
   local env = os.getenv('DEPS_PREFIX')
   return (env and env ~= '') and env or '.deps/usr'
@@ -443,6 +437,7 @@ function module.check_cores(app, force) -- luacheck: ignore
     return
   end
   app = app or 'build/bin/nvim' -- luacheck: ignore
+  --- @type string, string?, string[]
   local initial_path, re, exc_re
   local gdb_db_cmd =
     'gdb -n -batch -ex "thread apply all bt full" "$_NVIM_TEST_APP" -c "$_NVIM_TEST_CORE"'
@@ -455,13 +450,14 @@ function module.check_cores(app, force) -- luacheck: ignore
       and relpath(tmpdir_get()):gsub('^[ ./]+', ''):gsub('%/+$', ''):gsub('([^%w])', '%%%1')
     or nil
   )
-  local db_cmd
-  if module.hasenv('NVIM_TEST_CORE_GLOB_DIRECTORY') then
-    initial_path = os.getenv('NVIM_TEST_CORE_GLOB_DIRECTORY')
+  local db_cmd --- @type string
+  local test_glob_dir = os.getenv('NVIM_TEST_CORE_GLOB_DIRECTORY')
+  if test_glob_dir and test_glob_dir ~= '' then
+    initial_path = test_glob_dir
     re = os.getenv('NVIM_TEST_CORE_GLOB_RE')
     exc_re = { os.getenv('NVIM_TEST_CORE_EXC_RE'), local_tmpdir }
     db_cmd = os.getenv('NVIM_TEST_CORE_DB_CMD') or gdb_db_cmd
-    random_skip = os.getenv('NVIM_TEST_CORE_RANDOM_SKIP')
+    random_skip = os.getenv('NVIM_TEST_CORE_RANDOM_SKIP') ~= ''
   elseif module.is_os('mac') then
     initial_path = '/cores'
     re = nil
@@ -519,21 +515,28 @@ function module.repeated_read_cmd(...)
   return nil
 end
 
+--- @generic T
+--- @param orig T
+--- @return T
 function module.shallowcopy(orig)
   if type(orig) ~= 'table' then
     return orig
   end
-  local copy = {}
+  --- @cast orig table<any,any>
+  local copy = {} --- @type table<any,any>
   for orig_key, orig_value in pairs(orig) do
     copy[orig_key] = orig_value
   end
   return copy
 end
 
+--- @param d1 table<any,any>
+--- @param d2 table<any,any>
+--- @return table<any,any>
 function module.mergedicts_copy(d1, d2)
   local ret = module.shallowcopy(d1)
   for k, v in pairs(d2) do
-    if d2[k] == module.REMOVE_THIS then
+    if d2[k] == vim.NIL then
       ret[k] = nil
     elseif type(d1[k]) == 'table' and type(v) == 'table' then
       ret[k] = module.mergedicts_copy(d1[k], v)
@@ -544,16 +547,18 @@ function module.mergedicts_copy(d1, d2)
   return ret
 end
 
--- dictdiff: find a diff so that mergedicts_copy(d1, diff) is equal to d2
---
--- Note: does not do copies of d2 values used.
+--- dictdiff: find a diff so that mergedicts_copy(d1, diff) is equal to d2
+---
+--- Note: does not do copies of d2 values used.
+--- @param d1 table<any,any>
+--- @param d2 table<any,any>
 function module.dictdiff(d1, d2)
-  local ret = {}
+  local ret = {} --- @type table<any,any>
   local hasdiff = false
   for k, v in pairs(d1) do
     if d2[k] == nil then
       hasdiff = true
-      ret[k] = module.REMOVE_THIS
+      ret[k] = vim.NIL
     elseif type(v) == type(d2[k]) then
       if type(v) == 'table' then
         local subdiff = module.dictdiff(v, d2[k])
@@ -584,17 +589,11 @@ function module.dictdiff(d1, d2)
   end
 end
 
-function module.updated(d, d2)
-  for k, v in pairs(d2) do
-    d[k] = v
-  end
-  return d
-end
-
 -- Concat list-like tables.
 function module.concat_tables(...)
-  local ret = {}
+  local ret = {} --- @type table<any,any>
   for i = 1, select('#', ...) do
+    --- @type table<any,any>
     local tbl = select(i, ...)
     if tbl then
       for _, v in ipairs(tbl) do
@@ -633,192 +632,13 @@ function module.dedent(str, leave_indent)
   return str
 end
 
-local function format_float(v)
-  -- On windows exponent appears to have three digits and not two
-  local ret = ('%.6e'):format(v)
-  local l, f, es, e = ret:match('^(%-?%d)%.(%d+)e([+%-])0*(%d%d+)$')
-  return l .. '.' .. f .. 'e' .. es .. e
-end
-
-local SUBTBL = {
-  '\\000',
-  '\\001',
-  '\\002',
-  '\\003',
-  '\\004',
-  '\\005',
-  '\\006',
-  '\\007',
-  '\\008',
-  '\\t',
-  '\\n',
-  '\\011',
-  '\\012',
-  '\\r',
-  '\\014',
-  '\\015',
-  '\\016',
-  '\\017',
-  '\\018',
-  '\\019',
-  '\\020',
-  '\\021',
-  '\\022',
-  '\\023',
-  '\\024',
-  '\\025',
-  '\\026',
-  '\\027',
-  '\\028',
-  '\\029',
-  '\\030',
-  '\\031',
-}
-
--- Formats Lua value `v`.
---
--- TODO(justinmk): redundant with vim.inspect() ?
---
--- "Nice table formatting similar to screen:snapshot_util()".
--- Commit: 520c0b91a528
-function module.format_luav(v, indent, opts)
-  opts = opts or {}
-  local linesep = '\n'
-  local next_indent_arg = nil
-  local indent_shift = opts.indent_shift or '  '
-  local next_indent
-  local nl = '\n'
-  if indent == nil then
-    indent = ''
-    linesep = ''
-    next_indent = ''
-    nl = ' '
-  else
-    next_indent_arg = indent .. indent_shift
-    next_indent = indent .. indent_shift
-  end
-  local ret = ''
-  if type(v) == 'string' then
-    if opts.literal_strings then
-      ret = v
-    else
-      local quote = opts.dquote_strings and '"' or "'"
-      ret = quote
-        .. tostring(v)
-          :gsub(opts.dquote_strings and '["\\]' or "['\\]", '\\%0')
-          :gsub('[%z\1-\31]', function(match)
-            return SUBTBL[match:byte() + 1]
-          end)
-        .. quote
-    end
-  elseif type(v) == 'table' then
-    if v == module.REMOVE_THIS then
-      ret = 'REMOVE_THIS'
-    else
-      local processed_keys = {}
-      ret = '{' .. linesep
-      local non_empty = false
-      local format_luav = module.format_luav
-      for i, subv in ipairs(v) do
-        ret = ('%s%s%s,%s'):format(ret, next_indent, format_luav(subv, next_indent_arg, opts), nl)
-        processed_keys[i] = true
-        non_empty = true
-      end
-      for k, subv in pairs(v) do
-        if not processed_keys[k] then
-          if type(k) == 'string' and k:match('^[a-zA-Z_][a-zA-Z0-9_]*$') then
-            ret = ret .. next_indent .. k .. ' = '
-          else
-            ret = ('%s%s[%s] = '):format(ret, next_indent, format_luav(k, nil, opts))
-          end
-          ret = ret .. format_luav(subv, next_indent_arg, opts) .. ',' .. nl
-          non_empty = true
-        end
-      end
-      if nl == ' ' and non_empty then
-        ret = ret:sub(1, -3)
-      end
-      ret = ret .. indent .. '}'
-    end
-  elseif type(v) == 'number' then
-    if v % 1 == 0 then
-      ret = ('%d'):format(v)
-    else
-      ret = format_float(v)
-    end
-  elseif type(v) == 'nil' then
-    ret = 'nil'
-  elseif type(v) == 'boolean' then
-    ret = (v and 'true' or 'false')
-  else
-    print(type(v))
-    -- Not implemented yet
-    luaassert(false)
-  end
-  return ret
-end
-
--- Like Python repr(), "{!r}".format(s)
---
--- Commit: 520c0b91a528
-function module.format_string(fmt, ...)
-  local i = 0
-  local args = { ... }
-  local function getarg()
-    i = i + 1
-    return args[i]
-  end
-  local ret = fmt:gsub('%%[0-9*]*%.?[0-9*]*[cdEefgGiouXxqsr%%]', function(match)
-    local subfmt = match:gsub('%*', function()
-      return tostring(getarg())
-    end)
-    local arg = nil
-    if subfmt:sub(-1) ~= '%' then
-      arg = getarg()
-    end
-    if subfmt:sub(-1) == 'r' or subfmt:sub(-1) == 'q' then
-      -- %r is like built-in %q, but it is supposed to single-quote strings and
-      -- not double-quote them, and also work not only for strings.
-      -- Builtin %q is replaced here as it gives invalid and inconsistent with
-      -- luajit results for e.g. "\e" on lua: luajit transforms that into `\27`,
-      -- lua leaves as-is.
-      arg = module.format_luav(arg, nil, { dquote_strings = (subfmt:sub(-1) == 'q') })
-      subfmt = subfmt:sub(1, -2) .. 's'
-    end
-    if subfmt == '%e' then
-      return format_float(arg)
-    else
-      return subfmt:format(arg)
-    end
-  end)
-  return ret
-end
-
 function module.intchar2lua(ch)
   ch = tonumber(ch)
   return (20 <= ch and ch < 127) and ('%c'):format(ch) or ch
 end
 
-local fixtbl_metatable = {
-  __newindex = function()
-    luaassert(false)
-  end,
-}
-
-function module.fixtbl(tbl)
-  return setmetatable(tbl, fixtbl_metatable)
-end
-
-function module.fixtbl_rec(tbl)
-  local fixtbl_rec = module.fixtbl_rec
-  for _, v in pairs(tbl) do
-    if type(v) == 'table' then
-      fixtbl_rec(v)
-    end
-  end
-  return module.fixtbl(tbl)
-end
-
+--- @param str string
+--- @return string
 function module.hexdump(str)
   local len = string.len(str)
   local dump = ''
@@ -844,10 +664,10 @@ function module.hexdump(str)
   return dump .. hex .. string.rep('   ', 8 - len % 8) .. asc
 end
 
--- Reads text lines from `filename` into a table.
---
--- filename: path to file
--- start: start line (1-indexed), negative means "lines before end" (tail)
+--- Reads text lines from `filename` into a table.
+--- @param filename string path to file
+--- @param start? integer start line (1-indexed), negative means "lines before end" (tail)
+--- @return string[]?
 function module.read_file_list(filename, start)
   local lnum = (start ~= nil and type(start) == 'number') and start or 1
   local tail = (lnum < 0)
@@ -883,9 +703,9 @@ function module.read_file_list(filename, start)
   return lines
 end
 
--- Reads the entire contents of `filename` into a string.
---
--- filename: path to file
+--- Reads the entire contents of `filename` into a string.
+--- @param filename string
+--- @return string?
 function module.read_file(filename)
   local file = io.open(filename, 'r')
   if not file then
@@ -901,6 +721,7 @@ function module.write_file(name, text, no_dedent, append)
   local file = assert(io.open(name, (append and 'a' or 'w')))
   if type(text) == 'table' then
     -- Byte blob
+    --- @type string[]
     local bytes = text
     text = ''
     for _, char in ipairs(bytes) do
@@ -914,6 +735,8 @@ function module.write_file(name, text, no_dedent, append)
   file:close()
 end
 
+--- @param name? 'cirrus'|'github'
+--- @return boolean
 function module.is_ci(name)
   local any = (name == nil)
   luaassert(any or name == 'github' or name == 'cirrus')
@@ -946,12 +769,10 @@ function module.read_nvim_log(logfile, ci_rename)
 end
 
 --- @param path string
---- @return string
+--- @return boolean?
 function module.mkdir(path)
   -- 493 is 0755 in decimal
-  return uv.fs_mkdir(path, 493)
+  return (uv.fs_mkdir(path, 493))
 end
 
-module = vim.tbl_extend('error', module, Paths, require('test.deprecated'))
-
 return module
diff --git a/test/unit/helpers.lua b/test/unit/helpers.lua
index 47499d98fa..ab4a59cfdb 100644
--- a/test/unit/helpers.lua
+++ b/test/unit/helpers.lua
@@ -2,8 +2,8 @@ local ffi = require('ffi')
 local formatc = require('test.unit.formatc')
 local Set = require('test.unit.set')
 local Preprocess = require('test.unit.preprocess')
-local Paths = require('test.cmakeconfig.paths')
 local global_helpers = require('test.helpers')
+local paths = global_helpers.paths
 local assert = require('luassert')
 local say = require('say')
 
@@ -15,7 +15,7 @@ local eq = global_helpers.eq
 local trim = vim.trim
 
 -- add some standard header locations
-for _, p in ipairs(Paths.include_paths) do
+for _, p in ipairs(paths.include_paths) do
   Preprocess.add_to_include_path(p)
 end
 
@@ -728,7 +728,7 @@ local function check_child_err(rd)
         --- @type string
         err = err .. '\nNo end of trace occurred'
       end
-      local cc_err, cc_emsg = pcall(check_cores, Paths.test_luajit_prg, true)
+      local cc_err, cc_emsg = pcall(check_cores, paths.test_luajit_prg, true)
       if not cc_err then
         --- @type string
         err = err .. '\ncheck_cores failed: ' .. cc_emsg
@@ -749,7 +749,7 @@ local function itp_parent(rd, pid, allow_failure, location)
       io.stderr:write('Errorred out (' .. status .. '):\n' .. tostring(emsg) .. '\n')
       os.execute([[
         sh -c "source ci/common/test.sh
-        check_core_dumps --delete \"]] .. Paths.test_luajit_prg .. [[\""]])
+        check_core_dumps --delete \"]] .. paths.test_luajit_prg .. [[\""]])
     else
       error(tostring(emsg) .. '\nexit code: ' .. status)
     end
@@ -797,7 +797,7 @@ local function gen_itp(it)
 end
 
 local function cppimport(path)
-  return cimport(Paths.test_source_path .. '/test/includes/pre/' .. path)
+  return cimport(paths.test_source_path .. '/test/includes/pre/' .. path)
 end
 
 cimport(
diff --git a/test/unit/viml/expressions/parser_spec.lua b/test/unit/viml/expressions/parser_spec.lua
index ae12136a5c..c7d3f8532f 100644
--- a/test/unit/viml/expressions/parser_spec.lua
+++ b/test/unit/viml/expressions/parser_spec.lua
@@ -14,8 +14,8 @@ local ffi = helpers.ffi
 local neq = helpers.neq
 local eq = helpers.eq
 local mergedicts_copy = helpers.mergedicts_copy
-local format_string = helpers.format_string
-local format_luav = helpers.format_luav
+local format_string = require('test.format_string').format_string
+local format_luav = require('test.format_string').format_luav
 local intchar2lua = helpers.intchar2lua
 local dictdiff = helpers.dictdiff
 
diff --git a/test/unit/viml/expressions/parser_tests.lua b/test/unit/viml/expressions/parser_tests.lua
index a10e1098b5..aa2bf740de 100644
--- a/test/unit/viml/expressions/parser_tests.lua
+++ b/test/unit/viml/expressions/parser_tests.lua
@@ -1,6 +1,4 @@
-local global_helpers = require('test.helpers')
-
-local REMOVE_THIS = global_helpers.REMOVE_THIS
+local REMOVE_THIS = vim.NIL
 
 return function(itp, _check_parsing, hl, fmtn)
   local function check_parsing(...)