test: add type annotations

5 files changed, 268 insertions, 91 deletions

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/functional/helpers.lua b/test/functional/helpers.lua
index e1fbfe6ff3..eddf336b6f 100644
--- a/test/functional/helpers.lua
+++ b/test/functional/helpers.lua
@@ -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
@@ -311,14 +337,18 @@ function module.expect_exit(fn_or_timeout, ...)
   end
 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)
@@ -330,22 +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
@@ -357,26 +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) }
@@ -421,7 +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()
@@ -457,16 +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')
@@ -475,16 +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')
@@ -523,6 +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
@@ -532,8 +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
@@ -587,6 +644,9 @@ end
 
 function module.create_callindex(func)
   return setmetatable({}, {
+    --- @param tbl table<any,function>
+    --- @param arg1 string
+    --- @return function
     __index = function(tbl, arg1)
       local ret = function(...)
         return func(arg1, ...)
@@ -597,12 +657,17 @@ function module.create_callindex(func)
   })
 end
 
+--- @param method string
+--- @param ... any
 function module.nvim_async(method, ...)
-  session:notify(method, ...)
+  assert(session):notify(method, ...)
 end
 
--- Executes a Vimscript function via RPC.
--- Fails on Vimscript error, but does not update v:errmsg.
+--- 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
@@ -637,6 +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
 
@@ -673,6 +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'
@@ -712,6 +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
@@ -779,14 +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
@@ -809,6 +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
@@ -855,19 +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
@@ -876,14 +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
@@ -893,18 +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
@@ -918,7 +1006,9 @@ function module.add_builddir_to_rtp()
   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(
     (
@@ -928,7 +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/helpers.lua b/test/helpers.lua
index fa09942bc9..f0cb395c89 100644
--- a/test/helpers.lua
+++ b/test/helpers.lua
@@ -63,8 +63,12 @@ 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)
@@ -72,6 +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
@@ -121,6 +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
@@ -170,10 +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, ...)
@@ -221,6 +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, ...)
@@ -230,19 +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
@@ -252,9 +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
@@ -301,7 +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]
@@ -313,6 +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
@@ -320,6 +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
@@ -364,9 +392,11 @@ 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.
@@ -410,6 +440,7 @@ 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"'
@@ -422,14 +453,14 @@ function module.check_cores(app, force) -- luacheck: ignore
       and relpath(tmpdir_get()):gsub('^[ ./]+', ''):gsub('%/+$', ''):gsub('([^%w])', '%%%1')
     or nil
   )
-  local db_cmd
+  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
@@ -487,17 +518,24 @@ 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
@@ -512,11 +550,13 @@ 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
@@ -554,8 +594,9 @@ 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
@@ -787,10 +828,10 @@ 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)
@@ -826,9 +867,9 @@ 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
@@ -844,6 +885,7 @@ 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
@@ -857,6 +899,8 @@ 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')