Merge branch 'master' into option-fixes

9 files changed, 389 insertions, 110 deletions

diff --git a/test/unit/eval/decode_spec.lua b/test/unit/eval/decode_spec.lua
index 0b2a423cd6..0c444b33f2 100644
--- a/test/unit/eval/decode_spec.lua
+++ b/test/unit/eval/decode_spec.lua
@@ -2,7 +2,6 @@ local helpers = require('test.unit.helpers')(after_each)
 local itp = helpers.gen_itp(it)
 
 local cimport = helpers.cimport
-local to_cstr = helpers.to_cstr
 local eq = helpers.eq
 local neq = helpers.neq
 local ffi = helpers.ffi
@@ -72,7 +71,7 @@ describe('json_decode_string()', function()
   end
 
   itp('does not overflow in error messages', function()
-    local saved_p_enc = decode.p_enc
+    collectgarbage('restart')
     check_failure(']test', 1, 'E474: No container to close: ]')
     check_failure('[}test', 2, 'E474: Closing list with curly bracket: }')
     check_failure('{]test', 2,
@@ -105,10 +104,6 @@ describe('json_decode_string()', function()
     check_failure('"\194"test', 3, 'E474: Only UTF-8 strings allowed: \194"')
     check_failure('"\252\144\128\128\128\128"test', 8, 'E474: Only UTF-8 code points up to U+10FFFF are allowed to appear unescaped: \252\144\128\128\128\128"')
     check_failure('"test', 1, 'E474: Expected string end: "')
-    decode.p_enc = to_cstr('latin1')
-    check_failure('"\\uABCD"test', 8,
-                  'E474: Failed to convert string "ꯍ" from UTF-8')
-    decode.p_enc = saved_p_enc
     check_failure('-test', 1, 'E474: Missing number after minus sign: -')
     check_failure('-1.test', 3, 'E474: Missing number after decimal dot: -1.')
     check_failure('-1.0etest', 5, 'E474: Missing exponent: -1.0e')
diff --git a/test/unit/eval/helpers.lua b/test/unit/eval/helpers.lua
index fa76113756..5bc482216e 100644
--- a/test/unit/eval/helpers.lua
+++ b/test/unit/eval/helpers.lua
@@ -468,7 +468,7 @@ local function tbl2callback(tbl)
                                    data={funcref=eval.xstrdup(tbl.fref)}}})
   elseif tbl.type == 'pt' then
     local pt = ffi.gc(ffi.cast('partial_T*',
-        eval.xcalloc(1, ffi.sizeof('partial_T'))), eval.partial_unref)
+        eval.xcalloc(1, ffi.sizeof('partial_T'))), nil)
     ret = ffi.new('Callback[1]', {{type=eval.kCallbackPartial,
                                    data={partial=populate_partial(pt, tbl.pt, {})}}})
   else
diff --git a/test/unit/eval/typval_spec.lua b/test/unit/eval/typval_spec.lua
index 258b5c4c1f..6308ae7367 100644
--- a/test/unit/eval/typval_spec.lua
+++ b/test/unit/eval/typval_spec.lua
@@ -47,6 +47,15 @@ local lib = cimport('./src/nvim/eval/typval.h', './src/nvim/memory.h',
                     './src/nvim/eval.h', './src/nvim/vim.h',
                     './src/nvim/globals.h')
 
+local function vimconv_alloc()
+  return ffi.gc(
+    ffi.cast('vimconv_T*', lib.xcalloc(1, ffi.sizeof('vimconv_T'))),
+    function(vc)
+      lib.convert_setup(vc, nil, nil)
+      lib.xfree(vc)
+    end)
+end
+
 local function list_watch_alloc(li)
   return ffi.cast('listwatch_T*', ffi.new('listwatch_T[1]', {{lw_item=li}}))
 end
@@ -237,24 +246,33 @@ describe('typval.c', function()
             list_watch(l, lis[4]),
             list_watch(l, lis[7]),
           }
+          alloc_log:check({
+            a.list(l),
+            a.li(lis[1]),
+            a.li(lis[2]),
+            a.li(lis[3]),
+            a.li(lis[4]),
+            a.li(lis[5]),
+            a.li(lis[6]),
+            a.li(lis[7]),
+          })
 
           lib.tv_list_item_remove(l, lis[4])
-          ffi.gc(lis[4], lib.tv_list_item_free)
+          alloc_log:check({a.freed(lis[4])})
           eq({lis[1], lis[5], lis[7]}, {lws[1].lw_item, lws[2].lw_item, lws[3].lw_item})
 
           lib.tv_list_item_remove(l, lis[2])
-          ffi.gc(lis[2], lib.tv_list_item_free)
+          alloc_log:check({a.freed(lis[2])})
           eq({lis[1], lis[5], lis[7]}, {lws[1].lw_item, lws[2].lw_item, lws[3].lw_item})
 
           lib.tv_list_item_remove(l, lis[7])
-          ffi.gc(lis[7], lib.tv_list_item_free)
+          alloc_log:check({a.freed(lis[7])})
           eq({lis[1], lis[5], nil}, {lws[1].lw_item, lws[2].lw_item, lws[3].lw_item == nil and nil})
 
           lib.tv_list_item_remove(l, lis[1])
-          ffi.gc(lis[1], lib.tv_list_item_free)
+          alloc_log:check({a.freed(lis[1])})
           eq({lis[3], lis[5], nil}, {lws[1].lw_item, lws[2].lw_item, lws[3].lw_item == nil and nil})
 
-          alloc_log:clear()
           lib.tv_list_watch_remove(l, lws[2])
           lib.tv_list_watch_remove(l, lws[3])
           lib.tv_list_watch_remove(l, lws[1])
@@ -460,6 +478,10 @@ describe('typval.c', function()
         eq(empty_list, typvalt2lua(l_tv))
         eq({true, true, true}, {lws[1].lw_item == nil, lws[2].lw_item == nil, lws[3].lw_item == nil})
 
+        lib.tv_list_watch_remove(l, lws[1])
+        lib.tv_list_watch_remove(l, lws[2])
+        lib.tv_list_watch_remove(l, lws[3])
+
         alloc_log:check({})
       end)
     end)
@@ -730,10 +752,8 @@ describe('typval.c', function()
         collectgarbage()
       end)
       itp('copies list correctly and converts items', function()
-        local vc = ffi.gc(ffi.new('vimconv_T[1]'), function(vc)
-          lib.convert_setup(vc, nil, nil)
-        end)
-        -- UTF-8 ↔ latin1 conversions need no iconv
+        local vc = vimconv_alloc()
+        -- UTF-8 ↔ latin1 conversions needs no iconv
         eq(OK, lib.convert_setup(vc, to_cstr('utf-8'), to_cstr('latin1')))
 
         local v = {{['«']='»'}, {'„'}, 1, '“', null_string, null_list, null_dict}
@@ -1087,12 +1107,16 @@ describe('typval.c', function()
       end)
     end)
     describe('join()', function()
-      local function list_join(l, sep, ret)
+      local function list_join(l, sep, join_ret)
         local ga = ga_alloc()
-        eq(ret or OK, lib.tv_list_join(ga, l, sep))
-        if ga.ga_data == nil then return ''
-        else return ffi.string(ga.ga_data)
+        eq(join_ret or OK, lib.tv_list_join(ga, l, sep))
+        local ret = ''
+        if ga.ga_data ~= nil then
+          ret = ffi.string(ga.ga_data)
         end
+        -- For some reason this is not working well in GC
+        lib.ga_clear(ffi.gc(ga, nil))
+        return ret
       end
       itp('works', function()
         local l
@@ -1508,7 +1532,7 @@ describe('typval.c', function()
           eq(s:sub(1, len), ffi.string(di.di_key))
           alloc_log:check({a.di(di, len)})
           if tv then
-            di.di_tv = tv
+            di.di_tv = ffi.gc(tv, nil)
           else
             di.di_tv.v_type = lib.VAR_UNKNOWN
           end
@@ -1539,7 +1563,7 @@ describe('typval.c', function()
           alloc_log:check({a.dict(d)})
           local di = ffi.gc(lib.tv_dict_item_alloc(''), nil)
           local tv = lua2typvalt('test')
-          di.di_tv = tv
+          di.di_tv = ffi.gc(tv, nil)
           alloc_log:check({a.di(di, ''), a.str(tv.vval.v_string, 'test')})
           eq(OK, lib.tv_dict_add(d, di))
           alloc_log:check({})
@@ -2131,9 +2155,7 @@ describe('typval.c', function()
         collectgarbage()
       end)
       itp('copies dict correctly and converts items', function()
-        local vc = ffi.gc(ffi.new('vimconv_T[1]'), function(vc)
-          lib.convert_setup(vc, nil, nil)
-        end)
+        local vc = vimconv_alloc()
         -- UTF-8 ↔ latin1 conversions need no iconv
         eq(OK, lib.convert_setup(vc, to_cstr('utf-8'), to_cstr('latin1')))
 
@@ -2428,6 +2450,10 @@ describe('typval.c', function()
                                'E741: Value is locked: Unknown'))
         eq(true, tv_check_lock(lib.VAR_FIXED, nil, 0,
                                'E742: Cannot change value of Unknown'))
+        eq(true, tv_check_lock(lib.VAR_LOCKED, nil, lib.kTVCstring,
+                               'E741: Value is locked: Unknown'))
+        eq(true, tv_check_lock(lib.VAR_FIXED, 'test', lib.kTVCstring,
+                               'E742: Cannot change value of test'))
       end)
     end)
     describe('equal()', function()
@@ -2659,7 +2685,8 @@ describe('typval.c', function()
             {lib.VAR_SPECIAL, {v_special=lib.kSpecialVarFalse}, nil, 0},
             {lib.VAR_UNKNOWN, nil, 'E685: Internal error: tv_get_number(UNKNOWN)', 0},
           }) do
-            local tv = typvalt(v[1], v[2])
+            -- Using to_cstr, cannot free with tv_clear
+            local tv = ffi.gc(typvalt(v[1], v[2]), nil)
             alloc_log:check({})
             local emsg = v[3]
             local ret = v[4]
@@ -2687,7 +2714,8 @@ describe('typval.c', function()
             {lib.VAR_SPECIAL, {v_special=lib.kSpecialVarFalse}, nil, 0},
             {lib.VAR_UNKNOWN, nil, 'E685: Internal error: tv_get_number(UNKNOWN)', 0},
           }) do
-            local tv = typvalt(v[1], v[2])
+            -- Using to_cstr, cannot free with tv_clear
+            local tv = ffi.gc(typvalt(v[1], v[2]), nil)
             alloc_log:check({})
             local emsg = v[3]
             local ret = {v[4], not not emsg}
@@ -2721,7 +2749,8 @@ describe('typval.c', function()
             {lib.VAR_UNKNOWN, nil, 'E685: Internal error: tv_get_number(UNKNOWN)', -1},
           }) do
             lib.curwin.w_cursor.lnum = 46
-            local tv = typvalt(v[1], v[2])
+            -- Using to_cstr, cannot free with tv_clear
+            local tv = ffi.gc(typvalt(v[1], v[2]), nil)
             alloc_log:check({})
             local emsg = v[3]
             local ret = v[4]
@@ -2749,7 +2778,8 @@ describe('typval.c', function()
             {lib.VAR_SPECIAL, {v_special=lib.kSpecialVarFalse}, 'E907: Using a special value as a Float', 0},
             {lib.VAR_UNKNOWN, nil, 'E685: Internal error: tv_get_float(UNKNOWN)', 0},
           }) do
-            local tv = typvalt(v[1], v[2])
+            -- Using to_cstr, cannot free with tv_clear
+            local tv = ffi.gc(typvalt(v[1], v[2]), nil)
             alloc_log:check({})
             local emsg = v[3]
             local ret = v[4]
@@ -2780,7 +2810,9 @@ describe('typval.c', function()
             {lib.VAR_SPECIAL, {v_special=lib.kSpecialVarFalse}, nil, 'false'},
             {lib.VAR_UNKNOWN, nil, 'E908: using an invalid value as a String', ''},
           }) do
-            local tv = typvalt(v[1], v[2])
+            -- Using to_cstr in place of Neovim allocated string, cannot
+            -- tv_clear() that.
+            local tv = ffi.gc(typvalt(v[1], v[2]), nil)
             alloc_log:check({})
             local emsg = v[3]
             local ret = v[4]
@@ -2821,7 +2853,8 @@ describe('typval.c', function()
             {lib.VAR_SPECIAL, {v_special=lib.kSpecialVarFalse}, nil, 'false'},
             {lib.VAR_UNKNOWN, nil, 'E908: using an invalid value as a String', nil},
           }) do
-            local tv = typvalt(v[1], v[2])
+            -- Using to_cstr, cannot free with tv_clear
+            local tv = ffi.gc(typvalt(v[1], v[2]), nil)
             alloc_log:check({})
             local emsg = v[3]
             local ret = v[4]
@@ -2861,7 +2894,8 @@ describe('typval.c', function()
             {lib.VAR_SPECIAL, {v_special=lib.kSpecialVarFalse}, nil, 'false'},
             {lib.VAR_UNKNOWN, nil, 'E908: using an invalid value as a String', ''},
           }) do
-            local tv = typvalt(v[1], v[2])
+            -- Using to_cstr, cannot free with tv_clear
+            local tv = ffi.gc(typvalt(v[1], v[2]), nil)
             alloc_log:check({})
             local emsg = v[3]
             local ret = v[4]
@@ -2902,7 +2936,8 @@ describe('typval.c', function()
             {lib.VAR_SPECIAL, {v_special=lib.kSpecialVarFalse}, nil, 'false'},
             {lib.VAR_UNKNOWN, nil, 'E908: using an invalid value as a String', nil},
           }) do
-            local tv = typvalt(v[1], v[2])
+            -- Using to_cstr, cannot free with tv_clear
+            local tv = ffi.gc(typvalt(v[1], v[2]), nil)
             alloc_log:check({})
             local emsg = v[3]
             local ret = v[4]
diff --git a/test/unit/fixtures/multiqueue.c b/test/unit/fixtures/multiqueue.c
index da63e55919..a8dca0a844 100644
--- a/test/unit/fixtures/multiqueue.c
+++ b/test/unit/fixtures/multiqueue.c
@@ -1,3 +1,6 @@
+// This is an open source non-commercial project. Dear PVS-Studio, please check
+// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+
 #include <string.h>
 #include <stdlib.h>
 #include "nvim/event/multiqueue.h"
diff --git a/test/unit/fixtures/rbuffer.c b/test/unit/fixtures/rbuffer.c
index d587d6b054..3f4062fa18 100644
--- a/test/unit/fixtures/rbuffer.c
+++ b/test/unit/fixtures/rbuffer.c
@@ -1,3 +1,6 @@
+// This is an open source non-commercial project. Dear PVS-Studio, please check
+// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+
 #include "nvim/rbuffer.h"
 #include "rbuffer.h"
 
diff --git a/test/unit/helpers.lua b/test/unit/helpers.lua
index 8aad3acd98..4b9f185156 100644
--- a/test/unit/helpers.lua
+++ b/test/unit/helpers.lua
@@ -11,6 +11,7 @@ local posix = nil
 local syscall = nil
 
 local check_cores = global_helpers.check_cores
+local dedent = global_helpers.dedent
 local neq = global_helpers.neq
 local map = global_helpers.map
 local eq = global_helpers.eq
@@ -511,6 +512,212 @@ if os.getenv('NVIM_TEST_PRINT_SYSCALLS') == '1' then
   end
 end
 
+local function just_fail(_)
+  return false
+end
+say:set('assertion.just_fail.positive', '%s')
+say:set('assertion.just_fail.negative', '%s')
+assert:register('assertion', 'just_fail', just_fail,
+                'assertion.just_fail.positive',
+                'assertion.just_fail.negative')
+
+local hook_fnamelen = 30
+local hook_sfnamelen = 30
+local hook_numlen = 5
+local hook_msglen = 1 + 1 + 1 + (1 + hook_fnamelen) + (1 + hook_sfnamelen) + (1 + hook_numlen) + 1
+
+local tracehelp = dedent([[
+  ┌ Trace type: _r_eturn from function , function _c_all, _l_ine executed,
+  │             _t_ail return, _C_ount (should not actually appear),
+  │             _s_aved from previous run for reference.
+  │┏ Function type: _L_ua function, _C_ function, _m_ain part of chunk,
+  │┃                function that did _t_ail call.
+  │┃┌ Function name type: _g_lobal, _l_ocal, _m_ethod, _f_ield, _u_pvalue,
+  │┃│                     space for unknown.
+  │┃│ ┏ Source file name             ┌ Function name                ┏ Line
+  │┃│ ┃ (trunc to 30 bytes, no .lua) │ (truncated to last 30 bytes) ┃ number
+  CWN SSSSSSSSSSSSSSSSSSSSSSSSSSSSSS:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFF:LLLLL\n
+]])
+
+local function child_sethook(wr)
+  local trace_level = os.getenv('NVIM_TEST_TRACE_LEVEL')
+  if not trace_level or trace_level == '' then
+    trace_level = 1
+  else
+    trace_level = tonumber(trace_level)
+  end
+  if trace_level <= 0 then
+    return
+  end
+  local trace_only_c = trace_level <= 1
+  local prev_info, prev_reason, prev_lnum
+  local function hook(reason, lnum, use_prev)
+    local info = nil
+    if use_prev then
+      info = prev_info
+    elseif reason ~= 'tail return' then  -- tail return
+      info = debug.getinfo(2, 'nSl')
+    end
+
+    if trace_only_c and (not info or info.what ~= 'C') and not use_prev then
+      if info.source:sub(-9) == '_spec.lua' then
+        prev_info = info
+        prev_reason = 'saved'
+        prev_lnum = lnum
+      end
+      return
+    end
+    if trace_only_c and not use_prev and prev_reason then
+      hook(prev_reason, prev_lnum, true)
+      prev_reason = nil
+    end
+
+    local whatchar = ' '
+    local namewhatchar = ' '
+    local funcname = ''
+    local source = ''
+    local msgchar = reason:sub(1, 1)
+
+    if reason == 'count' then
+      msgchar = 'C'
+    end
+
+    if info then
+      funcname = (info.name or ''):sub(1, hook_fnamelen)
+      whatchar = info.what:sub(1, 1)
+      namewhatchar = info.namewhat:sub(1, 1)
+      if namewhatchar == '' then
+        namewhatchar = ' '
+      end
+      source = info.source
+      if source:sub(1, 1) == '@' then
+        if source:sub(-4, -1) == '.lua' then
+          source = source:sub(1, -5)
+        end
+        source = source:sub(-hook_sfnamelen, -1)
+      end
+      lnum = lnum or info.currentline
+    end
+
+    -- assert(-1 <= lnum and lnum <= 99999)
+    local lnum_s
+    if lnum == -1 then
+      lnum_s = 'nknwn'
+    else
+      lnum_s = ('%u'):format(lnum)
+    end
+    local msg = (  -- lua does not support %*
+      ''
+      .. msgchar
+      .. whatchar
+      .. namewhatchar
+      .. ' '
+      .. source .. (' '):rep(hook_sfnamelen - #source)
+      .. ':'
+      .. funcname .. (' '):rep(hook_fnamelen - #funcname)
+      .. ':'
+      .. ('0'):rep(hook_numlen - #lnum_s) .. lnum_s
+      .. '\n'
+    )
+    -- eq(hook_msglen, #msg)
+    sc.write(wr, msg)
+  end
+  debug.sethook(hook, 'crl')
+end
+
+local trace_end_msg = ('E%s\n'):format((' '):rep(hook_msglen - 2))
+
+local function itp_child(wr, func)
+  init()
+  collectgarbage('stop')
+  child_sethook(wr)
+  local err, emsg = pcall(func)
+  collectgarbage('restart')
+  collectgarbage()
+  debug.sethook()
+  emsg = tostring(emsg)
+  sc.write(wr, trace_end_msg)
+  if not err then
+    if #emsg > 99999 then
+      emsg = emsg:sub(1, 99999)
+    end
+    sc.write(wr, ('-\n%05u\n%s'):format(#emsg, emsg))
+    deinit()
+    sc.close(wr)
+    sc.exit(1)
+  else
+    sc.write(wr, '+\n')
+    deinit()
+    sc.close(wr)
+    sc.exit(0)
+  end
+end
+
+local function check_child_err(rd)
+  local trace = {}
+  local did_traceline = false
+  while true do
+    local traceline = sc.read(rd, hook_msglen)
+    if #traceline ~= hook_msglen then
+      if #traceline == 0 then
+        break
+      else
+        trace[#trace + 1] = 'Partial read: <' .. trace .. '>\n'
+      end
+    end
+    if traceline == trace_end_msg then
+      did_traceline = true
+      break
+    end
+    trace[#trace + 1] = traceline
+  end
+  local res = sc.read(rd, 2)
+  if #res ~= 2 then
+    local error
+    if #trace == 0 then
+      error = '\nTest crashed, no trace available\n'
+    else
+      error = '\nTest crashed, trace:\n' .. tracehelp
+      for i = 1, #trace do
+        error = error .. trace[i]
+      end
+    end
+    if not did_traceline then
+      error = error .. '\nNo end of trace occurred'
+    end
+    local cc_err, cc_emsg = pcall(check_cores, Paths.test_luajit_prg, true)
+    if not cc_err then
+      error = error .. '\ncheck_cores failed: ' .. cc_emsg
+    end
+    assert.just_fail(error)
+  end
+  if res == '+\n' then
+    return
+  end
+  eq('-\n', res)
+  local len_s = sc.read(rd, 5)
+  local len = tonumber(len_s)
+  neq(0, len)
+  local err = sc.read(rd, len + 1)
+  assert.just_fail(err)
+end
+
+local function itp_parent(rd, pid, allow_failure)
+  local err, emsg = pcall(check_child_err, rd)
+  sc.wait(pid)
+  sc.close(rd)
+  if not err then
+    if allow_failure then
+      io.stderr:write('Errorred out:\n' .. tostring(emsg) .. '\n')
+      os.execute([[
+        sh -c "source ci/common/test.sh
+        check_core_dumps --delete \"]] .. Paths.test_luajit_prg .. [[\""]])
+    else
+      error(emsg)
+    end
+  end
+end
+
 local function gen_itp(it)
   child_calls_mod = {}
   child_calls_mod_once = {}
@@ -518,14 +725,6 @@ local function gen_itp(it)
   preprocess_cache_mod = map(function(v) return v end, preprocess_cache_init)
   previous_defines_mod = previous_defines_init
   cdefs_mod = cdefs_init:copy()
-  local function just_fail(_)
-    return false
-  end
-  say:set('assertion.just_fail.positive', '%s')
-  say:set('assertion.just_fail.negative', '%s')
-  assert:register('assertion', 'just_fail', just_fail,
-                  'assertion.just_fail.positive',
-                  'assertion.just_fail.negative')
   local function itp(name, func, allow_failure)
     if allow_failure and os.getenv('NVIM_TEST_RUN_FAILING_TESTS') ~= '1' then
       -- FIXME Fix tests with this true
@@ -535,50 +734,13 @@ local function gen_itp(it)
       local rd, wr = sc.pipe()
       child_pid = sc.fork()
       if child_pid == 0 then
-        init()
         sc.close(rd)
-        collectgarbage('stop')
-        local err, emsg = pcall(func)
-        collectgarbage('restart')
-        emsg = tostring(emsg)
-        if not err then
-          sc.write(wr, ('-\n%05u\n%s'):format(#emsg, emsg))
-          deinit()
-          sc.close(wr)
-          sc.exit(1)
-        else
-          sc.write(wr, '+\n')
-          deinit()
-          sc.close(wr)
-          sc.exit(0)
-        end
+        itp_child(wr, func)
       else
         sc.close(wr)
-        sc.wait(child_pid)
+        local saved_child_pid = child_pid
         child_pid = nil
-        local function check()
-          local res = sc.read(rd, 2)
-          eq(2, #res)
-          if res == '+\n' then
-            return
-          end
-          eq('-\n', res)
-          local len_s = sc.read(rd, 5)
-          local len = tonumber(len_s)
-          neq(0, len)
-          local err = sc.read(rd, len + 1)
-          assert.just_fail(err)
-        end
-        local err, emsg = pcall(check)
-        sc.close(rd)
-        if not err then
-          if allow_failure then
-            io.stderr:write('Errorred out:\n' .. tostring(emsg) .. '\n')
-            os.execute([[sh -c "source .ci/common/test.sh ; check_core_dumps --delete \"]] .. Paths.test_luajit_prg .. [[\""]])
-          else
-            error(emsg)
-          end
-        end
+        itp_parent(rd, saved_child_pid, allow_failure)
       end
     end)
   end
@@ -610,12 +772,8 @@ local module = {
   only_separate = only_separate,
   child_call_once = child_call_once,
   child_cleanup_once = child_cleanup_once,
+  sc = sc,
 }
-return function(after_each)
-  if after_each then
-    after_each(function()
-      check_cores(Paths.test_luajit_prg)
-    end)
-  end
+return function()
   return module
 end
diff --git a/test/unit/os/env_spec.lua b/test/unit/os/env_spec.lua
index 823b6d6a85..575787a25e 100644
--- a/test/unit/os/env_spec.lua
+++ b/test/unit/os/env_spec.lua
@@ -67,12 +67,37 @@ describe('env function', function()
     end)
   end)
 
+  describe('os_shell_is_cmdexe', function()
+    itp('returns true for expected names', function()
+      eq(true, cimp.os_shell_is_cmdexe(to_cstr('cmd.exe')))
+      eq(true, cimp.os_shell_is_cmdexe(to_cstr('cmd')))
+      eq(true, cimp.os_shell_is_cmdexe(to_cstr('CMD.EXE')))
+      eq(true, cimp.os_shell_is_cmdexe(to_cstr('CMD')))
+
+      os_setenv('COMSPEC', '/foo/bar/cmd.exe', 0)
+      eq(true, cimp.os_shell_is_cmdexe(to_cstr('$COMSPEC')))
+      os_setenv('COMSPEC', [[C:\system32\cmd.exe]], 0)
+      eq(true, cimp.os_shell_is_cmdexe(to_cstr('$COMSPEC')))
+    end)
+    itp('returns false for unexpected names', function()
+      eq(false, cimp.os_shell_is_cmdexe(to_cstr('')))
+      eq(false, cimp.os_shell_is_cmdexe(to_cstr('powershell')))
+      eq(false, cimp.os_shell_is_cmdexe(to_cstr(' cmd.exe ')))
+      eq(false, cimp.os_shell_is_cmdexe(to_cstr('cm')))
+      eq(false, cimp.os_shell_is_cmdexe(to_cstr('md')))
+      eq(false, cimp.os_shell_is_cmdexe(to_cstr('cmd.ex')))
+
+      os_setenv('COMSPEC', '/foo/bar/cmd', 0)
+      eq(false, cimp.os_shell_is_cmdexe(to_cstr('$COMSPEC')))
+    end)
+  end)
+
   describe('os_getenv', function()
     itp('reads an env variable', function()
       local name = 'NVIM_UNIT_TEST_GETENV_1N'
       local value = 'NVIM_UNIT_TEST_GETENV_1V'
       eq(NULL, os_getenv(name))
-      -- need to use os_setenv, because lua dosn't have a setenv function
+      -- Use os_setenv because Lua dosen't have setenv.
       os_setenv(name, value, 1)
       eq(value, os_getenv(name))
     end)
diff --git a/test/unit/os/fileio_spec.lua b/test/unit/os/fileio_spec.lua
index 7a738ce85c..e3c8e616ce 100644
--- a/test/unit/os/fileio_spec.lua
+++ b/test/unit/os/fileio_spec.lua
@@ -80,6 +80,10 @@ local function file_read(fp, size)
   return ret1, ret2
 end
 
+local function file_flush(fp)
+  return m.file_flush(fp)
+end
+
 local function file_fsync(fp)
   return m.file_fsync(fp)
 end
@@ -94,7 +98,7 @@ describe('file_open', function()
     eq(0, err)
     local attrs = lfs.attributes(filec)
     eq('rwx------', attrs.permissions)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can create a rw------- file with kFileCreate', function()
@@ -102,7 +106,7 @@ describe('file_open', function()
     eq(0, err)
     local attrs = lfs.attributes(filec)
     eq('rw-------', attrs.permissions)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can create a rwx------ file with kFileCreateOnly', function()
@@ -110,7 +114,7 @@ describe('file_open', function()
     eq(0, err)
     local attrs = lfs.attributes(filec)
     eq('rwx------', attrs.permissions)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can create a rw------- file with kFileCreateOnly', function()
@@ -118,7 +122,7 @@ describe('file_open', function()
     eq(0, err)
     local attrs = lfs.attributes(filec)
     eq('rw-------', attrs.permissions)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('fails to open an existing file with kFileCreateOnly', function()
@@ -137,35 +141,35 @@ describe('file_open', function()
     local err, fp = file_open(file1, m.kFileCreate, 384)
     eq(0, err)
     eq(true, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can open an existing file read-only with zero', function()
     local err, fp = file_open(file1, 0, 384)
     eq(0, err)
     eq(false, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can open an existing file read-only with kFileReadOnly', function()
     local err, fp = file_open(file1, m.kFileReadOnly, 384)
     eq(0, err)
     eq(false, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can open an existing file read-only with kFileNoSymlink', function()
     local err, fp = file_open(file1, m.kFileNoSymlink, 384)
     eq(0, err)
     eq(false, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can truncate an existing file with kFileTruncate', function()
     local err, fp = file_open(file1, m.kFileTruncate, 384)
     eq(0, err)
     eq(true, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
     local attrs = lfs.attributes(file1)
     eq(0, attrs.size)
   end)
@@ -174,7 +178,7 @@ describe('file_open', function()
     local err, fp = file_open(file1, m.kFileWriteOnly, 384)
     eq(0, err)
     eq(true, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
     local attrs = lfs.attributes(file1)
     eq(4096, attrs.size)
   end)
@@ -191,7 +195,7 @@ describe('file_open', function()
     local err, fp = file_open(linkf, m.kFileTruncate, 384)
     eq(0, err)
     eq(true, fp.wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
     local attrs = lfs.attributes(file1)
     eq(0, attrs.size)
   end)
@@ -217,7 +221,7 @@ describe('file_open_new', function()
     local err, fp = file_open_new(file1, 0, 384)
     eq(0, err)
     eq(false, fp.wr)
-    eq(0, m.file_free(fp))
+    eq(0, m.file_free(fp, false))
   end)
 
   itp('fails to open an existing file with kFileCreateOnly', function()
@@ -227,7 +231,29 @@ describe('file_open_new', function()
   end)
 end)
 
--- file_close is called above, so it is not tested directly
+describe('file_close', function()
+  itp('can flush writes to disk also with true argument', function()
+    local err, fp = file_open(filec, m.kFileCreateOnly, 384)
+    eq(0, err)
+    local wsize = file_write(fp, 'test')
+    eq(4, wsize)
+    eq(0, lfs.attributes(filec).size)
+    eq(0, m.file_close(fp, true))
+    eq(wsize, lfs.attributes(filec).size)
+  end)
+end)
+
+describe('file_free', function()
+  itp('can flush writes to disk also with true argument', function()
+    local err, fp = file_open_new(filec, m.kFileCreateOnly, 384)
+    eq(0, err)
+    local wsize = file_write(fp, 'test')
+    eq(4, wsize)
+    eq(0, lfs.attributes(filec).size)
+    eq(0, m.file_free(fp, true))
+    eq(wsize, lfs.attributes(filec).size)
+  end)
+end)
 
 describe('file_fsync', function()
   itp('can flush writes to disk', function()
@@ -240,7 +266,22 @@ describe('file_fsync', function()
     eq(0, lfs.attributes(filec).size)
     eq(0, file_fsync(fp))
     eq(wsize, lfs.attributes(filec).size)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
+  end)
+end)
+
+describe('file_flush', function()
+  itp('can flush writes to disk', function()
+    local err, fp = file_open(filec, m.kFileCreateOnly, 384)
+    eq(0, file_flush(fp))
+    eq(0, err)
+    eq(0, lfs.attributes(filec).size)
+    local wsize = file_write(fp, 'test')
+    eq(4, wsize)
+    eq(0, lfs.attributes(filec).size)
+    eq(0, file_flush(fp))
+    eq(wsize, lfs.attributes(filec).size)
+    eq(0, m.file_close(fp, false))
   end)
 end)
 
@@ -262,7 +303,7 @@ describe('file_read', function()
       eq({exp_err, exp_s}, {file_read(fp, size)})
       shift = shift + size
     end
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can read the whole file at once', function()
@@ -271,7 +312,7 @@ describe('file_read', function()
     eq(false, fp.wr)
     eq({#fcontents, fcontents}, {file_read(fp, #fcontents)})
     eq({0, ('\0'):rep(#fcontents)}, {file_read(fp, #fcontents)})
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can read more then 1024 bytes after reading a small chunk', function()
@@ -281,7 +322,7 @@ describe('file_read', function()
     eq({5, fcontents:sub(1, 5)}, {file_read(fp, 5)})
     eq({#fcontents - 5, fcontents:sub(6) .. (('\0'):rep(5))},
        {file_read(fp, #fcontents)})
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 
   itp('can read file by 768-byte-chunks', function()
@@ -301,7 +342,7 @@ describe('file_read', function()
       eq({exp_err, exp_s}, {file_read(fp, size)})
       shift = shift + size
     end
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 end)
 
@@ -312,7 +353,7 @@ describe('file_write', function()
     eq(true, fp.wr)
     local wr = file_write(fp, fcontents)
     eq(#fcontents, wr)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
     eq(wr, lfs.attributes(filec).size)
     eq(fcontents, io.open(filec):read('*a'))
   end)
@@ -329,7 +370,7 @@ describe('file_write', function()
       eq(wr, #s)
       shift = shift + size
     end
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
     eq(#fcontents, lfs.attributes(filec).size)
     eq(fcontents, io.open(filec):read('*a'))
   end)
@@ -346,7 +387,7 @@ describe('file_write', function()
       eq(wr, #s)
       shift = shift + size
     end
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
     eq(#fcontents, lfs.attributes(filec).size)
     eq(fcontents, io.open(filec):read('*a'))
   end)
@@ -361,6 +402,6 @@ describe('file_skip', function()
     local rd, s = file_read(fp, 3)
     eq(3, rd)
     eq(fcontents:sub(4, 6), s)
-    eq(0, m.file_close(fp))
+    eq(0, m.file_close(fp, false))
   end)
 end)
diff --git a/test/unit/testtest_spec.lua b/test/unit/testtest_spec.lua
new file mode 100644
index 0000000000..d2f3632b6f
--- /dev/null
+++ b/test/unit/testtest_spec.lua
@@ -0,0 +1,19 @@
+local helpers = require('test.unit.helpers')(after_each)
+local assert = require('luassert')
+
+local itp = helpers.gen_itp(it)
+
+local sc = helpers.sc
+
+-- All of the below tests must fail. Check how exactly they fail.
+if os.getenv('NVIM_TEST_RUN_TESTTEST') ~= '1' then
+  return
+end
+describe('test code', function()
+  itp('does not hang when working with lengthy errors', function()
+    assert.just_fail(('x'):rep(65536))
+  end)
+  itp('shows trace after exiting abnormally', function()
+    sc.exit(0)
+  end)
+end)