Merge remote-tracking branch 'upstream/master' into mix_20240309

11 files changed, 221 insertions, 120 deletions

diff --git a/test/functional/options/autochdir_spec.lua b/test/functional/options/autochdir_spec.lua
index 11f71912a9..c490ab67a9 100644
--- a/test/functional/options/autochdir_spec.lua
+++ b/test/functional/options/autochdir_spec.lua
@@ -1,9 +1,11 @@
-local helpers = require('test.functional.helpers')(after_each)
-local clear = helpers.clear
-local eq = helpers.eq
-local fn = helpers.fn
-local command = helpers.command
-local mkdir = helpers.mkdir
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
+
+local clear = n.clear
+local eq = t.eq
+local fn = n.fn
+local command = n.command
+local mkdir = t.mkdir
 
 describe("'autochdir'", function()
   it('given on the shell gets processed properly', function()
@@ -16,7 +18,7 @@ describe("'autochdir'", function()
 
     -- With 'autochdir' on, we should get the directory of tty-test.c.
     clear('--cmd', 'set autochdir', targetdir .. '/tty-test.c')
-    eq(helpers.is_os('win') and expected:gsub('/', '\\') or expected, fn.getcwd())
+    eq(t.is_os('win') and expected:gsub('/', '\\') or expected, fn.getcwd())
   end)
 
   it('is not overwritten by getwinvar() call #17609', function()
@@ -38,7 +40,7 @@ describe("'autochdir'", function()
     eq(dir_a, fn.getcwd())
     fn.getwinvar(2, 'foo')
     eq(dir_a, fn.getcwd())
-    helpers.rmdir(dir_a)
-    helpers.rmdir(dir_b)
+    n.rmdir(dir_a)
+    n.rmdir(dir_b)
   end)
 end)
diff --git a/test/functional/options/chars_spec.lua b/test/functional/options/chars_spec.lua
index e9c20b5da9..8e63e07e09 100644
--- a/test/functional/options/chars_spec.lua
+++ b/test/functional/options/chars_spec.lua
@@ -1,12 +1,14 @@
-local helpers = require('test.functional.helpers')(after_each)
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear, command = helpers.clear, helpers.command
-local pcall_err = helpers.pcall_err
-local eval = helpers.eval
-local eq = helpers.eq
-local insert = helpers.insert
-local feed = helpers.feed
-local api = helpers.api
+
+local clear, command = n.clear, n.command
+local pcall_err = t.pcall_err
+local eval = n.eval
+local eq = t.eq
+local insert = n.insert
+local feed = n.feed
+local api = n.api
 
 describe("'fillchars'", function()
   local screen
@@ -22,7 +24,7 @@ describe("'fillchars'", function()
       eq('', eval('&fillchars'))
       screen:expect([[
         ^                         |
-        ~                        |*3
+        {1:~                        }|*3
                                  |
       ]])
     end)
@@ -30,13 +32,14 @@ describe("'fillchars'", function()
     it('supports whitespace', function()
       screen:expect([[
         ^                         |
-        ~                        |*3
+        {1:~                        }|*3
                                  |
       ]])
       command('set fillchars=eob:\\ ')
       screen:expect([[
         ^                         |
-                                 |*4
+        {1:                         }|*3
+                                 |
       ]])
     end)
 
@@ -44,7 +47,7 @@ describe("'fillchars'", function()
       command('set fillchars=eob:ñ')
       screen:expect([[
         ^                         |
-        ñ                        |*3
+        {1:ñ                        }|*3
                                  |
       ]])
     end)
@@ -53,7 +56,7 @@ describe("'fillchars'", function()
       command('set fillchars=eob:å̲')
       screen:expect([[
         ^                         |
-        å̲                        |*3
+        {1:å̲                        }|*3
                                  |
       ]])
     end)
@@ -112,8 +115,8 @@ describe("'fillchars'", function()
     command('vsplit')
     command('set fillchars=fold:x')
     screen:expect([[
-      ^+--  2 lines: fooxxxxxxxx│+--  2 lines: fooxxxxxxx|
-      ~                        │~                       |*3
+      {13:^+--  2 lines: fooxxxxxxxx}│{13:+--  2 lines: fooxxxxxxx}|
+      {1:~                        }│{1:~                       }|*3
                                                         |
     ]])
   end)
@@ -126,8 +129,8 @@ describe("'fillchars'", function()
     command('vsplit')
     command('setl fillchars=fold:x')
     screen:expect([[
-      ^+--  2 lines: fooxxxxxxxx│+--  2 lines: foo·······|
-      ~                        │~                       |*3
+      {13:^+--  2 lines: fooxxxxxxxx}│{13:+--  2 lines: foo·······}|
+      {1:~                        }│{1:~                       }|*3
                                                         |
     ]])
   end)
@@ -141,8 +144,8 @@ describe("'fillchars'", function()
     command('vsplit')
     command('set fillchars&')
     screen:expect([[
-      ^+--  2 lines: foo········│+--  2 lines: fooxxxxxxx|
-      ~                        │~                       |*3
+      {13:^+--  2 lines: foo········}│{13:+--  2 lines: fooxxxxxxx}|
+      {1:~                        }│{1:~                       }|*3
                                                         |
     ]])
   end)
@@ -163,8 +166,8 @@ describe("'listchars'", function()
     command('vsplit')
     command('set listchars=tab:<->')
     screen:expect([[
-      <------><------>^<------> │<------><------><------>|
-      ~                        │~                       |*3
+      {1:<------><------>^<------>} │{1:<------><------><------>}|
+      {1:~                        }│{1:~                       }|*3
                                                         |
     ]])
   end)
@@ -176,8 +179,8 @@ describe("'listchars'", function()
     command('vsplit')
     command('setl listchars<')
     screen:expect([[
-      >       >       ^>        │<------><------><------>|
-      ~                        │~                       |*3
+      {1:>       >       ^>       } │{1:<------><------><------>}|
+      {1:~                        }│{1:~                       }|*3
                                                         |
     ]])
   end)
@@ -189,8 +192,8 @@ describe("'listchars'", function()
     command('vsplit')
     command('set listchars=tab:>-,eol:$')
     screen:expect([[
-      >------->-------^>-------$│<------><------><------>|
-      ~                        │~                       |*3
+      {1:>------->-------^>-------$}│{1:<------><------><------>}|
+      {1:~                        }│{1:~                       }|*3
                                                         |
     ]])
   end)
diff --git a/test/functional/options/cursorbind_spec.lua b/test/functional/options/cursorbind_spec.lua
index cafdc83de2..19551b928f 100644
--- a/test/functional/options/cursorbind_spec.lua
+++ b/test/functional/options/cursorbind_spec.lua
@@ -1,9 +1,10 @@
-local helpers = require('test.functional.helpers')(after_each)
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear = helpers.clear
-local command = helpers.command
-local exec = helpers.exec
-local feed = helpers.feed
+
+local clear = n.clear
+local command = n.command
+local exec = n.exec
+local feed = n.feed
 
 before_each(clear)
 
diff --git a/test/functional/options/defaults_spec.lua b/test/functional/options/defaults_spec.lua
index d27fa375ee..f61139d92d 100644
--- a/test/functional/options/defaults_spec.lua
+++ b/test/functional/options/defaults_spec.lua
@@ -1,26 +1,27 @@
-local helpers = require('test.functional.helpers')(after_each)
-
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
 
-local assert_alive = helpers.assert_alive
-local assert_log = helpers.assert_log
-local api = helpers.api
-local command = helpers.command
-local clear = helpers.clear
-local exc_exec = helpers.exc_exec
-local exec_lua = helpers.exec_lua
-local eval = helpers.eval
-local eq = helpers.eq
-local ok = helpers.ok
-local fn = helpers.fn
-local insert = helpers.insert
-local neq = helpers.neq
-local mkdir = helpers.mkdir
-local rmdir = helpers.rmdir
-local alter_slashes = helpers.alter_slashes
+local assert_alive = n.assert_alive
+local assert_log = t.assert_log
+local api = n.api
+local command = n.command
+local clear = n.clear
+local exc_exec = n.exc_exec
+local exec_lua = n.exec_lua
+local eval = n.eval
+local eq = t.eq
+local ok = t.ok
+local fn = n.fn
+local insert = n.insert
+local neq = t.neq
+local mkdir = t.mkdir
+local rmdir = n.rmdir
+local alter_slashes = n.alter_slashes
 local tbl_contains = vim.tbl_contains
-local expect_exit = helpers.expect_exit
-local is_os = helpers.is_os
+local expect_exit = n.expect_exit
+local check_close = n.check_close
+local is_os = t.is_os
 
 local testlog = 'Xtest-defaults-log'
 
@@ -32,7 +33,7 @@ describe('startup defaults', function()
       command('filetype')
       screen:expect([[
         ^                                                  |
-        ~                                                 |*2
+        {1:~                                                 }|*2
         ]] .. expected)
     end
 
@@ -132,9 +133,9 @@ describe('startup defaults', function()
       command('vsp')
       screen:expect([[
         1                        │1                       |
-        ^+--  2 lines: 2··········│+--  2 lines: 2·········|
+        {13:^+--  2 lines: 2··········}│{13:+--  2 lines: 2·········}|
         4                        │4                       |
-        ~                        │~                       |
+        {1:~                        }│{1:~                       }|
                                                           |
       ]])
 
@@ -142,9 +143,9 @@ describe('startup defaults', function()
       command('set ambiwidth=double')
       screen:expect([[
         1                        |1                       |
-        ^+--  2 lines: 2----------|+--  2 lines: 2---------|
+        {13:^+--  2 lines: 2----------}|{13:+--  2 lines: 2---------}|
         4                        |4                       |
-        ~                        |~                       |
+        {1:~                        }|{1:~                       }|
                                                           |
       ]])
 
@@ -152,9 +153,9 @@ describe('startup defaults', function()
       fn.setcellwidths({ { 0x2502, 0x2502, 1 } })
       screen:expect([[
         1                        │1                       |
-        ^+--  2 lines: 2----------│+--  2 lines: 2---------|
+        {13:^+--  2 lines: 2----------}│{13:+--  2 lines: 2---------}|
         4                        │4                       |
-        ~                        │~                       |
+        {1:~                        }│{1:~                       }|
                                                           |
       ]])
 
@@ -162,9 +163,9 @@ describe('startup defaults', function()
       fn.setcellwidths({ { 0x2502, 0x2502, 2 } })
       screen:expect([[
         1                        |1                       |
-        ^+--  2 lines: 2----------|+--  2 lines: 2---------|
+        {13:^+--  2 lines: 2----------}|{13:+--  2 lines: 2---------}|
         4                        |4                       |
-        ~                        |~                       |
+        {1:~                        }|{1:~                       }|
                                                           |
       ]])
 
@@ -172,9 +173,9 @@ describe('startup defaults', function()
       command('set ambiwidth=single')
       screen:expect([[
         1                        |1                       |
-        ^+--  2 lines: 2··········|+--  2 lines: 2·········|
+        {13:^+--  2 lines: 2··········}|{13:+--  2 lines: 2·········}|
         4                        |4                       |
-        ~                        |~                       |
+        {1:~                        }|{1:~                       }|
                                                           |
       ]])
     end)
@@ -274,6 +275,7 @@ describe('XDG defaults', function()
   -- Do not put before_each() here for the same reasons.
 
   after_each(function()
+    check_close()
     os.remove(testlog)
   end)
 
@@ -378,7 +380,7 @@ describe('XDG defaults', function()
             .. root_path
             .. ('/b'):rep(2048)
             .. '/nvim'
-            .. (',' .. root_path .. '/c/nvim'):rep(512)
+            .. (',' .. root_path .. '/c/nvim')
             .. ','
             .. root_path
             .. ('/X'):rep(4096)
@@ -393,12 +395,12 @@ describe('XDG defaults', function()
             .. root_path
             .. ('/B'):rep(2048)
             .. '/nvim/site'
-            .. (',' .. root_path .. '/C/nvim/site'):rep(512)
+            .. (',' .. root_path .. '/C/nvim/site')
             .. ','
             .. vimruntime
             .. ','
             .. libdir
-            .. (',' .. root_path .. '/C/nvim/site/after'):rep(512)
+            .. (',' .. root_path .. '/C/nvim/site/after')
             .. ','
             .. root_path
             .. ('/B'):rep(2048)
@@ -413,7 +415,7 @@ describe('XDG defaults', function()
             .. '/'
             .. data_dir
             .. '/site/after'
-            .. (',' .. root_path .. '/c/nvim/after'):rep(512)
+            .. (',' .. root_path .. '/c/nvim/after')
             .. ','
             .. root_path
             .. ('/b'):rep(2048)
@@ -449,7 +451,7 @@ describe('XDG defaults', function()
             .. root_path
             .. ('/b'):rep(2048)
             .. '/nvim'
-            .. (',' .. root_path .. '/c/nvim'):rep(512)
+            .. (',' .. root_path .. '/c/nvim')
             .. ','
             .. root_path
             .. ('/X'):rep(4096)
@@ -464,12 +466,12 @@ describe('XDG defaults', function()
             .. root_path
             .. ('/B'):rep(2048)
             .. '/nvim/site'
-            .. (',' .. root_path .. '/C/nvim/site'):rep(512)
+            .. (',' .. root_path .. '/C/nvim/site')
             .. ','
             .. vimruntime
             .. ','
             .. libdir
-            .. (',' .. root_path .. '/C/nvim/site/after'):rep(512)
+            .. (',' .. root_path .. '/C/nvim/site/after')
             .. ','
             .. root_path
             .. ('/B'):rep(2048)
@@ -484,7 +486,7 @@ describe('XDG defaults', function()
             .. '/'
             .. data_dir
             .. '/site/after'
-            .. (',' .. root_path .. '/c/nvim/after'):rep(512)
+            .. (',' .. root_path .. '/c/nvim/after')
             .. ','
             .. root_path
             .. ('/b'):rep(2048)
@@ -865,6 +867,11 @@ describe('XDG defaults', function()
 end)
 
 describe('stdpath()', function()
+  after_each(function()
+    check_close()
+    os.remove(testlog)
+  end)
+
   -- Windows appends 'nvim-data' instead of just 'nvim' to prevent collisions
   -- due to XDG_CONFIG_HOME, XDG_DATA_HOME and XDG_STATE_HOME being the same.
   local function maybe_data(name)
@@ -890,7 +897,7 @@ describe('stdpath()', function()
 
   it('reacts to $NVIM_APPNAME', function()
     local appname = 'NVIM_APPNAME_TEST' .. ('_'):rep(106)
-    clear({ env = { NVIM_APPNAME = appname } })
+    clear({ env = { NVIM_APPNAME = appname, NVIM_LOG_FILE = testlog } })
     eq(appname, fn.fnamemodify(fn.stdpath('config'), ':t'))
     eq(appname, fn.fnamemodify(fn.stdpath('cache'), ':t'))
     eq(maybe_data(appname), fn.fnamemodify(fn.stdpath('log'), ':t'))
@@ -928,6 +935,9 @@ describe('stdpath()', function()
     -- Valid appnames:
     test_appname('a/b', 0)
     test_appname('a/b\\c', 0)
+    if not is_os('win') then
+      assert_log('Failed to start server: no such file or directory:', testlog)
+    end
   end)
 
   describe('returns a String', function()
@@ -1220,6 +1230,8 @@ describe('stdpath()', function()
   end)
 
   describe('errors', function()
+    before_each(clear)
+
     it('on unknown strings', function()
       eq('Vim(call):E6100: "capybara" is not a valid stdpath', exc_exec('call stdpath("capybara")'))
       eq('Vim(call):E6100: "" is not a valid stdpath', exc_exec('call stdpath("")'))
@@ -1235,7 +1247,8 @@ end)
 
 describe('autocommands', function()
   it('closes terminal with default shell on success', function()
-    api.nvim_set_option_value('shell', helpers.testprg('shell-test'), {})
+    clear()
+    api.nvim_set_option_value('shell', n.testprg('shell-test'), {})
     command('set shellcmdflag=EXIT shellredir= shellpipe= shellquote= shellxquote=')
 
     -- Should not block other events
@@ -1243,11 +1256,11 @@ describe('autocommands', function()
     command('au BufEnter * let g:n = g:n + 1')
 
     command('terminal')
-    eq(eval('get(g:, "n", 0)'), 1)
+    eq(1, eval('get(g:, "n", 0)'))
 
-    helpers.retry(nil, 1000, function()
-      neq(api.nvim_get_option_value('buftype', { buf = 0 }), 'terminal')
-      eq(eval('get(g:, "n", 0)'), 2)
+    t.retry(nil, 1000, function()
+      neq('terminal', api.nvim_get_option_value('buftype', { buf = 0 }))
+      eq(2, eval('get(g:, "n", 0)'))
     end)
   end)
 end)
diff --git a/test/functional/options/keymap_spec.lua b/test/functional/options/keymap_spec.lua
index 7be58888bc..f76525699f 100644
--- a/test/functional/options/keymap_spec.lua
+++ b/test/functional/options/keymap_spec.lua
@@ -1,8 +1,10 @@
-local helpers = require('test.functional.helpers')(after_each)
-local clear, feed, eq = helpers.clear, helpers.feed, helpers.eq
-local expect, command, eval = helpers.expect, helpers.command, helpers.eval
-local insert, call = helpers.insert, helpers.call
-local exec_capture, dedent = helpers.exec_capture, helpers.dedent
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
+
+local clear, feed, eq = n.clear, n.feed, t.eq
+local expect, command, eval = n.expect, n.command, n.eval
+local insert, call = n.insert, n.call
+local exec_capture, dedent = n.exec_capture, t.dedent
 
 -- First test it's implemented using the :lmap and :lnoremap commands, then
 -- check those mappings behave as expected.
diff --git a/test/functional/options/modified_spec.lua b/test/functional/options/modified_spec.lua
new file mode 100644
index 0000000000..956deb70ff
--- /dev/null
+++ b/test/functional/options/modified_spec.lua
@@ -0,0 +1,20 @@
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
+
+local clear = n.clear
+local eq = t.eq
+local api = n.api
+
+describe("'modified'", function()
+  before_each(function()
+    clear()
+  end)
+
+  it("can be unset after changing 'fileformat'", function()
+    for _, ff in ipairs({ 'unix', 'dos', 'mac' }) do
+      api.nvim_set_option_value('fileformat', ff, {})
+      api.nvim_set_option_value('modified', false, {})
+      eq(false, api.nvim_get_option_value('modified', {}), 'fileformat=' .. ff)
+    end
+  end)
+end)
diff --git a/test/functional/options/mousescroll_spec.lua b/test/functional/options/mousescroll_spec.lua
index 96af8987b8..2ccf934fd4 100644
--- a/test/functional/options/mousescroll_spec.lua
+++ b/test/functional/options/mousescroll_spec.lua
@@ -1,21 +1,23 @@
-local helpers = require('test.functional.helpers')(after_each)
-local command = helpers.command
-local clear = helpers.clear
-local eval = helpers.eval
-local eq = helpers.eq
-local exc_exec = helpers.exc_exec
-local feed = helpers.feed
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
+
+local command = n.command
+local clear = n.clear
+local eval = n.eval
+local eq = t.eq
+local exc_exec = n.exc_exec
+local feed = n.feed
 
 local scroll = function(direction)
-  return helpers.request('nvim_input_mouse', 'wheel', direction, '', 0, 2, 2)
+  return n.request('nvim_input_mouse', 'wheel', direction, '', 0, 2, 2)
 end
 
 local screenrow = function()
-  return helpers.call('screenrow')
+  return n.call('screenrow')
 end
 
 local screencol = function()
-  return helpers.call('screencol')
+  return n.call('screencol')
 end
 
 describe("'mousescroll'", function()
diff --git a/test/functional/options/num_options_spec.lua b/test/functional/options/num_options_spec.lua
index 0614bcf814..3ac6f3f121 100644
--- a/test/functional/options/num_options_spec.lua
+++ b/test/functional/options/num_options_spec.lua
@@ -1,8 +1,9 @@
 -- Tests for :setlocal and :setglobal
 
-local helpers = require('test.functional.helpers')(after_each)
-local clear, feed_command, eval, eq, api =
-  helpers.clear, helpers.feed_command, helpers.eval, helpers.eq, helpers.api
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
+
+local clear, feed_command, eval, eq, api = n.clear, n.feed_command, n.eval, t.eq, n.api
 
 local function should_fail(opt, value, errmsg)
   feed_command('setglobal ' .. opt .. '=' .. value)
@@ -12,7 +13,7 @@ local function should_fail(opt, value, errmsg)
   eq(errmsg, eval('v:errmsg'):match('E%d*'))
   feed_command('let v:errmsg = ""')
   local status, err = pcall(api.nvim_set_option_value, opt, value, {})
-  eq(status, false)
+  eq(false, status)
   eq(errmsg, err:match('E%d*'))
   eq('', eval('v:errmsg'))
 end
diff --git a/test/functional/options/shortmess_spec.lua b/test/functional/options/shortmess_spec.lua
index 6bc00ca1c5..dcbf9d15e0 100644
--- a/test/functional/options/shortmess_spec.lua
+++ b/test/functional/options/shortmess_spec.lua
@@ -1,10 +1,12 @@
-local helpers = require('test.functional.helpers')(after_each)
+local t = require('test.testutil')
+local n = require('test.functional.testnvim')()
 local Screen = require('test.functional.ui.screen')
-local clear = helpers.clear
-local command = helpers.command
-local eq = helpers.eq
-local eval = helpers.eval
-local feed = helpers.feed
+
+local clear = n.clear
+local command = n.command
+local eq = t.eq
+local eval = n.eval
+local feed = n.feed
 
 describe("'shortmess'", function()
   local screen
@@ -22,7 +24,7 @@ describe("'shortmess'", function()
       feed(':edit foo<CR>')
       screen:expect([[
         ^                                          |
-        ~                                         |*3
+        {1:~                                         }|*3
         "foo" [New]                               |
       ]])
       eq(1, eval('bufnr("%")'))
@@ -31,7 +33,7 @@ describe("'shortmess'", function()
       feed(':edit bar<CR>')
       screen:expect([[
         ^                                          |
-        ~                                         |*3
+        {1:~                                         }|*3
         :edit bar                                 |
       ]])
       eq(2, eval('bufnr("%")'))
@@ -43,21 +45,21 @@ describe("'shortmess'", function()
       feed(':edit foo<CR>')
       screen:expect([[
         ^                                          |
-        ~                                         |*3
+        {1:~                                         }|*3
         "foo" [New]                               |
       ]])
       eq(1, eval('bufnr("%")'))
       feed(':edit bar<CR>')
       screen:expect([[
         ^                                          |
-        ~                                         |*3
+        {1:~                                         }|*3
         "bar" [New]                               |
       ]])
       eq(2, eval('bufnr("%")'))
       feed(':bprevious<CR>')
       screen:expect([[
         ^                                          |
-        ~                                         |*3
+        {1:~                                         }|*3
         "foo" [New] --No lines in buffer--        |
       ]])
       eq(1, eval('bufnr("%")'))
@@ -66,14 +68,14 @@ describe("'shortmess'", function()
       feed(':bnext<CR>')
       screen:expect([[
         ^                                          |
-        ~                                         |*3
+        {1:~                                         }|*3
         :bnext                                    |
       ]])
       eq(2, eval('bufnr("%")'))
       feed(':bprevious<CR>')
       screen:expect([[
         ^                                          |
-        ~                                         |*3
+        {1:~                                         }|*3
         :bprevious                                |
       ]])
       eq(1, eval('bufnr("%")'))
diff --git a/test/functional/options/tabstop_spec.lua b/test/functional/options/tabstop_spec.lua
index 9070db8257..4ddbb13a0e 100644
--- a/test/functional/options/tabstop_spec.lua
+++ b/test/functional/options/tabstop_spec.lua
@@ -1,8 +1,8 @@
-local helpers = require('test.functional.helpers')(after_each)
+local n = require('test.functional.testnvim')()
 
-local assert_alive = helpers.assert_alive
-local clear = helpers.clear
-local feed = helpers.feed
+local assert_alive = n.assert_alive
+local clear = n.clear
+local feed = n.feed
 
 describe("'tabstop' option", function()
   before_each(function()
diff --git a/test/functional/options/winfixbuf_spec.lua b/test/functional/options/winfixbuf_spec.lua
new file mode 100644
index 0000000000..124f194b5a
--- /dev/null
+++ b/test/functional/options/winfixbuf_spec.lua
@@ -0,0 +1,55 @@
+local n = require('test.functional.testnvim')()
+
+local clear = n.clear
+local exec_lua = n.exec_lua
+
+describe("Nvim API calls with 'winfixbuf'", function()
+  before_each(function()
+    clear()
+  end)
+
+  it("Calling vim.api.nvim_win_set_buf with 'winfixbuf'", function()
+    local results = exec_lua([[
+      local function _setup_two_buffers()
+        local buffer = vim.api.nvim_create_buf(true, true)
+
+        vim.api.nvim_create_buf(true, true)  -- Make another buffer
+
+        local current_window = 0
+        vim.api.nvim_set_option_value("winfixbuf", true, {win=current_window})
+
+        return buffer
+      end
+
+      local other_buffer = _setup_two_buffers()
+      local current_window = 0
+      local results, _ = pcall(vim.api.nvim_win_set_buf, current_window, other_buffer)
+
+      return results
+    ]])
+
+    assert(results == false)
+  end)
+
+  it("Calling vim.api.nvim_set_current_buf with 'winfixbuf'", function()
+    local results = exec_lua([[
+      local function _setup_two_buffers()
+        local buffer = vim.api.nvim_create_buf(true, true)
+
+        vim.api.nvim_create_buf(true, true)  -- Make another buffer
+
+        local current_window = 0
+        vim.api.nvim_set_option_value("winfixbuf", true, {win=current_window})
+
+        return buffer
+      end
+
+      local other_buffer = _setup_two_buffers()
+      local results, _ = pcall(vim.api.nvim_set_current_buf, other_buffer)
+
+      return results
+    ]])
+
+    assert(results == false)
+  end)
+end)