fix(session): respect sessionoptions=terminal #19497

fixes #13078

Co-authored-by: Yuta Katayama <8683947+yutkat@users.noreply.github.com>

runtime/doc/options.txt

@@ -5112,7 +5112,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 
 						*'sessionoptions'* *'ssop'*
 'sessionoptions' 'ssop'	string	(default: "blank,buffers,curdir,folds,
-					       help,tabpages,winsize")
+					       help,tabpages,winsize,terminal")
 			global
 	Changes the effect of the |:mksession| command.  It is a comma-
 	separated list of words.  Each word enables saving and restoring

src/nvim/ex_session.c

@@ -193,6 +193,9 @@ static int ses_do_win(win_T *wp)
   if (bt_help(wp->w_buffer)) {
     return ssop_flags & SSOP_HELP;
   }
+  if (bt_terminal(wp->w_buffer)) {
+    return ssop_flags & SSOP_TERMINAL;
+  }
   return true;
 }
 
@@ -407,6 +410,8 @@ static int put_view(FILE *fd, win_T *wp, int add_edit, unsigned *flagp, int curr
     if ((flagp == &ssop_flags) && alt != NULL && alt->b_fname != NULL
         && *alt->b_fname != NUL
         && alt->b_p_bl
+        // do not set balt if buffer is terminal and "terminal" is not set in options
+        && !(bt_terminal(alt) && !(ssop_flags & SSOP_TERMINAL))
         && (fputs("balt ", fd) < 0
             || ses_fname(fd, alt, flagp, true) == FAIL)) {
       return FAIL;
@@ -616,6 +621,7 @@ static int makeopens(FILE *fd, char_u *dirnow)
   FOR_ALL_BUFFERS(buf) {
     if (!(only_save_windows && buf->b_nwindows == 0)
         && !(buf->b_help && !(ssop_flags & SSOP_HELP))
+        && !(bt_terminal(buf) && !(ssop_flags & SSOP_TERMINAL))
         && buf->b_fname != NULL
         && buf->b_p_bl) {
       if (fprintf(fd, "badd +%" PRId64 " ",

src/nvim/options.lua

@@ -2063,7 +2063,7 @@ return {
       type='string', list='onecomma', scope={'global'},
       deny_duplicates=true,
       varname='p_ssop',
-      defaults={if_true="blank,buffers,curdir,folds,help,tabpages,winsize"}
+      defaults={if_true="blank,buffers,curdir,folds,help,tabpages,winsize,terminal"}
     },
     {
       full_name='shada', abbreviation='sd',

test/functional/ex_cmds/mksession_spec.lua

@@ -53,6 +53,73 @@ describe(':mksession', function()
     neq(funcs.winbufnr(1), funcs.winbufnr(3))
   end)
 
+  -- common testing procedure for testing "sessionoptions-=terminal"
+  local function test_terminal_session_disabled(expected_buf_count)
+    command('set sessionoptions-=terminal')
+
+    command('mksession ' .. session_file)
+
+    -- Create a new test instance of Nvim.
+    clear()
+
+    -- Restore session.
+    command('source ' .. session_file)
+
+    eq(expected_buf_count, #meths.list_bufs())
+  end
+
+  it(
+    'do not restore :terminal if not set in sessionoptions, terminal in current window #13078',
+    function()
+      local tmpfile_base = file_prefix .. '-tmpfile'
+      command('edit ' .. tmpfile_base)
+      command('terminal')
+
+      local buf_count = #meths.list_bufs()
+      eq(2, buf_count)
+
+      eq('terminal', meths.buf_get_option(0, 'buftype'))
+
+      test_terminal_session_disabled(2)
+
+      -- no terminal should be set. As a side effect we end up with a blank buffer
+      eq('', meths.buf_get_option(meths.list_bufs()[1], 'buftype'))
+      eq('', meths.buf_get_option(meths.list_bufs()[2], 'buftype'))
+    end
+  )
+
+  it('do not restore :terminal if not set in sessionoptions, terminal hidden #13078', function()
+    command('terminal')
+    local terminal_bufnr = meths.get_current_buf()
+
+    local tmpfile_base = file_prefix .. '-tmpfile'
+    -- make terminal hidden by opening a new file
+    command('edit ' .. tmpfile_base .. '1')
+
+    local buf_count = #meths.list_bufs()
+    eq(2, buf_count)
+
+    eq(1, funcs.getbufinfo(terminal_bufnr)[1].hidden)
+
+    test_terminal_session_disabled(1)
+
+    -- no terminal should exist here
+    neq('', meths.buf_get_name(meths.list_bufs()[1]))
+  end)
+
+  it('do not restore :terminal if not set in sessionoptions, only buffer #13078', function()
+    command('terminal')
+    eq('terminal', meths.buf_get_option(0, 'buftype'))
+
+    local buf_count = #meths.list_bufs()
+    eq(1, buf_count)
+
+    test_terminal_session_disabled(1)
+
+    -- no terminal should be set
+    eq('', meths.buf_get_option(0, 'buftype'))
+  end)
+
   it('restores tab-local working directories', function()
     local tmpfile_base = file_prefix .. '-tmpfile'
     local cwd_dir = funcs.getcwd()
@@ -179,7 +246,7 @@ describe(':mksession', function()
       height = 3,
       row = 0,
       col = 1,
-      style = 'minimal'
+      style = 'minimal',
     }
     meths.open_win(buf, false, config)
     local cmdheight = meths.get_option('cmdheight')