feat(defaults): store spellfile in stdpath('data') #33048

Problem:
First rtp directory is unpredictable and not in line with XDG
base spec.

Solution:
Use stdpath('data')/spell as directory if 'spellfile' is not set.

Co-authored-by: zeertzjq <zeertzjq@outlook.com>
Co-authored-by: Justin M. Keyes <justinkz@gmail.com>

2 files changed, 27 insertions, 1 deletions

diff --git a/test/functional/core/spellfile_spec.lua b/test/functional/core/spellfile_spec.lua
index e2ccb038e7..96841f030e 100644
--- a/test/functional/core/spellfile_spec.lua
+++ b/test/functional/core/spellfile_spec.lua
@@ -14,7 +14,7 @@ local testdir = 'Xtest-functional-spell-spellfile.d'
 
 describe('spellfile', function()
   before_each(function()
-    clear()
+    clear({ env = { XDG_DATA_HOME = testdir .. '/xdg_data' } })
     rmdir(testdir)
     mkdir(testdir)
     mkdir(testdir .. '/spell')
@@ -117,4 +117,29 @@ describe('spellfile', function()
     local fname = fn.fnamemodify(testdir .. '/spell/spell.add', ':p')
     api.nvim_set_option_value('spellfile', fname, {})
   end)
+
+  describe('default location', function()
+    it("is stdpath('data')/spell/en.utf-8.add", function()
+      n.command('set spell')
+      n.insert('abc')
+      n.feed('zg')
+      eq(
+        t.fix_slashes(fn.stdpath('data') .. '/spell/en.utf-8.add'),
+        t.fix_slashes(api.nvim_get_option_value('spellfile', {}))
+      )
+    end)
+
+    it("is not set if stdpath('data') is not writable", function()
+      n.command('set spell')
+      fn.writefile({ '' }, testdir .. '/xdg_data')
+      n.insert('abc')
+      eq("Vim(normal):E764: Option 'spellfile' is not set", exc_exec('normal! zg'))
+    end)
+
+    it("is not set if 'spelllang' is not set", function()
+      n.command('set spell spelllang=')
+      n.insert('abc')
+      eq("Vim(normal):E764: Option 'spellfile' is not set", exc_exec('normal! zg'))
+    end)
+  end)
 end)
diff --git a/test/old/testdir/test_spellfile.vim b/test/old/testdir/test_spellfile.vim
index f356b12370..351ffc9612 100644
--- a/test/old/testdir/test_spellfile.vim
+++ b/test/old/testdir/test_spellfile.vim
@@ -1123,6 +1123,7 @@ endfunc
 " When 'spellfile' is not set, adding a new good word will automatically set
 " the 'spellfile'
 func Test_init_spellfile()
+  throw 'Skipped: Nvim defaults spellfile to stdpath("data")/spell/'
   let save_rtp = &rtp
   let save_encoding = &encoding
   call mkdir('Xrtp/spell', 'pR')