8 files changed, 49 insertions, 10 deletions
diff --git a/test/functional/ex_cmds/encoding_spec.lua b/test/functional/ex_cmds/encoding_spec.lua
new file mode 100644
index 0000000000..997776ca25
--- /dev/null
+++ b/test/functional/ex_cmds/encoding_spec.lua
@@ -0,0 +1,40 @@
+local helpers = require('test.functional.helpers')
+local clear, execute, feed = helpers.clear, helpers.execute, helpers.feed
+local eq, neq, eval = helpers.eq, helpers.neq, helpers.eval
+
+describe('&encoding', function()
+
+  before_each(function()
+    clear()
+    -- sanity check: tests should run with encoding=utf-8
+    eq('utf-8', eval('&encoding'))
+    eq(3, eval('strwidth("Bär")'))
+  end)
+
+  it('cannot be changed after setup', function()
+    execute('set encoding=latin1')
+    -- error message expected
+    feed('<cr>')
+    neq(nil, string.find(eval('v:errmsg'), '^E905:'))
+    eq('utf-8', eval('&encoding'))
+    -- check nvim is still in utf-8 mode
+    eq(3, eval('strwidth("Bär")'))
+  end)
+
+  it('is not changed by `set all&`', function()
+    -- we need to set &encoding to something non-default
+    -- use 'latin1' when enc&vi is 'utf-8', 'utf-8' otherwise
+    execute('set fenc=default')
+    local enc_default, enc_other, width = eval('&fenc'), 'utf-8', 3
+    if enc_default == 'utf-8' then
+      enc_other = 'latin1'
+      width = 4 -- utf-8 string 'Bär' will count as 4 latin1 chars
+    end
+
+    clear('set enc=' .. enc_other)
+    execute('set all&')
+    eq(enc_other, eval('&encoding'))
+    eq(width, eval('strwidth("Bär")'))
+  end)
+
+end)
diff --git a/test/functional/helpers.lua b/test/functional/helpers.lua
index f228f6290c..6055cc3c59 100644
--- a/test/functional/helpers.lua
+++ b/test/functional/helpers.lua
@@ -7,7 +7,7 @@ local Session = require('nvim.session')
 
 local nvim_prog = os.getenv('NVIM_PROG') or 'build/bin/nvim'
 local nvim_argv = {nvim_prog, '-u', 'NONE', '-i', 'NONE', '-N',
-                   '--cmd', 'set shortmess+=I background=light noswapfile noautoindent laststatus=1',
+                   '--cmd', 'set shortmess+=I background=light noswapfile noautoindent laststatus=1 encoding=utf-8',
                    '--embed'}
 
 -- Formulate a path to the directory containing nvim.  We use this to
@@ -183,11 +183,16 @@ local function spawn(argv)
   return session
 end
 
-local function clear()
+local function clear(extra_cmd)
   if session then
     session:exit(0)
   end
-  session = spawn(nvim_argv)
+  local args = {unpack(nvim_argv)}
+  if extra_cmd ~= nil then
+    table.insert(args, '--cmd')
+    table.insert(args, extra_cmd)
+  end
+  session = spawn(args)
 end
 
 local function insert(...)
diff --git a/test/functional/legacy/044_099_regexp_multibyte_magic_spec.lua b/test/functional/legacy/044_099_regexp_multibyte_magic_spec.lua
index 58838e9d6e..efe61aa354 100644
--- a/test/functional/legacy/044_099_regexp_multibyte_magic_spec.lua
+++ b/test/functional/legacy/044_099_regexp_multibyte_magic_spec.lua
@@ -33,7 +33,6 @@ local function run_test_with_regexpengine(regexpengine)
     j 0123❤x
     k combinations]])
 
-  execute('set encoding=utf-8')
   execute('set re=' .. regexpengine)
 
   -- Lines 1-8. Exercise regexp search with various magic settings. On each
diff --git a/test/functional/legacy/075_maparg_spec.lua b/test/functional/legacy/075_maparg_spec.lua
index dac8940314..418abb14d4 100644
--- a/test/functional/legacy/075_maparg_spec.lua
+++ b/test/functional/legacy/075_maparg_spec.lua
@@ -10,7 +10,6 @@ describe('maparg()', function()
 
   it('is working', function()
     execute('set cpo-=<')
-    execute('set encoding=utf8')
 
     -- Test maparg() with a string result
     execute('map foo<C-V> is<F4>foo')
diff --git a/test/functional/legacy/082_string_comparison_spec.lua b/test/functional/legacy/082_string_comparison_spec.lua
index bd4e8a4d79..1615828ca0 100644
--- a/test/functional/legacy/082_string_comparison_spec.lua
+++ b/test/functional/legacy/082_string_comparison_spec.lua
@@ -9,7 +9,6 @@ describe('case-insensitive string comparison in UTF-8', function()
   setup(clear)
 
   it('is working', function()
-    execute('set enc=utf8')
     feed('ggdG<cr>')
     source([[
       function! Ch(a, op, b, expected)
diff --git a/test/functional/legacy/095_regexp_multibyte_spec.lua b/test/functional/legacy/095_regexp_multibyte_spec.lua
index a72fb669d2..559222e2ff 100644
--- a/test/functional/legacy/095_regexp_multibyte_spec.lua
+++ b/test/functional/legacy/095_regexp_multibyte_spec.lua
@@ -15,7 +15,7 @@ describe('regex with multi-byte', function()
       Results of test95:]])
 
     source([=[
-      set encoding=utf-8 nomore
+      set nomore
       let tl = []
 
       call add(tl, [2, '[[:alpha:][=a=]]\+', '879 aiaãâaiuvna ', 'aiaãâaiuvna'])
diff --git a/test/functional/legacy/mapping_spec.lua b/test/functional/legacy/mapping_spec.lua
index 0843506827..899f7423d0 100644
--- a/test/functional/legacy/mapping_spec.lua
+++ b/test/functional/legacy/mapping_spec.lua
@@ -12,8 +12,6 @@ describe('mapping', function()
       test starts here:
       ]])
 
-    execute('set encoding=utf-8')
-
     -- Abbreviations with р (0x80) should work.
     execute('inoreab чкпр   vim')
     feed('GAчкпр <esc>')
diff --git a/test/functional/legacy/utf8_spec.lua b/test/functional/legacy/utf8_spec.lua
index d26f436057..ef717042d0 100644
--- a/test/functional/legacy/utf8_spec.lua
+++ b/test/functional/legacy/utf8_spec.lua
@@ -10,7 +10,6 @@ describe('utf8', function()
   it('is working', function()
     insert('start:')
 
-    execute('set encoding=utf-8')
     execute('new')
     execute('call setline(1, ["aaa", "あああ", "bbb"])')