fix(notify): update refresh() to work inside fast events

Resolve #1341

doc/mini-notify.txt

@@ -327,6 +327,8 @@ Make notification window show relevant data:
   update its message.
 - Construct content from notifications and show them in a window.
 
+Note: effects are delayed if inside fast event (|vim.in_fast_event()|).
+
 ------------------------------------------------------------------------------
                                                               *MiniNotify.get()*
                              `MiniNotify.get`({id})

lua/mini/notify.lua

@@ -298,8 +298,7 @@ MiniNotify.make_notify = function(opts)
     if type(val.hl_group) ~= 'string' then H.error('`hl_group` in level data should be string.') end
   end
 
-  -- Use `vim.schedule_wrap` for output to be usable inside `vim.uv` callbacks
-  local notify = function(msg, level)
+  return function(msg, level)
     level = level or vim.log.levels.INFO
     local level_name = level_names[level]
     if level_name == nil then H.error('Only valid values of `vim.log.levels` are supported.') end
@@ -310,10 +309,6 @@ MiniNotify.make_notify = function(opts)
     local id = MiniNotify.add(msg, level_name, level_data.hl_group)
     vim.defer_fn(function() MiniNotify.remove(id) end, level_data.duration)
   end
-  return function(msg, level)
-    if not vim.in_fast_event() then return notify(msg, level) end
-    vim.schedule(function() notify(msg, level) end)
-  end
 end
 
 --- Add notification
@@ -417,7 +412,10 @@ end
 --- - Apply `config.content.format` to each element of notification array and
 ---   update its message.
 --- - Construct content from notifications and show them in a window.
+---
+--- Note: effects are delayed if inside fast event (|vim.in_fast_event()|).
 MiniNotify.refresh = function()
+  if vim.in_fast_event() then return vim.schedule(MiniNotify.refresh) end
   if H.is_disabled() or type(vim.v.exiting) == 'number' then return H.window_close() end
 
   -- Prepare array of active notifications

tests/test_notify.lua

@@ -258,7 +258,7 @@ T['make_notify()']['validates arguments'] = function()
   validate_level('OFF')
 end
 
-T['make_notify()']['has output working in `libuv` callbacks'] = function()
+T['make_notify()']['has output working in fast event'] = function()
   child.lua('_G.dur = ' .. small_time)
   child.lua([[
     vim.notify = MiniNotify.make_notify()
@@ -519,6 +519,17 @@ T['refresh()']['handles manual buffer/window delete'] = function()
   eq(is_notif_window_shown(), true)
 end
 
+T['refresh()']['can be used inside fast event'] = function()
+  add('Hello')
+  child.lua('_G.dur = ' .. small_time)
+  child.lua([[
+    local timer = vim.loop.new_timer()
+    timer:start(_G.dur, 0, function() MiniNotify.refresh() end)
+  ]])
+  sleep(small_time + small_time)
+  eq(child.cmd_capture('messages'), '')
+end
+
 T['refresh()']['respects `vim.{g,b}.mininotify_disable`'] = new_set({ parametrize = { { 'g' }, { 'b' } } }, {
   test = function(var_type)
     mock_gettimeofday()