(mini.deps) Update add() to source 'after/plugin' when needed.

Details:
- As `:packadd` only puts '/after' directory to 'runtimepath' but not
  executes scripts from there, make sure that they are sourced.
  This makes difference when `add()` is called not during startup (for
  example, lazy loaded with `later()`).
  Looks like plugins should not be using 'after/plugin' directory,
  though, in favor of just 'plugin' (but they might).

Author: echasnovski

doc/mini-deps.txt

@@ -424,6 +424,7 @@ Add plugin to current session
     - Execute `opts.hooks.post_install`.
 - Register spec(s) in current session.
 - Make sure plugin(s) can be used in current session (see |:packadd|).
+- If not during startup and is needed, source all "after/plugin/" scripts.
 
 Notes:
 - Presence of plugin is checked by its name which is the same as the name

lua/mini/deps.lua

@@ -440,6 +440,7 @@ MiniDeps.config = {
 ---     - Execute `opts.hooks.post_install`.
 --- - Register spec(s) in current session.
 --- - Make sure plugin(s) can be used in current session (see |:packadd|).
+--- - If not during startup and is needed, source all "after/plugin/" scripts.
 ---
 --- Notes:
 --- - Presence of plugin is checked by its name which is the same as the name
@@ -490,6 +491,19 @@ MiniDeps.add = function(spec, opts)
     -- Add to 'runtimepath'
     vim.cmd(cmd .. p.name)
   end
+
+  -- Execute 'after/' scripts if not during startup (when they will be sourced
+  -- automatically), as `:packadd` only sources plain 'plugin/' files.
+  -- See https://github.com/vim/vim/issues/1994.
+  -- Deliberately do so after executing all currently known 'plugin/' files.
+  local should_load_after_dir = vim.v.vim_did_enter == 1 and not opts.bang and vim.o.loadplugins
+  if not should_load_after_dir then return end
+  for _, p in ipairs(plugs) do
+    -- NOTE: This sources first lua and then vim, not how it is done during
+    -- startup (`:h loadplugins`) for speed (one `glob()` instead of two).
+    local after_paths = vim.fn.glob(p.path .. '/after/plugin/**/*.{vim,lua}', false, true)
+    vim.tbl_map(H.source, after_paths)
+  end
 end
 
 --- Update plugins
@@ -1512,6 +1526,10 @@ H.readdir = function(path)
   return vim.tbl_map(function(x) return path .. '/' .. x end, vim.fn.readdir(path))
 end
 
+H.source = function(path)
+  pcall(function() vim.cmd('source ' .. vim.fn.fnameescape(path)) end)
+end
+
 H.buf_set_name = function(buf_id, name)
   local n = (H.buf_name_counts[name] or 0) + 1
   H.buf_name_counts[name] = n

tests/dir-deps/pack/deps/opt/plugin_1/after/plugin/plug_1.lua

@@ -0,0 +1,2 @@
+_G.plugin_log = _G.plugin_log or {}
+table.insert(_G.plugin_log, 'after/plugin/plug_1.lua')

tests/dir-deps/pack/deps/opt/plugin_1/after/plugin/plug_1.nonlua

@@ -0,0 +1 @@
+error()

tests/dir-deps/pack/deps/opt/plugin_1/after/plugin/plug_1.vim

@@ -0,0 +1,5 @@
+lua <<EOF
+_G.plugin_log = _G.plugin_log or {}
+table.insert(_G.plugin_log, 'after/plugin/plug_1.vim')
+EOF
+

tests/dir-deps/pack/deps/opt/plugin_1/after/plugin/subdir/plug_1_sub.lua

@@ -0,0 +1,2 @@
+_G.plugin_log = _G.plugin_log or {}
+table.insert(_G.plugin_log, 'after/plugin/subdir/plug_1_sub.lua')

tests/dir-deps/pack/deps/opt/plugin_1/plugin/plug_1.lua

@@ -1 +1,2 @@
-_G.plugin_1_plugin_dir_was_sourced = true
+_G.plugin_log = _G.plugin_log or {}
+table.insert(_G.plugin_log, 'plugin/plug_1.lua')

tests/dir-deps/pack/deps/opt/plugin_1/plugin/plug_1.vim

@@ -0,0 +1,5 @@
+lua <<EOF
+_G.plugin_log = _G.plugin_log or {}
+table.insert(_G.plugin_log, 'plugin/plug_1.vim')
+EOF
+

tests/dir-deps/pack/deps/opt/plugin_1/plugin/subdir/plug_1_sub.lua

@@ -0,0 +1,2 @@
+_G.plugin_log = _G.plugin_log or {}
+table.insert(_G.plugin_log, 'plugin/subdir/plug_1_sub.lua')

tests/dir-deps/pack/deps/opt/plugin_2/after/plugin/plug_2.lua

@@ -0,0 +1,2 @@
+_G.plugin_log = _G.plugin_log or {}
+table.insert(_G.plugin_log, 'after/plugin/plug_2.lua')

tests/dir-deps/pack/deps/opt/plugin_2/plugin/plug_2.lua

@@ -0,0 +1,2 @@
+_G.plugin_log = _G.plugin_log or {}
+table.insert(_G.plugin_log, 'plugin/plug_2.lua')

tests/test_deps.lua

@@ -289,8 +289,13 @@ T['add()']['works for present plugins'] = new_set({ parametrize = { { 'plugin_1'
     -- No CLI process should be run as plugin is already present
     eq(get_spawn_log(), {})
 
-    -- Should use `:packadd`, i.e. load 'plugin/', 'ftdetect/', etc.
-    eq(child.lua_get('_G.plugin_1_plugin_dir_was_sourced'), true)
+    -- Should add plugin to 'runtimepath'
+    local rtp = vim.split(child.o.runtimepath, ',')
+    eq(vim.tbl_contains(rtp, ref_path), true)
+    eq(vim.tbl_contains(rtp, ref_path .. '/after'), true)
+
+    -- Should load 'plugin/', 'after/plugin/', etc.
+    eq(child.lua_get('type(_G.plugin_log)'), 'table')
   end,
 })
 
@@ -313,6 +318,47 @@ T['add()']['infers name from source'] = new_set({
   end,
 })
 
+T['add()']["properly sources 'plugin/' and 'after/plugin/'"] = function()
+  add({ name = 'plugin_1', depends = { 'plugin_2' } })
+  local after_paths = { 'after/plugin/plug_1.lua', 'after/plugin/plug_1.vim', 'after/plugin/subdir/plug_1_sub.lua' }
+  if child.fn.has('nvim-0.9') == 0 then
+    after_paths = { 'after/plugin/plug_1.vim', 'after/plugin/plug_1.lua', 'after/plugin/subdir/plug_1_sub.lua' }
+  end
+  --stylua: ignore
+  local ref_plugin_log = {
+          'plugin/plug_2.lua',
+          'plugin/plug_1.vim', 'plugin/plug_1.lua', 'plugin/subdir/plug_1_sub.lua',
+    'after/plugin/plug_2.lua',
+    unpack(after_paths)
+  }
+  eq(child.lua_get('_G.plugin_log'), ref_plugin_log)
+end
+
+T['add()']["does not source 'after/plugin/' when not needed"] = function()
+  -- During startup
+  local setup_cmd =
+    string.format("lua require('mini.deps').setup({ path = { package = %s } })", vim.inspect(test_dir_absolute))
+  child.restart({ '-u', 'NONE', '--cmd', 'set rtp+=.', '--cmd', setup_cmd, '--cmd', "lua MiniDeps.add('plugin_1')" })
+
+  --stylua: ignore
+  eq(child.lua_get('_G.plugin_log'), {
+    -- 'plugin/' directory gets sourced both as part of startup and `:packadd`
+          'plugin/plug_1.vim',       'plugin/plug_1.lua',       'plugin/subdir/plug_1_sub.lua',
+          'plugin/plug_1.vim',       'plugin/plug_1.lua',       'plugin/subdir/plug_1_sub.lua',
+    -- But sourcing 'after/plugin/' in 'mini.deps' should not duplicate startup
+    'after/plugin/plug_1.vim', 'after/plugin/plug_1.lua', 'after/plugin/subdir/plug_1_sub.lua',
+  })
+
+  -- When 'loadplugins = false'
+  child.restart({ '-u', 'NONE', '--cmd', 'set rtp+=.', '--cmd', setup_cmd })
+  child.o.loadplugins = false
+  add('plugin_1')
+
+  -- - `:packadd` does not recognize 'loadplugins' and thus sources them
+  --   But 'after/plugin/' should not be sourced
+  eq(child.lua_get('_G.plugin_log'), { 'plugin/plug_1.vim', 'plugin/plug_1.lua', 'plugin/subdir/plug_1_sub.lua' })
+end
+
 T['add()']['can update session data'] = function()
   add('plugin_1')
   add('plugin_2')
@@ -440,7 +486,7 @@ end
 
 T['add()']['respects `opts.bang`'] = function()
   add('plugin_1', { bang = true })
-  eq(child.lua_get('_G.plugin_1_plugin_dir_was_sourced'), vim.NIL)
+  eq(child.lua_get('_G.plugin_log'), vim.NIL)
 end
 
 T['add()']['does not modify input'] = function()