test: resolve symlink in popup window

Makefile

@@ -17,6 +17,7 @@ clean:
 test: test/vader.vim
 	@cd test && $(VIM) $(VIM_FLAGS)                                      -c 'Vader! symlink.vader'
 	@cd test && $(VIM) $(VIM_FLAGS) -R                                   -c 'Vader! symlink.vader'
+	@cd test && $(VIM) $(VIM_FLAGS)                                      -c 'Vader! symlink-edit-in-popup.vader'
 	@cd test && $(VIM) $(VIM_FLAGS) -o fixture/foo.link fixture/bar.link -c 'Vader! symlink-split-horizontal.vader'
 	@cd test && $(VIM) $(VIM_FLAGS) -O fixture/foo.link fixture/bar.link -c 'Vader! symlink-split-vertical.vader'
 	@cd test && $(VIM) $(VIM_FLAGS) -d fixture/foo.link fixture/bar.link -c 'Vader! symlink-split-vertical.vader'

test/fixture/tagged.original.vim

@@ -0,0 +1 @@
+command! Foo :

test/fixture/tagged/tagged.link.vim

@@ -0,0 +1 @@
+../tagged.original.vim

test/fixture/tagged/tags

@@ -0,0 +1,32 @@
+!_TAG_EXTRA_DESCRIPTION	anonymous	/Include tags for non-named objects like lambda/
+!_TAG_EXTRA_DESCRIPTION	fileScope	/Include tags of file scope/
+!_TAG_EXTRA_DESCRIPTION	pseudo	/Include pseudo tags/
+!_TAG_EXTRA_DESCRIPTION	subparser	/Include tags generated by subparsers/
+!_TAG_FIELD_DESCRIPTION	epoch	/the last modified time of the input file (only for F\/file kind tag)/
+!_TAG_FIELD_DESCRIPTION	file	/File-restricted scoping/
+!_TAG_FIELD_DESCRIPTION	input	/input file/
+!_TAG_FIELD_DESCRIPTION	name	/tag name/
+!_TAG_FIELD_DESCRIPTION	pattern	/pattern/
+!_TAG_FIELD_DESCRIPTION	typeref	/Type and name of a variable or typedef/
+!_TAG_FILE_FORMAT	2	/extended format; --format=1 will not append ;" to lines/
+!_TAG_FILE_SORTED	1	/0=unsorted, 1=sorted, 2=foldcase/
+!_TAG_KIND_DESCRIPTION!Vim	C,constant	/constant definitions/
+!_TAG_KIND_DESCRIPTION!Vim	a,augroup	/autocommand groups/
+!_TAG_KIND_DESCRIPTION!Vim	c,command	/user-defined commands/
+!_TAG_KIND_DESCRIPTION!Vim	f,function	/function definitions/
+!_TAG_KIND_DESCRIPTION!Vim	k,class	/vim9script classes/
+!_TAG_KIND_DESCRIPTION!Vim	m,map	/maps/
+!_TAG_KIND_DESCRIPTION!Vim	n,filename	/vimball filename/
+!_TAG_KIND_DESCRIPTION!Vim	v,variable	/variable definitions/
+!_TAG_OUTPUT_EXCMD	mixed	/number, pattern, mixed, or combineV2/
+!_TAG_OUTPUT_FILESEP	slash	/slash or backslash/
+!_TAG_OUTPUT_MODE	u-ctags	/u-ctags or e-ctags/
+!_TAG_OUTPUT_VERSION	1.1	/current.age/
+!_TAG_PARSER_VERSION!Vim	1.1	/current.age/
+!_TAG_PATTERN_LENGTH_LIMIT	96	/0 for no limit/
+!_TAG_PROC_CWD	/home/aileot/.local/share/nvim/lazy/vim-symlink/test/fixture/tagged/	//
+!_TAG_PROGRAM_AUTHOR	Universal Ctags Team	//
+!_TAG_PROGRAM_NAME	Universal Ctags	/Derived from Exuberant Ctags/
+!_TAG_PROGRAM_URL	https://ctags.io/	/official site/
+!_TAG_PROGRAM_VERSION	6.2.0	//
+Foo	tagged.link.vim	/^command! Foo :$/;"	c

test/symlink-edit-in-popup.vader

@@ -0,0 +1,16 @@
+Before:
+  execute 'cd' fnameescape(fnamemodify(g:vader_file, ':p:h'))
+
+" It should follow the symlinks for every file
+Execute (skip the 2 Vader.vim buffers):
+  quit!
+  quit!
+
+Then (opening a symlinked file to a popup window):
+  if !has('&previewpopup')
+    finish
+  endif
+  set previewpopup=height:10,width:60
+  execute 'set tags='.. fnamemodify(g:vader_file, ':p:h') ..'/fixture/tagged/tags'
+  ptag Foo
+  AssertEqual 'fixture/tagged.original.vim', bufname('$')