Add test that tries loading the script twice

Author: axelf4

plugin/strip_trailing_whitespace.vim

@@ -3,7 +3,7 @@ let s:save_cpo = &cpo | set cpo&vim
 
 " Only load the plugin once
 if exists('g:loaded_strip_trailing_whitespace')
-    finish
+	finish
 endif
 let g:loaded_strip_trailing_whitespace = 1
 

runtest.vim

@@ -1,10 +1,10 @@
 let s:has_errors = 0
 
 try
-	let s:scriptdir = fnamemodify(resolve(expand('<sfile>:p')), ':h')
-	execute 'source' s:scriptdir .. '/plugin/strip_trailing_whitespace.vim'
+	execute 'cd' fnamemodify(resolve(expand('<sfile>:p')), ':h')
+	execute 'source' 'plugin/strip_trailing_whitespace.vim'
 
-	let s:testfiles = glob(s:scriptdir .. '/test/*.vim', 1, 1)
+	let s:testfiles = glob('test/*.vim', 1, 1)
 	for s:testfile in s:testfiles
 		execute 'source' s:testfile
 

test/test.vim

@@ -74,3 +74,7 @@ function Test_HandleManyLinesWithTWS() abort
 	endfunction
 	call s:TestEdits(['line '], function('s:EditCb'), extend(['line'], repeat([''], 100)))
 endfunction
+
+function Test_LoadScriptTwice() abort
+	source plugin/strip_trailing_whitespace.vim
+endfunction