diff --git a/src/testdir/test_signs.vim b/src/testdir/test_signs.vim
index 3a99a9b..abf70cd 100644
--- a/src/testdir/test_signs.vim
+++ b/src/testdir/test_signs.vim
@@ -248,8 +248,8 @@
                 \ 'SpellLocal SpellRare', @:)
   endfor
 
-  call writefile(repeat(["Sun is shining"], 30), "XsignOne")
-  call writefile(repeat(["Sky is blue"], 30), "XsignTwo")
+  call writefile(repeat(["Sun is shining"], 30), "XsignOne", 'D')
+  call writefile(repeat(["Sky is blue"], 30), "XsignTwo", 'D')
   call feedkeys(":sign define Sign icon=Xsig\<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"sign define Sign icon=XsignOne XsignTwo', @:)
 
@@ -326,8 +326,6 @@
   sign undefine Sign1
   sign undefine Sign2
   enew
-  call delete('XsignOne')
-  call delete('XsignTwo')
 endfunc
 
 func Test_sign_invalid_commands()
@@ -470,7 +468,7 @@
   call assert_fails('call sign_getdefined({})', 'E731:')
 
   " Tests for sign_place()
-  call writefile(repeat(["Sun is shining"], 30), "Xsign")
+  call writefile(repeat(["Sun is shining"], 30), "Xsign", 'D')
   edit Xsign
 
   call assert_equal(10, sign_place(10, '', 'sign1', 'Xsign',
@@ -576,7 +574,6 @@
 	      \ 'priority' : 10}]}],
 	      \ sign_getplaced('%', {'lnum' : 22}))
 
-  call delete("Xsign")
   call sign_unplace('*')
   call sign_undefine()
   enew | only
@@ -589,7 +586,7 @@
   call sign_unplace('*')
   call sign_undefine()
 
-  call writefile(repeat(["Sun is shining"], 30), "Xsign")
+  call writefile(repeat(["Sun is shining"], 30), "Xsign", 'D')
 
   let attr = {'text' : '=>', 'linehl' : 'Search', 'texthl' : 'Error'}
   call assert_equal(0, sign_define("sign1", attr))
@@ -829,7 +826,6 @@
   " Error cases
   call assert_fails("sign place 3 group= name=sign1 buffer=" . bnum, 'E474:')
 
-  call delete("Xsign")
   call sign_unplace('*')
   call sign_undefine()
   enew | only
@@ -872,8 +868,8 @@
   call sign_undefine()
 
   " Create two files and define signs
-  call writefile(repeat(["Sun is shining"], 30), "Xsign1")
-  call writefile(repeat(["It is beautiful"], 30), "Xsign2")
+  call writefile(repeat(["Sun is shining"], 30), "Xsign1", 'D')
+  call writefile(repeat(["It is beautiful"], 30), "Xsign2", 'D')
 
   let attr = {'text' : '=>', 'linehl' : 'Search', 'texthl' : 'Error'}
   call sign_define("sign1", attr)
@@ -1182,8 +1178,6 @@
   call sign_unplace('*')
   call sign_undefine()
   enew | only
-  call delete("Xsign1")
-  call delete("Xsign2")
 endfunc
 
 " Tests for auto-generating the sign identifier.
@@ -1195,7 +1189,7 @@
   let attr = {'text' : '=>', 'linehl' : 'Search', 'texthl' : 'Error'}
   call assert_equal(0, sign_define("sign1", attr))
 
-  call writefile(repeat(["Sun is shining"], 30), "Xsign")
+  call writefile(repeat(["Sun is shining"], 30), "Xsign", 'D')
   edit Xsign
 
   call assert_equal(1, sign_place(0, '', 'sign1', 'Xsign',
@@ -1217,7 +1211,6 @@
   call assert_equal(10,
 	      \ sign_getplaced('Xsign', {'id' : 1})[0].signs[0].lnum)
 
-  call delete("Xsign")
   call sign_unplace('*')
   call sign_undefine()
   enew | only
@@ -1235,7 +1228,7 @@
   call sign_define("sign3", attr)
 
   " Place three signs with different priority in the same line
-  call writefile(repeat(["Sun is shining"], 30), "Xsign")
+  call writefile(repeat(["Sun is shining"], 30), "Xsign", 'D')
   edit Xsign
 
   call sign_place(1, 'g1', 'sign1', 'Xsign',
@@ -1590,12 +1583,11 @@
   call sign_unplace('*')
   call sign_undefine()
   enew | only
-  call delete("Xsign")
 endfunc
 
 " Tests for memory allocation failures in sign functions
 func Test_sign_memfailures()
-  call writefile(repeat(["Sun is shining"], 30), "Xsign")
+  call writefile(repeat(["Sun is shining"], 30), "Xsign", 'D')
   edit Xsign
 
   call test_alloc_fail(GetAllocId('sign_getdefined'), 0, 0)
@@ -1632,7 +1624,6 @@
   call sign_unplace('*')
   call sign_undefine()
   enew | only
-  call delete("Xsign")
 endfunc
 
 " Test for auto-adjusting the line number of a placed sign.
@@ -1789,7 +1780,7 @@
 	redraw
    	sign place 10 line=2 name=s1
   END
-  call writefile(lines, 'XtestSigncolumn')
+  call writefile(lines, 'XtestSigncolumn', 'D')
   let buf = RunVimInTerminal('-S XtestSigncolumn', {'rows': 6})
   call VerifyScreenDump(buf, 'Test_sign_cursor_1', {})
 
@@ -1823,7 +1814,6 @@
 
   " clean up
   call StopVimInTerminal(buf)
-  call delete('XtestSigncolumn')
 endfunc
 
 " Return the 'len' characters in screen starting from (row,col)
@@ -1942,7 +1932,7 @@
 
 " Test for managing multiple signs using the sign functions
 func Test_sign_funcs_multi()
-  call writefile(repeat(["Sun is shining"], 30), "Xsign")
+  call writefile(repeat(["Sun is shining"], 30), "Xsign", 'D')
   edit Xsign
   let bnum = bufnr('')
 
@@ -2054,7 +2044,6 @@
   call sign_unplace('*')
   call sign_undefine()
   enew!
-  call delete("Xsign")
 endfunc
 
 func Test_sign_null_list()