patch 8.2.1053: insufficient testing for 'statusline' and 'tabline'

Problem:    Insufficient testing for 'statusline' and 'tabline'.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #6333)
diff --git a/src/testdir/test_statusline.vim b/src/testdir/test_statusline.vim
index 708686b..f73998a 100644
--- a/src/testdir/test_statusline.vim
+++ b/src/testdir/test_statusline.vim
@@ -1,10 +1,7 @@
 " Test 'statusline'
 "
 " Not tested yet:
-"   %a
 "   %N
-"   %T
-"   %X
 
 source view_util.vim
 source check.vim
@@ -105,6 +102,18 @@
   set statusline=%F
   call assert_match('/testdir/Xstatusline\s*$', s:get_statusline())
 
+  " Test for min and max width with %(. For some reason, if this test is moved
+  " after the below test for the help buffer flag, then the code to truncate
+  " the string is not executed.
+  set statusline=%015(%f%)
+  call assert_match('^    Xstatusline\s*$', s:get_statusline())
+  set statusline=%.6(%f%)
+  call assert_match('^<sline\s*$', s:get_statusline())
+  set statusline=%14f
+  call assert_match('^   Xstatusline\s*$', s:get_statusline())
+  set statusline=%.4L
+  call assert_match('^10>3\s*$', s:get_statusline())
+
   " %h: Help buffer flag, text is "[help]".
   " %H: Help buffer flag, text is ",HLP".
   set statusline=%h,%H
@@ -423,3 +432,5 @@
   call StopVimInTerminal(buf)
   call delete('XTest_statusline')
 endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab