patch 8.2.3345: some code not covered by tests

Problem:    Some code not covered by tests.
Solution:   Add a few more tests. (Dominique Pellé, closes #8757)
diff --git a/src/testdir/test_spellfile.vim b/src/testdir/test_spellfile.vim
index c0852e0..3bb42a5 100644
--- a/src/testdir/test_spellfile.vim
+++ b/src/testdir/test_spellfile.vim
@@ -1016,6 +1016,33 @@
   call delete('XtestCOMMON-utf8.spl')
 endfunc
 
+" Test NOSUGGEST (see :help spell-COMMON)
+func Test_spellfile_NOSUGGEST()
+  call writefile(['2', 'foo/X', 'fog'], 'XtestNOSUGGEST.dic')
+  call writefile(['NOSUGGEST X'], 'XtestNOSUGGEST.aff')
+
+  mkspell! XtestNOSUGGEST-utf8.spl XtestNOSUGGEST
+  set spell spelllang=XtestNOSUGGEST-utf8.spl
+
+  for goodword in ['foo', 'Foo', 'FOO', 'fog', 'Fog', 'FOG']
+    call assert_equal(['', ''], spellbadword(goodword), goodword)
+  endfor
+  for badword in ['foO', 'fOO', 'fooo', 'foog', 'foofog', 'fogfoo']
+    call assert_equal([badword, 'bad'], spellbadword(badword))
+  endfor
+
+  call assert_equal(['fog'], spellsuggest('fooo', 1))
+  call assert_equal(['fog'], spellsuggest('fOo', 1))
+  call assert_equal(['fog'], spellsuggest('foG', 1))
+  call assert_equal(['fog'], spellsuggest('fogg', 1))
+
+  set spell& spelllang&
+  call delete('XtestNOSUGGEST.dic')
+  call delete('XtestNOSUGGEST.aff')
+  call delete('XtestNOSUGGEST-utf8.spl')
+endfunc
+
+
 " Test CIRCUMFIX (see: :help spell-CIRCUMFIX)
 func Test_spellfile_CIRCUMFIX()
   " Example taken verbatim from https://github.com/hunspell/hunspell/tree/master/tests