diff --git a/src/testdir/test_usercommands.vim b/src/testdir/test_usercommands.vim
index c38424f..93312f1 100644
--- a/src/testdir/test_usercommands.vim
+++ b/src/testdir/test_usercommands.vim
@@ -270,6 +270,8 @@
   call assert_fails('com! -complete=custom DoCmd :', 'E467:')
   call assert_fails('com! -complete=customlist DoCmd :', 'E467:')
   call assert_fails('com! -complete=behave,CustomComplete DoCmd :', 'E468:')
+  call assert_fails('com! -complete=file DoCmd :', 'E1208:')
+  call assert_fails('com! -nargs=0 -complete=file DoCmd :', 'E1208:')
   call assert_fails('com! -nargs=x DoCmd :', 'E176:')
   call assert_fails('com! -count=1 -count=2 DoCmd :', 'E177:')
   call assert_fails('com! -count=x DoCmd :', 'E178:')
@@ -338,34 +340,30 @@
   call feedkeys(":com DoC\<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"com DoC', @:)
 
-  com! -complete=behave DoCmd :
+  com! -nargs=1 -complete=behave DoCmd :
   call feedkeys(":DoCmd \<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"DoCmd mswin xterm', @:)
 
-  " This does not work. Why?
-  "call feedkeys(":DoCmd x\<C-A>\<C-B>\"\<CR>", 'tx')
-  "call assert_equal('"DoCmd xterm', @:)
-
-  com! -complete=custom,CustomComplete DoCmd :
+  com! -nargs=* -complete=custom,CustomComplete DoCmd :
   call feedkeys(":DoCmd \<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"DoCmd January February Mars', @:)
 
-  com! -complete=customlist,CustomCompleteList DoCmd :
+  com! -nargs=? -complete=customlist,CustomCompleteList DoCmd :
   call feedkeys(":DoCmd \<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"DoCmd Monday Tuesday Wednesday', @:)
 
-  com! -complete=custom,CustomCompleteList DoCmd :
+  com! -nargs=+ -complete=custom,CustomCompleteList DoCmd :
   call assert_fails("call feedkeys(':DoCmd \<C-D>', 'tx')", 'E730:')
 
-  com! -complete=customlist,CustomComp DoCmd :
+  com! -nargs=+ -complete=customlist,CustomComp DoCmd :
   call assert_fails("call feedkeys(':DoCmd \<C-D>', 'tx')", 'E117:')
 
   " custom completion without a function
-  com! -complete=custom, DoCmd
+  com! -nargs=? -complete=custom, DoCmd
   call assert_beeps("call feedkeys(':DoCmd \t', 'tx')")
 
   " custom completion failure with the wrong function
-  com! -complete=custom,min DoCmd
+  com! -nargs=? -complete=custom,min DoCmd
   call assert_fails("call feedkeys(':DoCmd \t', 'tx')", 'E118:')
 
   delcom DoCmd
@@ -500,21 +498,21 @@
         \           execute('command DoCmd'))
 
   " Test with various -complete= argument values (non-exhaustive list)
-  command! -complete=arglist DoCmd :
+  command! -nargs=1 -complete=arglist DoCmd :
   call assert_equal("\n    Name              Args Address Complete    Definition"
-        \        .. "\n    DoCmd             0            arglist     :",
+        \        .. "\n    DoCmd             1            arglist     :",
         \           execute('command DoCmd'))
-  command! -complete=augroup DoCmd :
+  command! -nargs=* -complete=augroup DoCmd :
   call assert_equal("\n    Name              Args Address Complete    Definition"
-        \        .. "\n    DoCmd             0            augroup     :",
+        \        .. "\n    DoCmd             *            augroup     :",
         \           execute('command DoCmd'))
-  command! -complete=custom,CustomComplete DoCmd :
+  command! -nargs=? -complete=custom,CustomComplete DoCmd :
   call assert_equal("\n    Name              Args Address Complete    Definition"
-        \        .. "\n    DoCmd             0            custom      :",
+        \        .. "\n    DoCmd             ?            custom      :",
         \           execute('command DoCmd'))
-  command! -complete=customlist,CustomComplete DoCmd :
+  command! -nargs=+ -complete=customlist,CustomComplete DoCmd :
   call assert_equal("\n    Name              Args Address Complete    Definition"
-        \        .. "\n    DoCmd             0            customlist  :",
+        \        .. "\n    DoCmd             +            customlist  :",
         \           execute('command DoCmd'))
 
   " Test with various -narg= argument values.