patch 8.2.0243: insufficient code coverage for ex_docmd.c functions

Problem:    Insufficient code coverage for ex_docmd.c functions.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #5618)
diff --git a/src/testdir/test_window_cmd.vim b/src/testdir/test_window_cmd.vim
index cbd08c9..24501e1 100644
--- a/src/testdir/test_window_cmd.vim
+++ b/src/testdir/test_window_cmd.vim
@@ -942,4 +942,18 @@
   only!
 endfunc
 
+" Test for errors with :wincmd
+func Test_wincmd_errors()
+  call assert_fails('wincmd g', 'E474:')
+  call assert_fails('wincmd ab', 'E474:')
+endfunc
+
+" Test for errors with :winpos
+func Test_winpos_errors()
+  if !has("gui_running") && !has('win32')
+    call assert_fails('winpos', 'E188:')
+  endif
+  call assert_fails('winpos 10', 'E466:')
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab