patch 9.0.0881: cannot get the currently showing mouse shape

Problem:    Cannot get the currently showing mouse shape.
Solution:   Add getmouseshape().
diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index cb07221..6f109e8 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -2890,6 +2890,12 @@
   bwipe!
 endfunc
 
+func Test_getmouseshape()
+  CheckFeature mouseshape
+
+  call assert_equal('arrow', getmouseshape())
+endfunc
+
 " Test for glob()
 func Test_glob()
   call assert_equal('', glob(test_null_string()))