patch 8.1.0926: no test for :wnext, :wNext and :wprevious

Problem:    No test for :wnext, :wNext and :wprevious.
Solution:   Add a test. (Dominique Pelle, closes #3963)
diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index 2ca5f2b..92e2ae3 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -269,6 +269,7 @@
 	test_window_cmd \
 	test_window_id \
 	test_windows_home \
+	test_wnext \
 	test_wordcount \
 	test_writefile \
 	test_xxd \
diff --git a/src/testdir/test_alot.vim b/src/testdir/test_alot.vim
index 81873af..204796a 100644
--- a/src/testdir/test_alot.vim
+++ b/src/testdir/test_alot.vim
@@ -66,3 +66,4 @@
 source test_unlet.vim
 source test_virtualedit.vim
 source test_window_cmd.vim
+source test_wnext.vim
diff --git a/src/testdir/test_wnext.vim b/src/testdir/test_wnext.vim
new file mode 100644
index 0000000..3df61ce
--- /dev/null
+++ b/src/testdir/test_wnext.vim
@@ -0,0 +1,101 @@
+" Test :wnext :wNext and :wprevious
+
+func Test_wnext()
+  args X1 X2
+
+  call setline(1, '1')
+  wnext
+  call assert_equal(['1'], readfile('X1'))
+  call assert_equal('X2', bufname('%'))
+
+  call setline(1, '2')
+  call assert_fails('wnext', 'E165:')
+  call assert_equal(['2'], readfile('X2'))
+  call assert_equal('X2', bufname('%'))
+
+  " Test :wnext with a single file.
+  args X1
+  call assert_equal('X1', bufname('%'))
+  call assert_fails('wnext', 'E163:')
+
+  " Test :wnext with a count.
+  args X1 X2 X3
+  call assert_equal('X1', bufname('%'))
+  2wnext
+  call assert_equal('X3', bufname('%'))
+
+  " Test :wnext {file}.
+  args X1 X2 X3
+  wnext X4
+  call assert_equal(['1'], readfile('X4'))
+  call assert_equal('X2', bufname('%'))
+  call assert_fails('wnext X4', 'E13:')
+  call assert_equal(['1'], readfile('X4'))
+  wnext! X4
+  call assert_equal(['2'], readfile('X4'))
+  call assert_equal('X3', bufname('%'))
+
+  args X1 X2
+  " Commented out as, E13 occurs on Windows instead of E17
+  "call assert_fails('wnext .', 'E17:')
+  call assert_fails('wnext! .', 'E502:')
+
+  %bwipe!
+  call delete('X1')
+  call delete('X2')
+  call delete('X3')
+  call delete('X4')
+endfunc
+
+func Test_wprevious()
+  args X1 X2
+
+  next
+  call assert_equal('X2', bufname('%'))
+  call setline(1, '2')
+  wprevious
+  call assert_equal(['2'], readfile('X2'))
+  call assert_equal('X1', bufname('%'))
+
+  call setline(1, '1')
+  call assert_fails('wprevious', 'E164:')
+  call assert_fails('wNext', 'E164:')
+
+  " Test :wprevious with a single file.
+  args X1
+  call assert_fails('wprevious', 'E163:')
+  call assert_fails('wNext', 'E163:')
+
+  " Test :wprevious with a count.
+  args X1 X2 X3
+  2next
+  call setline(1, '3')
+  call assert_equal('X3', bufname('%'))
+  2wprevious
+  call assert_equal('X1', bufname('%'))
+  call assert_equal(['3'], readfile('X3'))
+
+  " Test :wprevious {file}
+  args X1 X2 X3
+  2next
+  call assert_equal('X3', bufname('%'))
+  wprevious X4
+  call assert_equal(['3'], readfile('X4'))
+  call assert_equal('X2', bufname('%'))
+  call assert_fails('wprevious X4', 'E13:')
+  call assert_equal(['3'], readfile('X4'))
+  wprevious! X4
+  call assert_equal(['2'], readfile('X4'))
+  call assert_equal('X1', bufname('%'))
+
+  args X1 X2
+  " Commented out as, E13 occurs on Windows instead of E17
+  "call assert_fails('wprevious .', 'E17:')
+  call assert_fails('wprevious! .', 'E502:')
+
+  %bwipe!
+  call delete('X1')
+  call delete('X2')
+  call delete('X3')
+  call delete('X4')
+endfunc
diff --git a/src/version.c b/src/version.c
index 567e870..1451697 100644
--- a/src/version.c
+++ b/src/version.c
@@ -784,6 +784,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    926,
+/**/
     925,
 /**/
     924,