patch 8.0.0479: remote_peek() is not tested

Problem:    remote_peek() is not tested.
Solution:   Add a test.

src/testdir/runtest.vim

@@ -247,6 +247,8 @@ for s:test in sort(s:tests)
   call RunTheTest(s:test)
 
   if len(v:errors) > 0 && index(s:flaky, s:test) >= 0
+    call add(s:messages, 'Found errors in ' . s:test . ':')
+    call extend(s:messages, v:errors)
     call add(s:messages, 'Flaky test failed, running it again')
     let v:errors = []
     call RunTheTest(s:test)

src/testdir/test_clientserver.vim

@@ -81,6 +81,27 @@ func Test_client_server()
   call assert_equal('got it', remote_read(g:myserverid))
   let s:where = 16
 
+  call remote_send(name, ":call server2client(expand('<client>'), 'another')\<CR>", 'g:myserverid')
+  let s:where = 151
+  let peek_result = 'nothing'
+  let r = remote_peek(g:myserverid, 'peek_result')
+  let s:where = 161
+  " unpredictable whether the result is already avaialble.
+  if r > 0
+    call assert_equal('another', peek_result)
+  elseif r == 0
+    call assert_equal('nothing', peek_result)
+  else
+    call assert_report('remote_peek() failed')
+  endif
+  let g:peek_result = 'empty'
+  call WaitFor('remote_peek(g:myserverid, "g:peek_result") > 0')
+  let s:where = 171
+  call assert_equal('another', g:peek_result)
+  let s:where = 181
+  call assert_equal('another', remote_read(g:myserverid))
+  let s:where = 191
+
   call remote_send(name, ":qa!\<CR>")
   let s:where = 17
   call WaitFor('job_status(g:job) == "dead"')

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    479,
 /**/
     478,
 /**/