channel: recognized nvim-style errors

test/functional/api/server_requests_spec.lua

@@ -148,5 +148,11 @@ describe('server -> client', function()
       -- Call get_line_slice(buf, range [0,0], includes start, includes end)
       eq({'SOME TEXT'}, eval("rpcrequest(vim, 'buffer_get_line_slice', "..buf..", 0, 0, 1, 1)"))
     end)
+
+    it('returns an error if the request failed', function()
+      local status, err = pcall(eval, "rpcrequest(vim, 'does-not-exist')")
+      eq(false, status)
+      eq(true, string.match(err, ': (.*)') == 'Failed to evaluate expression')
+    end)
   end)
 end)