[PATCH] test: fix hardcoded port in box/net.box.test.lua

[Alexander Turenko]

It allows to run the test many times in parallel to investigate flaky
test failures and decreases probability that the test fails, because
this port was already used by, say, some other test.
---

no issue
https://github.com/tarantool/tarantool/tree/Totktonada/fix-hardcoded-port-in-net.box.test.lua

The patch was created to reproduce the issue #3851.

https://github.com/tarantool/tarantool/issues/3851

The branch is based on top of 2.1.

I think it also good to cherry-pick test fixes to 1.10, but it is up to
maintainers.

 test/box/net.box.result   | 7 ++++---
 test/box/net.box.test.lua | 7 ++++---
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/test/box/net.box.result b/test/box/net.box.result
index 4f6979d5b..faae5e9a5 100644
--- a/test/box/net.box.result
+++ b/test/box/net.box.result
@@ -1880,7 +1880,7 @@ greeting =
 socket = require('socket');
 ---
 ...
-srv = socket.tcp_server('localhost', 3392, {
+srv = socket.tcp_server('localhost', 0, {
     handler = function(fd)
         local fiber = require('fiber')
         fiber.sleep(0.1)
@@ -1890,7 +1890,8 @@ srv = socket.tcp_server('localhost', 3392, {
 ---
 ...
 -- we must get timeout
-nb = net.new('localhost:3392', {
+port = srv:name().port
+nb = net.new('localhost:' .. port, {
     wait_connected = true, console = true,
     connect_timeout = 0.01
 });
@@ -1904,7 +1905,7 @@ nb:close();
 ---
 ...
 -- we must get peer closed
-nb = net.new('localhost:3392', {
+nb = net.new('localhost:' .. port, {
     wait_connected = true, console = true,
     connect_timeout = 0.2
 });
diff --git a/test/box/net.box.test.lua b/test/box/net.box.test.lua
index 5201e01a6..dd6c2fd94 100644
--- a/test/box/net.box.test.lua
+++ b/test/box/net.box.test.lua
@@ -754,22 +754,23 @@ greeting =
 "Tarantool 1.7.3 (Lua console)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n" ..
 "type 'help' for interactive help~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n";
 socket = require('socket');
-srv = socket.tcp_server('localhost', 3392, {
+srv = socket.tcp_server('localhost', 0, {
     handler = function(fd)
         local fiber = require('fiber')
         fiber.sleep(0.1)
         fd:write(greeting)
     end
 });
+port = srv:name().port
 -- we must get timeout
-nb = net.new('localhost:3392', {
+nb = net.new('localhost:' .. port, {
     wait_connected = true, console = true,
     connect_timeout = 0.01
 });
 nb.error:find('timed out') ~= nil;
 nb:close();
 -- we must get peer closed
-nb = net.new('localhost:3392', {
+nb = net.new('localhost:' .. port, {
     wait_connected = true, console = true,
     connect_timeout = 0.2
 });
-- 
2.19.2