test: fix HTTP address reload check

Connecting to 0.0.0.0 is environment-dependent. On Linux it may reach
a listener on 127.0.0.1, so the test can fail even when the server is
recreated with the expected address.

This patch verifies the host and port kept by roles.httpd after reload.
The existing HTTP request checks that the recreated server is running.

Closes #228

Author: mandesero

test/integration/httpd_role_test.lua

@@ -170,7 +170,16 @@ g.test_change_server_addr_on_the_run = function(cg)
     local _, err = cg.server:eval("require('config'):reload()")
     t.assert_not(err)
 
-    t.assert_not(helpers.tcp_connection_exists('0.0.0.0', 13001))
+    t.assert_equals(cg.server:eval([[
+        local httpd = require('roles.httpd').get_server('additional')
+        return {
+            host = httpd.host,
+            port = httpd.port,
+        }
+    ]]), {
+        host = 'localhost',
+        port = 13001,
+    })
     resp = http_client:get('http://localhost:13001/ping')
     t.assert_equals(resp.status, 200, 'response not 200')
     t.assert_equals(resp.body, 'pong')