[Tarantool-patches] [PATCH test-run 1/1] Wait_upstream/downstream should be ready to nil info

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

Wait_upstream/downstream are helper functions of a
test-run object. They are used to wait until a certain
state of upstream/downstream is reached such as error
message, replication status.

They take these attributes from
box.info.replication[id].upstream/downstream, which
sometimes can be nil, and it led to an error.

Now these waiters check upstream/downstream for nil.

The bug was discovered in Tarantool in
replication/show_error_on_disconnect test:
https://github.com/tarantool/tarantool/issues/4563.

It appeared, because after my patch reconfiguration of
replication with 0 quorum always returns immediately.
And right after the reconfiguration the
upstream/downstream may still do not exist. This is
why test_run:wait_upstream/downstream might fail like
this:

    [002]  test_run:wait_upstream(other_id, {status = 'stopped', message_re = 'Missing'})
    [002]  ---
    [002] -- true
    [002] +- error: '.../Workspaces/gitlab/test/var/002_replication/test_run.lua:250: attempt
    [002] +    to index local ''info'' (a nil value)'
---
Branch: https://github.com/tarantool/test-run/tree/gerold103/gh-tarantool-4563-box.info.repl.upstream-nil
Issue: https://github.com/tarantool/tarantool/issues/4563

 test_run.lua | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/test_run.lua b/test_run.lua
index 8f13491..09d53af 100644
--- a/test_run.lua
+++ b/test_run.lua
@@ -234,10 +234,15 @@ local function log_box_info_replication_cond(id, field, ok, info, opts)
         status = opts.status,
         message_re = opts.message_re,
     })
-    local got = json.encode({
-        status = info.status,
-        message = info.message,
-    })
+    local got
+    if info then
+        got = json.encode({
+            status = info.status,
+            message = info.message,
+        })
+    else
+        got = json.encode('info is nil')
+    end
     log.info('wait_%s(%d, ...); exp = %s; got = %s; result = %s', field, id,
         exp, got, tostring(ok))
 end
@@ -247,7 +252,7 @@ local function gen_box_info_replication_cond(id, field, opts)
         local info = box.info.replication[id][field]
         local ok = true
         if opts.status ~= nil then
-            ok = ok and info.status == opts.status
+            ok = ok and info and info.status == opts.status
         end
         if opts.message_re ~= nil then
             -- regex match
-- 
2.21.0 (Apple Git-122)