[tarantool-patches] Re: [PATCH 1/2] Add test on error during reconfigure

[Alex Khatskevich <avkhatskevich@tarantool.org>]

>> +-- Error during reconfigure process.
>> +_ = vshard.router.route(1):callro('echo', {'some_data'})
>
> 1. Why do you need this call here? It does nor outputs
> nothing.
Because next call checks a raised error.
This line ensures that an error ocured only after
`vshard.router.internal.errinj.ERRINJ_CFG = true`
just by not failing.

I did it to prevent test.result flooding.
>> +---
>> +...
>> +vshard.router.internal.errinj.ERRINJ_CFG = true
>> +---
>> +...
>> +old_internal = table.copy(vshard.router.internal)
>> +---
>> +...
>> +_, err = pcall(vshard.router.cfg, cfg)
>> +---
> 2. Same. Maybe this call should output something? This
> test would not fail if callro failed. Call/ro/rw do not
> throw exceptions but return a pair: result and error if
> occurred.
The error I test here returns as a raised exception.
> 3. Same. Here and at the end of the test.
Same
>> diff --git a/vshard/router/init.lua b/vshard/router/init.lua
>> index 21093e5..1dee80c 100644
>> --- a/vshard/router/init.lua
>> +++ b/vshard/router/init.lua
>> @@ -473,6 +474,12 @@ local function router_cfg(cfg)
>>       end
>>       box.cfg(cfg)
>>       log.info("Box has been configured")
>> +    -- It is considered that all possible errors during cfg
>> +    -- process occur only before this place.
>> +    -- This check should be placed as late as possible.
>> +    if M.errinj.ERRINJ_CFG then
>> +        error('Error injection: cfg')
>> +    end
>
> 4. I think, you should place this injection before box.cfg.
> All the cfg() code relies on the fact, that box.cfg is atomic.
> And if box.cfg is ok, then storage/router.cfg finish with
> no errors. An error is possible only before box.cfg and in
> box.cfg. You may think box.cfg like commit, and code before
> box.cfg like prepare.
In this case it does not matter, because it is just an errinj. However I 
wanted to show here,
that error should be raised as late as possible. It can help in the 
future, if someone adds a code after `box.cfg`. I prefer errnj to be 
here and will move it only if you insist.