That still doesn't guarantee that a consecutive read is gonna get the last state.
Do you have other information about the refresh flag because their documentation clearly states that forcing a refresh is applied to primary and replica shards meaning that it will be available for query directly after the call to refresh is made.
However, this was back in ~2015 and Elasticsearch 1.3 or something like this, which is of course a now-ancient version. Perhaps things are different now.
edit: Perhaps we were using the refresh command and not the refresh flag. It was a few years ago and I don't have access to the code any more, and my memory may be failing here. If the refresh flag works as advertised (enforces an index update and guarantees a consistent view of the data for the next query, which the command did not seem to) then that of course solves my initial problem W.R.T. writing tests.
I've run countless integration tests with ES and never seen something fail due to refresh not working as advertised. If you have, what version of ES was it? Can you give some sample code that sporadically exhibits the problem?
The refresh command can also be called (which is what you're doing) but this is a different operation and just triggers the index build with no guarantees that it finishes or is consistent with any particular data mutation.
Did you read the previously posted documentation for the refresh flag?