Build Read Models with Subscription Checkpoint + Testing concurrency!
In this video we discuss how to build a read model using subscription checkpoint. But besides that we discuss how you can test those read model builders simulating async world. The scenario that we discuss and test (besides others that you can find in the repo) is the one in which the job "slows down" a little and the other one finishes before it. Then, the result is overwritten.
We also discuss how you can prevent yourself from that scenario. We're using #ruby #rubyonrails and #RailsEventStore to cover that, but this knowledge is universal.