First stage of the interview was +/- fine - it is a screening with engineering manager. But it was weird he wanted to know some technical details. I had an impression he tries to evaluate my skills while not being a programmer by himself. Second stage - technical task. It required from me to implement CSV parsing using their DSL and parse 3 csv files from different crypto coin services. The thing is - there is 0 docs of their DSL. Second - 0 docs regarding what csv content I am actually looking at. If you never dealt with financial transactions import - it will be even harder to understand that. Nevertheless I continued. First step was to reverse-engineer that "super awesome" DSL and understand how it works, implement an importer for the first csv file, implement tests(there is onyl one way to write tests there as well). The thing is tests there don't show whether your solution is right or wrong - it only shows whether the API call to their private API to import that CSV was successful. Thus, you never know whether you was looking by guessing how to import that or another csv. A little inside regarding csv files you need to parse - last file contains transactions you need to group by the transaction ID(there is a related DSL method). At least that's what you may think from the start. And that's what they would expect from you. But if you would look closer - two rows with same transaction ID(at the very top) have different transaction amount which basically means the content requires more investigation - e.g. by writing to the support of the related crypto service and asking them to clarify, but, of course, you won't be able to finish this task in 5 hours xD After I submitted my work to HR I only received a rejection email with the general description about how wrong I was when implementing their test task. No chance to discuss the solution even and that ambiguity with grouping of transactions.