Module 4 of 8
Build sprint
Automate the selected sequence.
Build the happy path first and get it working end to end with real data, even if it handles nothing unusual. A working narrow path tells you more about your design than a week of further planning.
Log everything as you go — every run, every input, every output. You will need the log the first time somebody asks why a particular item was handled the way it was, and building logging in afterwards is far harder than building it in now.
Takeaway
Get the happy path working end to end on real data first, and log every run from the beginning.