A fictional media platform needs a dependency library for its processing jobs. Build cycle detection, a deterministic release order, parallel finish times, an order-uniqueness check, critical-chain counts and termination analysis. The clients in the fixtures supply different graphs. Deliver one file with all six tested functions. Explain which questions require a directed acyclic graph and which must still return useful evidence when cycles exist.
Build a small source file that another engineer can reuse. Each step adds one function with its own contract and tests. Keep earlier functions while you add the next one.
The final file is your deliverable.
Check each helper as you go. An earlier function can still contain a defect after a new helper passes, so review the combined file before handing it over.