Added unit tests, documentation and function descriptions across the board. Increased cyclop complexity threshold to 15 which is a bit more sane than 10 and excluded _test.go files from linters.

internal/fetcher/worker_sleeper.go

@@ -30,6 +30,9 @@ func runSleeper(
 	return w.Run(ctx, since)
 }
 
+// sleep simulates work taking duration, returning early with ctx.Err() if ctx
+// is cancelled. With blockShutdown, the work itself ignores ctx (as a
+// non-cooperative call would) and only the wait for it stops.
 func sleep(
 	ctx context.Context, blockShutdown bool, duration time.Duration,
 ) error {