Off by one, in disguise
Why it matters When only one case looks broken, it is tempting to treat that case as special. Usually it is just the case somebody looked at.
An admin page shows a CSV export one page at a time. The first row of the CSV is the header. A support ticket says page 1 is missing a person:
rows = [["name", "city"], ["Ana", "Leeds"], ["Ben", "York"], ["Cai", "Bath"], ...]
get_page(rows, 1, 3)
# expected [["Ana", "Leeds"], ["Ben", "York"], ["Cai", "Bath"]]
# got [["Ana", "Leeds"], ["Ben", "York"]]The header row makes page 1 look like the odd one out. Before you agree, work out what page 2 returns.
Fix get_page(rows, page, size). rows[0] is a header row and is never returned; pages start at 1 and hold size data rows each (the last may hold fewer, and pages past the end are empty). The hidden tests check every page of 80 tables with different sizes, and that reading the pages in order gives every data row exactly once.
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