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no-coverage-pragma (BTTEST004)

Added in 0.14.0 · Preview · Off by default (warning)

Family: testing · Standard: CES-66 · Languages: python

This rule is unstable and in preview. It runs only with preview = true, and only when it is selected.

Directive

A Python comment # pragma: no cover, the marker that coverage.py leaves out of its report, is reported, in any case and spacing that coverage.py reads (#pragma:no cover, # PRAGMA: NO COVER). A warning by default. With botica lint --diff, only a pragma on a line that the change adds is reported.

Why

A pragma raises the percentage of coverage and tests nothing: the line it marks has no test, and a bug on it stays unseen. The gap is a missing test, dead code, or a seam to refactor, and each has a fix that is not the pragma.

Do

def test_an_empty_order_costs_nothing():
    assert total(Order(items=[])) == 0

if __name__ == "__main__":  # pragma: no cover  # noqa: BTTEST004 -- a script
    main()

Don't

def total(order):
    if not order.items:  # pragma: no cover
        return 0
    return sum(item.price for item in order.items)

Suppression

# botica: ignore[no-coverage-pragma] -- <reason> or # noqa: BTTEST004 -- <reason> on the line of the pragma, for code that cannot run under test: the block of if __name__ == "__main__":, a branch for another platform, or generated code. A file of generated code goes in the extend-ignores of [rules.no-coverage-pragma].

Discussion