The run's line coverage: one entry per source file, plus the totals across all of them.
const coverage: CoverageSummary = { files: [], coveredLines: 0, coverableLines: 0, percent: 0 }; coverage.files.length; // 0 — nothing coverable was found
files: FileCoverageSummary[]
One entry per non-test source file the bundle mapped back to.