How HandyGrid tests browser-local tools

The spreadsheet engine parses CSV into a typed row model before cleaning, comparing or writing an XLSX workbook. Tests cover commas inside quoted fields, escaped quotes, multiline cells, empty rows, duplicates and a round trip from CSV rows to an Excel workbook and back to readable data.

Browser tests exercise real file selection, multiple worksheets and downloads. Each input is limited to 4 MB and remains in local browser memory. Formulas, macros, external links and embedded code are not executed. Formatting and advanced workbook features may not survive a plain CSV conversion because CSV stores values rather than workbook presentation.

Evidence: src/lib/spreadsheet.test.ts and e2e/spreadsheet-trade-grid.spec.ts. Try the CSV Cleaner, CSV to Excel or Excel to CSV.

The mortgage calculator uses the standard fixed-rate annuity formula for monthly payments and a separate zero-interest branch. Month-by- month balances apply interest before principal reduction; the final payment is bounded by the remaining balance. Tests check a known 200,000 principal example, zero-rate loans, a six-month boundary, invalid values, the 500,000,000 principal cap, extra payments, refinance comparisons and a balance that reaches zero.

Currency selection changes display formatting, not the mathematics. Results are estimates rounded for presentation and exclude taxes, insurance, lender fees, penalties and future rate changes unless an input explicitly models them.

Evidence: src/lib/calculations.test.ts, src/lib/mortgage-analysis.test.ts, src/lib/financial-charts.test.ts and e2e/financial-charts.spec.ts. Open the Mortgage Calculator.

PDF files are read as browser file bytes and processed by client-side components. End-to-end tests load representative PDFs, inspect page counts, exercise page editing and export, and verify that a downloaded flattened PDF can be opened. The application has no document upload endpoint, account, cloud document store or server-side PDF processor.

Large or unusually complex documents can exceed browser memory. Office imports create simplified readable PDFs and do not promise exact Word, PowerPoint or Excel layout fidelity. Scanned text is not silently represented as reliable OCR output.

Evidence: e2e/combined-pdf.spec.ts and the client modules under src/components/pdf. Review the local PDF editor and PDF actions.

The IPv4 subnet calculator validates four decimal octets and a CIDR prefix before applying a 32-bit mask. It derives network and broadcast addresses from bitwise boundaries and reports the usable range and address count according to the displayed assumptions. Tests include the host address 192.168.1.42/24 and reject malformed addresses such as 999.1.1.1.

The result describes address arithmetic, not reachability, routing, firewall policy or a live network scan. Point-to-point and host-route conventions for /31 and /32 networks must be interpreted for the actual equipment and protocol in use.

Evidence: src/lib/utility-calculations.test.ts and e2e/core.spec.ts. Use the IPv4 Subnet Calculator.

Production releases require formatting, linting, strict TypeScript, unit tests, Chromium end-to-end tests, a static production build, translation and monetization checks, SEO-output validation, performance budgets and hosting-header checks. These controls reduce known regressions but cannot prove that every possible input or device behaves perfectly.

Possible errors can be reported through the contact pagewith the page URL, inputs, observed result, expected result and a supporting source. See About HandyGrid for publication responsibility and review boundaries.