testsAndMisc-archive/billsplit

BillSplit

Flutter app (mobile + desktop) for splitting shop receipts between people — including the drinkers vs non-drinkers case — with Biedronka e-paragon import and .xlsx export.

Features

• People roster with a per-person drinks alcohol toggle, plus arbitrary groups (tags) like "meat eaters".
• Receipts: import a Polish fiscal e-receipt JSON (e-paragon, JPK_KASA_PARAGON_v2-0 — the file the Biedronka app exports; the embedded JWS payload is decoded, signature not verified) or build one manually. Multiple receipts persist locally (state.json in app documents).
• Per-item assignment: each item is split among Everyone / Drinkers / Non-drinkers / a group / hand-picked people. Alcohol is auto-detected on import (wódka/piwo/wino/… keywords) and defaults to drinkers only; deposits (kaucja) become their own line split among everyone. Category and assignment are always editable — the keyword detection is a default, not a decision.
• Grosz-exact math: every item's shares sum to exactly the item total (largest-remainder distribution), so per-person totals reconcile with the receipt to the grosz — no floating point drift.
• Totals view: per person, with alcohol / rest breakdown, unassigned-item warnings, and a reconciliation check against the paid amount.
• Export .xlsx: one row per item with a 1/0 person matrix plus a summary — same layout as the hand-made spreadsheet this app grew out of. Matrix and summary are exported values (the app is the calculator); column totals are live SUM formulas.

Running

android/ is the only platform runner folder the repo tracks. Generate the others locally for whatever you want to run on:

cd billsplit
flutter create . --platforms=linux,windows,macos,ios
flutter pub get
flutter run          # picks a connected device / desktop

Those four directories are gitignored, so a regenerated runner stays local instead of being committed back. CI never builds them: billsplit-ci.yml runs flutter analyze and flutter test only.

Tested with Flutter 3.44.8 / Dart 3.10.

Tests

flutter test

Covers: parsing the real sample receipt in test/fixtures/ (49 items + deposit, totals 590.55 + 7.00 = 597.55 zł), split invariants incl. a 500-case fuzz of the remainder distribution, assignment-mode resolution, and xlsx generation (the test writes build/test_export.xlsx for external inspection).

Design notes / edge cases

• Money is int grosze end to end; formatting happens only at the UI edge.
• An item resolving to zero people (e.g. "non-drinkers" on an all-drinker receipt) is excluded from totals and loudly flagged, never silently dropped into someone's bill.
• Deleting a person prunes them from groups, receipt participants and custom assignments; deleting a group falls back affected items to Everyone.
• Assignment modes are stored symbolically (not as materialized ID sets), so adding a person later automatically includes them in Everyone items. Touching a person checkbox materializes the current set and switches the item to custom.
• paidTotalGr (what the card was charged) is kept separately from the item sum; a mismatch shows red in Totals instead of being "fixed" silently.

Quality gates (enforced in CI)

• dart format --set-exit-if-changed . — formatting is canonical
• flutter analyze --fatal-infos — very_good_analysis + strict-casts, strict-inference, strict-raw-types; any info fails the build
• flutter test --coverage + tool/coverage_check.py — 100% line coverage of lib/ is mandatory; the gate also fails if a lib file is never executed by any test