refactor: organize backend by business responsibility

2026-09-13 13:52:57 +03:00
parent 7fde3ece6e
commit 8ba005346d
145 changed files with 3027 additions and 2346 deletions
@@ -0,0 +1,153 @@
+import {
+  bankBalance,
+  bankSummary,
+  isCalendarDate,
+  moscowToday,
+} from './bank-card.calculations';
+
+describe('bank card calculations', () => {
+  it('uses Moscow midnight for today and the current month', () => {
+    expect(moscowToday(new Date('2026-08-31T20:59:59.999Z'))).toBe(
+      '2026-08-31',
+    );
+    expect(moscowToday(new Date('2026-08-31T21:00:00.000Z'))).toBe(
+      '2026-09-01',
+    );
+  });
+
+  it.each([
+    '0001-01-01',
+    '9999-12-31',
+    '2024-02-29',
+    '2000-02-29',
+    '2026-09-12',
+  ])('accepts calendar date %s', (value) => {
+    expect(isCalendarDate(value)).toBe(true);
+  });
+
+  it.each([
+    '0000-01-01',
+    '10000-01-01',
+    '2026-02-29',
+    '1900-02-29',
+    '2026-04-31',
+    '2026-00-01',
+    '2026-13-01',
+    '2026-01-00',
+    '2026-01-32',
+    '2026-1-01',
+    '2026-09-12\n',
+    '2026-09-12T00:00:00Z',
+    '',
+  ])('rejects invalid calendar date %s', (value) => {
+    expect(isCalendarDate(value)).toBe(false);
+  });
+
+  it('folds expenses, topups, refunds and both transfer sides exactly', () => {
+    const operations = [
+      { kind: 'expense', cardId: 'a', targetCardId: null, amountKopecks: 10n },
+      { kind: 'expense', cardId: 'a', targetCardId: null, amountKopecks: 20n },
+      { kind: 'topup', cardId: 'a', targetCardId: null, amountKopecks: 15n },
+      { kind: 'refund', cardId: 'a', targetCardId: null, amountKopecks: 5n },
+      { kind: 'transfer', cardId: 'a', targetCardId: 'b', amountKopecks: 120n },
+      { kind: 'expense', cardId: 'c', targetCardId: null, amountKopecks: 300n },
+    ];
+    expect(bankBalance('a', 100n, operations.slice(0, 2))).toBe(70n);
+    expect(bankBalance('a', 100n, operations)).toBe(-30n);
+    expect(bankBalance('b', 0n, operations)).toBe(120n);
+    expect(bankBalance('unused', -1n, operations)).toBe(-1n);
+  });
+
+  it('does not bound computed balances by the storage range', () => {
+    expect(
+      bankBalance('a', 2n ** 63n - 1n, [
+        { kind: 'topup', cardId: 'a', targetCardId: null, amountKopecks: 1n },
+      ]),
+    ).toBe(2n ** 63n);
+    expect(
+      bankBalance('a', -(2n ** 63n), [
+        { kind: 'expense', cardId: 'a', targetCardId: null, amountKopecks: 1n },
+      ]),
+    ).toBe(-(2n ** 63n) - 1n);
+  });
+
+  it('counts refunds in their own month and inherited category, excluding transfers and topups', () => {
+    const operations = [
+      {
+        kind: 'expense',
+        date: '2026-08-31',
+        categoryId: 'food',
+        amountKopecks: 1000n,
+      },
+      {
+        kind: 'refund',
+        date: '2026-09-01',
+        categoryId: 'food',
+        amountKopecks: 500n,
+      },
+      {
+        kind: 'expense',
+        date: '2026-09-30',
+        categoryId: 'food',
+        amountKopecks: 100n,
+      },
+      {
+        kind: 'expense',
+        date: '2026-09-03',
+        categoryId: 'travel',
+        amountKopecks: 20n,
+      },
+      {
+        kind: 'transfer',
+        date: '2026-09-03',
+        categoryId: null,
+        amountKopecks: 2000n,
+      },
+      {
+        kind: 'topup',
+        date: '2026-09-03',
+        categoryId: null,
+        amountKopecks: 3000n,
+      },
+      {
+        kind: 'expense',
+        date: '2026-10-01',
+        categoryId: 'travel',
+        amountKopecks: 5000n,
+      },
+    ];
+    expect(bankSummary('2026-09', operations)).toEqual({
+      expenses: 120n,
+      refunds: 500n,
+      net: -380n,
+      categories: [
+        { categoryId: 'food', expenses: 100n, refunds: 500n, net: -400n },
+        { categoryId: 'travel', expenses: 20n, refunds: 0n, net: 20n },
+      ],
+    });
+    expect(bankSummary('2026-07', operations)).toEqual({
+      expenses: 0n,
+      refunds: 0n,
+      net: 0n,
+      categories: [],
+    });
+  });
+
+  it('keeps summary sums beyond signed 64-bit exact', () => {
+    const operation = {
+      kind: 'expense',
+      date: '2026-09-01',
+      categoryId: 'food',
+      amountKopecks: 2n ** 63n - 1n,
+    };
+    const total = 2n * (2n ** 63n - 1n);
+    expect(bankSummary('2026-09', [operation, operation])).toEqual({
+      expenses: total,
+      refunds: 0n,
+      net: total,
+      categories: [
+        { categoryId: 'food', expenses: total, refunds: 0n, net: total },
+      ],
+    });
+  });
+});