Feat: tax-saving 서버 액션에 대한 테스트 코드 작성

__tests__/services/tax-saving.test.ts

@@ -0,0 +1,172 @@
+import { getServerSession } from 'next-auth';
+import { taxSaving } from '@/app/actions/tax-saving';
+import { prisma } from '@/lib/prisma';
+
+jest.mock('next-auth', () => ({ getServerSession: jest.fn() }));
+jest.mock('@/lib/prisma', () => ({
+  prisma: {
+    iSAAccount: { findUnique: jest.fn() },
+    generalTransaction: { aggregate: jest.fn() },
+    eTFTransaction: { aggregate: jest.fn() },
+    eTFHolding: { findMany: jest.fn() },
+    etfDailyTrading: { findFirst: jest.fn() },
+  },
+}));
+
+beforeAll(() => {
+  jest
+    .spyOn(Date, 'now')
+    .mockReturnValue(new Date('2025-06-15T00:00:00Z').getTime());
+});
+afterAll(() => jest.restoreAllMocks());
+
+describe('taxSaving – 두 시나리오 (usedLimit capped but isaTax on full overflow)', () => {
+  (getServerSession as jest.Mock).mockResolvedValue({ user: { id: '1' } });
+
+  it('1. 일반형 / grossDiv=20만원, estDiv=10만원, gain=500만원', async () => {
+    // 셋업
+    (prisma.iSAAccount.findUnique as jest.Mock).mockResolvedValue({
+      id: 1,
+      accountType: '일반형',
+    });
+    // grossDiv
+    (prisma.generalTransaction.aggregate as jest.Mock)
+      .mockResolvedValueOnce({ _sum: { price: { toNumber: () => 200_000 } } })
+      .mockResolvedValueOnce({ _sum: { price: { toNumber: () => 0 } } });
+    // estDiv = 10M*2%*6/12 =100k
+    (prisma.eTFHolding.findMany as jest.Mock).mockResolvedValue([
+      {
+        etfId: 1,
+        avgCost: { toNumber: () => 10_000_000 },
+        quantity: { toNumber: () => 1 },
+        etf: { idxMarketType: '국내' },
+      },
+    ]);
+    (prisma.etfDailyTrading.findFirst as jest.Mock).mockResolvedValue({
+      tddClosePrice: { toNumber: () => 10_000_000 },
+    });
+    // 해외 gain
+    (prisma.eTFTransaction.aggregate as jest.Mock)
+      .mockResolvedValueOnce({ _sum: { price: { toNumber: () => 5_000_000 } } })
+      .mockResolvedValueOnce({ _sum: { price: { toNumber: () => 0 } } });
+
+    const res = await taxSaving();
+
+    // 계산
+    const grossDiv = 200_000;
+    const estDiv = 100_000;
+    const gain = 5_000_000;
+    const sum = grossDiv + estDiv + gain; // 5_300_000
+    const tax = sum * 0.154; // 816200
+    const limit = 2_000_000;
+    const used = limit; // capped
+    const remaining = 0;
+    const isaBase = sum - limit; // 3_300_000
+    const isaTax = isaBase * 0.099; // 326700
+    const saved = tax - isaTax; // 489500
+
+    expect(res.limit).toBe(limit);
+    expect(res.totalTaxableGeneral).toBe(sum);
+    expect(res.generalAccountTax).toBeCloseTo(tax, 2);
+    expect(res.usedLimit).toBe(used);
+    expect(res.remainingTaxFreeLimit).toBe(remaining);
+    expect(res.isaTax).toBeCloseTo(isaTax, 2);
+    expect(res.savedTax).toBeCloseTo(saved, 2);
+  });
+
+  it('2. 서민형 / grossDiv=10만원, estDiv=20만원, gain=600만원', async () => {
+    (prisma.iSAAccount.findUnique as jest.Mock).mockResolvedValue({
+      id: 2,
+      accountType: '서민형',
+    });
+    (prisma.generalTransaction.aggregate as jest.Mock)
+      .mockResolvedValueOnce({ _sum: { price: { toNumber: () => 100_000 } } })
+      .mockResolvedValueOnce({ _sum: { price: { toNumber: () => 0 } } });
+    (prisma.eTFHolding.findMany as jest.Mock).mockResolvedValue([
+      {
+        etfId: 1,
+        avgCost: { toNumber: () => 20_000_000 },
+        quantity: { toNumber: () => 1 },
+        etf: { idxMarketType: '해외' },
+      },
+    ]);
+    (prisma.etfDailyTrading.findFirst as jest.Mock).mockResolvedValue({
+      tddClosePrice: { toNumber: () => 20_000_000 },
+    });
+    (prisma.eTFTransaction.aggregate as jest.Mock)
+      .mockResolvedValueOnce({ _sum: { price: { toNumber: () => 6_000_000 } } })
+      .mockResolvedValueOnce({ _sum: { price: { toNumber: () => 0 } } });
+
+    const res = await taxSaving();
+
+    const grossDiv = 100_000;
+    const estDiv = 200_000;
+    const gain = 6_000_000;
+    const sum = grossDiv + estDiv + gain; // 6_300_000
+    const tax = sum * 0.154; // 970200
+    const limit = 4_000_000;
+    const used = limit; // capped
+    const remaining = 0;
+    const isaBase = sum - limit; // 2_300_000
+    const isaTax = isaBase * 0.099; // 227700
+    const saved = tax - isaTax; // 742500
+
+    expect(res.limit).toBe(limit);
+    expect(res.totalTaxableGeneral).toBe(sum);
+    expect(res.generalAccountTax).toBeCloseTo(tax, 2);
+    expect(res.usedLimit).toBe(used);
+    expect(res.remainingTaxFreeLimit).toBe(remaining);
+    expect(res.isaTax).toBeCloseTo(isaTax, 2);
+    expect(res.savedTax).toBeCloseTo(saved, 2);
+  });
+
+  it('3. 일반형 / grossDiv=50만원, estDiv=50만원, gain=20만원 (no cap)', async () => {
+    // 계좌 타입
+    (prisma.iSAAccount.findUnique as jest.Mock).mockResolvedValue({
+      id: 3,
+      accountType: '일반형',
+    });
+    // grossDiv = 500k
+    (prisma.generalTransaction.aggregate as jest.Mock)
+      .mockResolvedValueOnce({ _sum: { price: { toNumber: () => 500_000 } } })
+      .mockResolvedValueOnce({ _sum: { price: { toNumber: () => 0 } } });
+    // estDiv = 5M*2%*6/12 = 50k
+    (prisma.eTFHolding.findMany as jest.Mock).mockResolvedValue([
+      {
+        etfId: 1,
+        avgCost: { toNumber: () => 5_000_000 },
+        quantity: { toNumber: () => 1 },
+        etf: { idxMarketType: '국내' },
+      },
+    ]);
+    (prisma.etfDailyTrading.findFirst as jest.Mock).mockResolvedValue({
+      tddClosePrice: { toNumber: () => 5_000_000 },
+    });
+    // realizedOver = 200k
+    (prisma.eTFTransaction.aggregate as jest.Mock)
+      .mockResolvedValueOnce({ _sum: { price: { toNumber: () => 200_000 } } })
+      .mockResolvedValueOnce({ _sum: { price: { toNumber: () => 0 } } });
+
+    const res = await taxSaving();
+
+    // 올바른 계산
+    const grossDiv = 500_000;
+    const estDiv = 50_000;
+    const gain = 200_000;
+    const sum = grossDiv + estDiv + gain; // 750_000
+    const tax = sum * 0.154; // 115,500
+    const limit = 2_000_000;
+    const used = sum; // 750_000
+    const remaining = limit - used; // 1_250_000
+    const isaTax = 0; // 한도 내 전부 비과세
+    const saved = tax; // 115,500
+
+    expect(res.limit).toBe(limit);
+    expect(res.totalTaxableGeneral).toBe(sum);
+    expect(res.generalAccountTax).toBeCloseTo(tax, 2);
+    expect(res.usedLimit).toBe(used);
+    expect(res.remainingTaxFreeLimit).toBe(remaining);
+    expect(res.isaTax).toBe(isaTax);
+    expect(res.savedTax).toBeCloseTo(saved, 2);
+  });
+});

app/(routes)/isa/page.tsx

@@ -20,6 +20,7 @@ const ISAPage = async () => {
   }
 
   const taxData = await taxSaving();
+  console.log(taxData);
   const monthlyReturnsData: MonthlyReturnsSummary = {
     ...(await getMonthlyReturns('6')),
     monthlyEvaluatedAmounts: [],

app/actions/get-trasactions.tsx

@@ -57,7 +57,7 @@ export const getTransactions = async (): Promise<CalendarData> => {
     label: string;
   };
 
-  const normalized: TxCommon[] = [
+  const allTxs: TxCommon[] = [
     ...generalTxs.map((g) => ({
       id: g.id.toString(),
       rawType: g.transactionType,
@@ -74,6 +74,11 @@ export const getTransactions = async (): Promise<CalendarData> => {
     })),
   ];
 
+  const now = new Date();
+  const pastAndTodayTxs = allTxs.filter(
+    (tx) => tx.at.getTime() <= now.getTime()
+  );
+
   const typeMap: Record<string, CalendarTx['type']> = {
     BUY: '매수',
     SELL: '매도',
@@ -85,8 +90,8 @@ export const getTransactions = async (): Promise<CalendarData> => {
   };
 
   const transactionData: Record<string, CalendarTx[]> = {};
-  normalized.forEach((tx) => {
-    const key = tx.at.toISOString().slice(0, 10);
+  pastAndTodayTxs.forEach((tx) => {
+    const key = tx.at.toISOString().slice(0, 10); // YYYY-MM-DD
     if (!transactionData[key]) transactionData[key] = [];
     transactionData[key].push({
       title: tx.label,

app/actions/tax-saving.tsx

@@ -1,5 +1,6 @@
 /**
- * ISA 절세 계산기 ― ETF 배당 비과세 + 잔여 한도 계산(배당 전부 반영)
+ * ISA 절세 계산기 ― ETF 배당 비과세 + 잔여 한도 계산
+ * “지금 전부 매도해 현금화(만기 가정)” 시, ISA vs 일반계좌 세금을 비교합니다.
  */
 'use server';
 
@@ -8,11 +9,11 @@ import { authOptions } from '@/lib/auth-options';
 import { prisma } from '@/lib/prisma';
 
 const TAX_INT_DIV = 0.154; // 일반 계좌 15.4 %
-const ISA_TAX_RATE = 0.099; // ISA      9.9 %
+const ISA_TAX_RATE = 0.099; // ISA 9.9 %
 const DIV_YIELD = 0.02; // ETF 연 2 % 배당률
 
 export const taxSaving = async () => {
-  /* 1) 세션 & ISA */
+  /* 1) 세션 & ISA 정보 */
   const s = await getServerSession(authOptions);
   if (!s?.user?.id) throw new Error('로그인 필요');
   const userId = Number(s.user.id);
@@ -25,10 +26,10 @@ export const taxSaving = async () => {
   const isaId = isa.id;
   const limit = isa.accountType === '서민형' ? 4_000_000 : 2_000_000;
 
-  /* 2) 경과 월 */
+  /* 2) 경과 월 계산(1‒12) */
   const months = new Date().getMonth() + 1;
 
-  /* 3) net → gross 배당·이자 */
+  /* 3) 배당·이자: net → gross(세전) */
   const [intAgg, divAgg] = await Promise.all([
     prisma.generalTransaction.aggregate({
       where: { isaAccountId: isaId, transactionType: 'INTEREST' },
@@ -41,9 +42,9 @@ export const taxSaving = async () => {
   ]);
   const netDiv =
     (intAgg._sum.price?.toNumber() ?? 0) + (divAgg._sum.price?.toNumber() ?? 0);
-  const grossDiv = netDiv / (1 - TAX_INT_DIV); // 15.4 % 역환산
+  const grossDiv = netDiv; // 역산 생략
 
-  /* 4) ETF 손익 & 추정 배당(gross) */
+  /* 4) ETF 평가이익·예상 배당(gross) */
   const hlds = await prisma.eTFHolding.findMany({
     where: { isaAccountId: isaId },
     select: {
@@ -54,27 +55,30 @@ export const taxSaving = async () => {
     },
   });
 
-  let unAll = 0,
-    unOver = 0,
-    estDiv = 0;
+  let unAll = 0; // 미실현 총 평가이익(국내+해외)
+  let unOver = 0; // 미실현 해외 평가이익
+  let estDiv = 0; // 보유 ETF 예상 배당(gross)
+
   for (const h of hlds) {
     const cost = h.avgCost.toNumber() * h.quantity.toNumber();
+
     const px = await prisma.etfDailyTrading.findFirst({
       where: { etfId: h.etfId },
       orderBy: { baseDate: 'desc' },
       select: { tddClosePrice: true },
     });
     const price = px?.tddClosePrice?.toNumber() ?? h.avgCost.toNumber();
+
     const evalV = price * h.quantity.toNumber();
-    const prft = evalV - cost;
+    const prft = evalV - cost; // 평가이익(+)/손실(−)
 
     unAll += prft;
     if (h.etf.idxMarketType === '해외') unOver += prft;
 
-    estDiv += evalV * DIV_YIELD * (months / 12); // ETF 예상 배당(gross)
+    estDiv += evalV * DIV_YIELD * (months / 12); // 올해 받게 될 예상 배당(gross)
   }
 
-  /* 5) 실현 해외 ETF 차익 */
+  /* 5) 해외 ETF 실현 차익 */
   const [sell, buy] = await Promise.all([
     prisma.eTFTransaction.aggregate({
       where: {
@@ -96,38 +100,38 @@ export const taxSaving = async () => {
   const realizedOver =
     (sell._sum.price?.toNumber() ?? 0) - (buy._sum.price?.toNumber() ?? 0);
 
-  /* 6) 배당·이자(gross) 합산 → 일반 계좌 과세 손익 */
+  /* === “만기 가정” 핵심 수정 ===
+     해외 ETF 이익 = 이미 실현 + (현 시점에서 매도 시) 미실현 */
+  const totalOverseaGain = Math.max(0, realizedOver) + unOver;
+
+  /* 6) 배당·이자(gross) */
   const genDiv = grossDiv + estDiv;
 
-  /* 7) 대시보드 누적 손익 */
-  const totalProfitAll = genDiv + unAll; // 배당·이자 + ETF 全평가이익
+  /* 7) 누적 손익(참고용) */
+  const totalProfitAll = genDiv + unAll; // 배당·이자 + ETF 전체 평가이익
 
-  /* 8) 일반 계좌 과세 손익 & 세액 */
-  const totalTaxableGeneral = genDiv + unOver;
+  /* 8) 일반계좌 과세 표준 & 세액 (15.4 %) */
+  const totalTaxableGeneral = genDiv + totalOverseaGain;
   const generalAccountTax = totalTaxableGeneral * TAX_INT_DIV;
 
-  /* 9) ISA 한도·세액 (배당·이자 + 해외 ETF 모두 포함) */
-  const usedLimit = // 한도 사용액
-    grossDiv + // 배당·이자(gross)
-    Math.max(0, realizedOver); // 실현 해외 ETF 차익
+  /* 9) ISA 한도 사용액 & 과세표준(초과분만 9.9 %) */
+  // const usedLimit = grossDiv + totalOverseaGain;
+  const usedLimit = Math.min(limit, grossDiv + estDiv + totalOverseaGain);
   const remainingLimit = Math.max(0, limit - usedLimit);
 
-  const isaTaxBase = Math.max(
-    0, // 과세표준
-    grossDiv + estDiv + unOver - limit // 배당·이자(gross)+ETF 해외이익 − 한도
-  );
+  const isaTaxBase = Math.max(0, grossDiv + estDiv + totalOverseaGain - limit);
   const isaTax = isaTaxBase * ISA_TAX_RATE;
 
   /* 10) 절세 효과 */
   const savedTax = Math.max(0, generalAccountTax - isaTax);
 
   return {
-    totalTaxableGeneral, // 일반 계좌 과세 손익
+    totalTaxableGeneral, // 일반계좌 과세 손익(세전)
     unrealizedOversea: unOver,
-    generalAccountTax,
-    usedLimit, // ISA 공제 전 세액
-    isaTax,
-    savedTax,
+    generalAccountTax, // 일반계좌 세액
+    usedLimit, // ISA 비과세 한도 사용액
+    isaTax, // ISA 세액
+    savedTax, // 절세 효과(차이)
     remainingTaxFreeLimit: remainingLimit,
     limit,
   };