lxq/mydreamjob-server/src/test/java/com/mydreamjob/salarycalculator/SalaryCalculationEngineTest.java

package com.mydreamjob.salarycalculator;

import com.mydreamjob.common.exception.BusinessException;
import com.mydreamjob.common.exception.ErrorCode;
import org.junit.jupiter.api.Test;

import java.math.BigDecimal;
import java.time.LocalDate;

import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.assertThatThrownBy;

class SalaryCalculationEngineTest {

    private final SalaryCalculationEngine engine = new SalaryCalculationEngine();

    @Test
    void calculatesBaseCaseWithCumulativeWithholding() {
        SalaryCalculationResult result = engine.calculate(input("10000", 1, "0", null), policy());

        assertThat(result.getSocialSecurityBase()).isEqualByComparingTo("10000.00");
        assertThat(result.getHousingFundBase()).isEqualByComparingTo("10000.00");
        assertThat(result.getPension()).isEqualByComparingTo("800.00");
        assertThat(result.getMedical()).isEqualByComparingTo("200.00");
        assertThat(result.getUnemployment()).isEqualByComparingTo("50.00");
        assertThat(result.getHousingFund()).isEqualByComparingTo("1200.00");
        assertThat(result.getCurrentMonthTax()).isEqualByComparingTo("82.50");
        assertThat(result.getNetSalary()).isEqualByComparingTo("7667.50");
        assertThat(result.isEstimate()).isTrue();
        assertThat(result.getDataLevel()).isEqualTo(SalaryDataLevel.CITY);
    }

    @Test
    void clampsBothBasesToFloorAndCeiling() {
        SalaryCalculationResult low = engine.calculate(input("3000", 1, "0", null), policy());
        SalaryCalculationResult high = engine.calculate(input("30000", 1, "0", null), policy());

        assertThat(low.getSocialSecurityBase()).isEqualByComparingTo("5000.00");
        assertThat(low.getHousingFundBase()).isEqualByComparingTo("5000.00");
        assertThat(low.getCurrentMonthTax()).isEqualByComparingTo("0.00");
        assertThat(low.getNetSalary()).isEqualByComparingTo("1875.00");

        assertThat(high.getSocialSecurityBase()).isEqualByComparingTo("20000.00");
        assertThat(high.getHousingFundBase()).isEqualByComparingTo("20000.00");
        assertThat(high.getCurrentMonthTax()).isEqualByComparingTo("615.00");
        assertThat(high.getNetSalary()).isEqualByComparingTo("24885.00");
    }

    @Test
    void usesPriorCumulativeTaxForTwelfthMonth() {
        SalaryCalculationResult result = engine.calculate(input("20000", 12, "0", null), policy());

        assertThat(result.getCumulativeTaxableIncome()).isEqualByComparingTo("126000.00");
        assertThat(result.getCumulativeTaxDue()).isEqualByComparingTo("10080.00");
        assertThat(result.getPreviouslyWithheldTax()).isEqualByComparingTo("9030.00");
        assertThat(result.getCurrentMonthTax()).isEqualByComparingTo("1050.00");
        assertThat(result.getNetSalary()).isEqualByComparingTo("14450.00");
    }

    @Test
    void appliesSpecialDeductionAndOverrides() {
        SalaryOverrideParameters overrides = SalaryOverrideParameters.builder()
                .socialSecurityBase(new BigDecimal("8000.00"))
                .housingFundBase(new BigDecimal("10000.00"))
                .pensionRate(new BigDecimal("0.08"))
                .medicalRate(new BigDecimal("0.02"))
                .unemploymentRate(new BigDecimal("0.005"))
                .housingFundRate(new BigDecimal("0.12"))
                .seriousIllnessMonthlyFee(BigDecimal.ZERO)
                .build();

        SalaryCalculationResult result = engine.calculate(
                input("10000", 1, "2000", overrides), policy());

        assertThat(result.getSocialSecurityBase()).isEqualByComparingTo("8000.00");
        assertThat(result.getPension()).isEqualByComparingTo("640.00");
        assertThat(result.getCurrentMonthTax()).isEqualByComparingTo("28.80");
        assertThat(result.getNetSalary()).isEqualByComparingTo("7931.20");
    }

    @Test
    void rejectsOverrideOutsideCityBaseRange() {
        SalaryOverrideParameters overrides = SalaryOverrideParameters.builder()
                .socialSecurityBase(new BigDecimal("4999.99"))
                .build();

        assertThatThrownBy(() -> engine.calculate(input("10000", 1, "0", overrides), policy()))
                .isInstanceOf(BusinessException.class)
                .extracting(ex -> ((BusinessException) ex).getErrorCodeInt())
                .isEqualTo(ErrorCode.SALARY_INVALID_PARAMETER.getCode());
    }

    @Test
    void zeroContributionRateAllowsZeroBase() {
        SalaryOverrideParameters overrides = SalaryOverrideParameters.builder()
                .socialSecurityBase(BigDecimal.ZERO)
                .housingFundBase(BigDecimal.ZERO)
                .pensionRate(BigDecimal.ZERO)
                .medicalRate(BigDecimal.ZERO)
                .unemploymentRate(BigDecimal.ZERO)
                .housingFundRate(BigDecimal.ZERO)
                .seriousIllnessMonthlyFee(BigDecimal.ZERO)
                .build();

        SalaryCalculationResult result = engine.calculate(
                input("10000", 1, "0", overrides), policy());

        assertThat(result.getPension()).isEqualByComparingTo("0.00");
        assertThat(result.getMedical()).isEqualByComparingTo("0.00");
        assertThat(result.getUnemployment()).isEqualByComparingTo("0.00");
        assertThat(result.getHousingFund()).isEqualByComparingTo("0.00");
        assertThat(result.getCurrentMonthTax()).isEqualByComparingTo("150.00");
        assertThat(result.getNetSalary()).isEqualByComparingTo("9850.00");
    }

    private SalaryCalculationInput input(
            String gross, int monthIndex, String specialDeduction,
            SalaryOverrideParameters overrides) {
        return SalaryCalculationInput.builder()
                .grossMonthlySalary(new BigDecimal(gross))
                .monthIndex(monthIndex)
                .specialAdditionalDeduction(new BigDecimal(specialDeduction))
                .overrides(overrides)
                .build();
    }

    private SalaryCityPolicy policy() {
        return SalaryCityPolicy.builder()
                .cityCode("110000")
                .provinceCode("110000")
                .provinceName("北京市")
                .cityName("北京市")
                .policyVersion("2026-09-20-v1")
                .policyEffectiveDate(LocalDate.of(2026, 7, 1))
                .socialSecurityBaseMin(new BigDecimal("5000.00"))
                .socialSecurityBaseMax(new BigDecimal("20000.00"))
                .housingFundBaseMin(new BigDecimal("5000.00"))
                .housingFundBaseMax(new BigDecimal("20000.00"))
                .pensionRate(new BigDecimal("0.080000"))
                .medicalRate(new BigDecimal("0.020000"))
                .unemploymentRate(new BigDecimal("0.005000"))
                .housingFundRate(new BigDecimal("0.120000"))
                .seriousIllnessMonthlyFee(BigDecimal.ZERO)
                .dataLevel(SalaryDataLevel.CITY)
                .enabled(true)
                .build();
    }
}