EmailBill/WebApi.Test/Budget/BudgetItemCalculatorTest.cs

using Service.Budget;

namespace WebApi.Test.Budget;

/// <summary>
/// BudgetItemCalculator 单元测试
/// 测试明细项计算用金额的各种规则
/// </summary>
public class BudgetItemCalculatorTest : BaseTest
{
    [Fact]
    public void 收入项实际已发生_应返回实际值()
    {
        // Arrange
        var budgetLimit = 10000m;
        var actualAmount = 9500m;
        
        // Act
        var result = BudgetItemCalculator.CalculateEffectiveAmount(
            BudgetCategory.Income,
            budgetLimit,
            actualAmount,
            isMandatory: false,
            isArchived: false,
            new DateTime(2026, 2, 15),
            BudgetPeriodType.Month
        );
        
        // Assert
        result.Should().Be(9500m);
    }

    [Fact]
    public void 收入项实际未发生_应返回预算值()
    {
        // Arrange
        var budgetLimit = 5000m;
        var actualAmount = 0m;
        
        // Act
        var result = BudgetItemCalculator.CalculateEffectiveAmount(
            BudgetCategory.Income,
            budgetLimit,
            actualAmount,
            isMandatory: false,
            isArchived: false,
            new DateTime(2026, 2, 15),
            BudgetPeriodType.Month
        );
        
        // Assert
        result.Should().Be(5000m);
    }

    [Fact]
    public void 支出项普通情况_应返回MAX预算和实际()
    {
        // Arrange
        var budgetLimit = 2000m;
        var actualAmount = 2500m;
        
        // Act
        var result = BudgetItemCalculator.CalculateEffectiveAmount(
            BudgetCategory.Expense,
            budgetLimit,
            actualAmount,
            isMandatory: false,
            isArchived: false,
            new DateTime(2026, 2, 15),
            BudgetPeriodType.Month
        );
        
        // Assert
        result.Should().Be(2500m);
    }

    [Fact]
    public void 支出项未超预算_应返回预算值()
    {
        // Arrange
        var budgetLimit = 2000m;
        var actualAmount = 1800m;
        
        // Act
        var result = BudgetItemCalculator.CalculateEffectiveAmount(
            BudgetCategory.Expense,
            budgetLimit,
            actualAmount,
            isMandatory: false,
            isArchived: false,
            new DateTime(2026, 2, 15),
            BudgetPeriodType.Month
        );
        
        // Assert
        result.Should().Be(2000m);
    }

    [Fact]
    public void 支出项超预算_应返回实际值()
    {
        // Arrange
        var budgetLimit = 2000m;
        var actualAmount = 2500m;
        
        // Act
        var result = BudgetItemCalculator.CalculateEffectiveAmount(
            BudgetCategory.Expense,
            budgetLimit,
            actualAmount,
            isMandatory: false,
            isArchived: false,
            new DateTime(2026, 2, 15),
            BudgetPeriodType.Month
        );
        
        // Assert
        result.Should().Be(2500m);
    }

    [Fact]
    public void 支出项硬性且实际为0_月度_应按天数折算()
    {
        // Arrange
        var budgetLimit = 3000m;
        var actualAmount = 0m;
        var date = new DateTime(2026, 2, 15); // 2月共28天，当前15号
        
        // Act
        var result = BudgetItemCalculator.CalculateEffectiveAmount(
            BudgetCategory.Expense,
            budgetLimit,
            actualAmount,
            isMandatory: true,
            isArchived: false,
            date,
            BudgetPeriodType.Month
        );
        
        // Assert
        var expected = 3000m / 28 * 15; // ≈ 1607.14
        result.Should().BeApproximately(expected, 0.01m);
    }

    [Fact]
    public void 支出项硬性且实际为0_年度_应按天数折算()
    {
        // Arrange
        var budgetLimit = 12000m;
        var actualAmount = 0m;
        var date = new DateTime(2026, 2, 15); // 2026年第46天（31+15）
        
        // Act
        var result = BudgetItemCalculator.CalculateEffectiveAmount(
            BudgetCategory.Expense,
            budgetLimit,
            actualAmount,
            isMandatory: true,
            isArchived: false,
            date,
            BudgetPeriodType.Year
        );
        
        // Assert
        var expected = 12000m / 365 * 46; // ≈ 1512.33
        result.Should().BeApproximately(expected, 0.01m);
    }

    [Fact]
    public void 支出项硬性且实际大于0_应返回MAX值()
    {
        // Arrange
        var budgetLimit = 3000m;
        var actualAmount = 3200m;
        
        // Act
        var result = BudgetItemCalculator.CalculateEffectiveAmount(
            BudgetCategory.Expense,
            budgetLimit,
            actualAmount,
            isMandatory: true,
            isArchived: false,
            new DateTime(2026, 2, 15),
            BudgetPeriodType.Month
        );
        
        // Assert
        result.Should().Be(3200m);
    }

    [Fact]
    public void 归档数据_应直接返回实际值()
    {
        // Arrange
        var budgetLimit = 2000m;
        var actualAmount = 1800m;
        
        // Act
        var result = BudgetItemCalculator.CalculateEffectiveAmount(
            BudgetCategory.Expense,
            budgetLimit,
            actualAmount,
            isMandatory: false,
            isArchived: true, // 归档数据
            new DateTime(2026, 2, 15),
            BudgetPeriodType.Month
        );
        
        // Assert
        result.Should().Be(1800m); // 归档数据直接返回实际值，不走MAX逻辑
    }

    [Fact]
    public void 闰年2月按天折算边界情况()
    {
        // Arrange
        var budgetLimit = 3000m;
        var actualAmount = 0m;
        var date = new DateTime(2024, 2, 29); // 闰年2月29日
        
        // Act
        var result = BudgetItemCalculator.CalculateEffectiveAmount(
            BudgetCategory.Expense,
            budgetLimit,
            actualAmount,
            isMandatory: true,
            isArchived: false,
            date,
            BudgetPeriodType.Month
        );
        
        // Assert
        var expected = 3000m / 29 * 29; // = 3000
        result.Should().Be(expected);
    }

    [Fact]
    public void 平年2月按天折算边界情况()
    {
        // Arrange
        var budgetLimit = 3000m;
        var actualAmount = 0m;
        var date = new DateTime(2026, 2, 28); // 平年2月28日
        
        // Act
        var result = BudgetItemCalculator.CalculateEffectiveAmount(
            BudgetCategory.Expense,
            budgetLimit,
            actualAmount,
            isMandatory: true,
            isArchived: false,
            date,
            BudgetPeriodType.Month
        );
        
        // Assert
        var expected = 3000m / 28 * 28; // = 3000
        result.Should().Be(expected);
    }
}