Initial

TaxCalculator.UnitTests/GlobalUsings.cs

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+global using Xunit;

TaxCalculator.UnitTests/SalaryServiceTests.cs

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+using Moq;
+using TaxCalculator.Api.Services;
+
+namespace TaxCalculator.UnitTests
+{
+    public class SalaryServiceTests
+    {
+        [Theory]
+        [InlineData(10000, 833.33, 9000, 750, 1000.00, 83.33)]
+        [InlineData(40000, 3333.33, 29000, 2416.67, 11000.00, 916.67)]
+        public async Task CalculateSalaryDetails_ReturnsCorrectResult(
+            int grossAnnualSalary, decimal grossMonthlySalary, decimal netAnnualSalary, decimal netMonthlySalary,
+            decimal annualTaxPaid, decimal monthlyTaxPaid)
+        {
+            // Arrange
+            var taxCalculatorMock = new Mock<ITaxCalculatorService>();
+            taxCalculatorMock.Setup(tc => tc.CalculateTax(It.IsAny<int>()))
+                .Returns(Task.FromResult(annualTaxPaid));
+
+            var salaryService = new SalaryService(taxCalculatorMock.Object);
+
+            // Act
+            var result = await salaryService.CalculateSalaryDetails(grossAnnualSalary);
+
+            // Assert
+            Assert.NotNull(result);
+            Assert.Equal(grossAnnualSalary, result.GrossAnnualSalary);
+            Assert.Equal(grossMonthlySalary, result.GrossMonthlySalary);
+            Assert.Equal(netAnnualSalary, result.NetAnnualSalary);
+            Assert.Equal(netMonthlySalary, result.NetMonthlySalary);
+            Assert.Equal(annualTaxPaid, result.AnnualTaxPaid);
+            Assert.Equal(monthlyTaxPaid, result.MonthlyTaxPaid);
+        }
+
+        [Fact]
+        public async Task CalculateSalaryDetails_ThrowsException_ForNegativeSalary()
+        {
+            // Arrange
+            var taxCalculatorMock = new Mock<ITaxCalculatorService>();
+            taxCalculatorMock.Setup(tc => tc.CalculateTax(It.IsAny<int>())).Returns(Task.FromResult((decimal)0));
+
+            var salaryService = new SalaryService(taxCalculatorMock.Object);
+            var negativeSalary = -5000;
+
+            // Act & Assert
+            var exception =
+                await Assert.ThrowsAsync<ArgumentException>(async () => await salaryService.CalculateSalaryDetails(negativeSalary));
+            
+            Assert.Equal("Gross annual salary must be non-negative.", exception.Message);
+        }
+    }
+}

TaxCalculator.UnitTests/TaxCalculator.UnitTests.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.6.0" />
+    <PackageReference Include="Moq" Version="4.20.69" />
+    <PackageReference Include="xunit" Version="2.4.2" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="coverlet.collector" Version="6.0.0">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\TaxCalculator.Api\TaxCalculator.Api.csproj" />
+  </ItemGroup>
+
+</Project>

TaxCalculator.UnitTests/TaxCalculatorServiceTests.cs

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+namespace TaxCalculator.UnitTests
+{
+    using DAL;
+    using Domain;
+    using Moq;
+    using TaxCalculator.Api.Services;
+
+    public class TaxCalculatorServiceTests
+    {
+        [Theory]
+        [InlineData(5000, 0, 0)] // Example test case for Band A
+        [InlineData(15000, 20, 3000)] // Example test case for Band B
+        [InlineData(30000, 40, 12000)] // Example test case for Band C
+        // Add more test cases as needed
+        public async Task CalculateTax_ReturnsCorrectResult(
+            int annualSalary, int taxRate, int expectedTax)
+        {
+            // Arrange
+            var taxBandRepositoryMock = new Mock<ITaxBandRepository>();
+            taxBandRepositoryMock.Setup(repo => repo.GetTaxBands()).Returns(Task.FromResult(new List<TaxBand>
+            {
+                new TaxBand { LowerLimit = 0, UpperLimit = null, TaxRate = taxRate }
+            }));
+
+            var taxCalculator = new TaxCalculatorService(taxBandRepositoryMock.Object);
+
+            // Act
+            var result = await taxCalculator.CalculateTax(annualSalary);
+
+            // Assert
+            Assert.Equal(expectedTax, result);
+        }
+
+        [Fact]
+        public async Task CalculateTax_ThrowsException_ForNegativeSalary()
+        {
+            // Arrange
+            var taxBandRepositoryMock = new Mock<ITaxBandRepository>();
+            var taxCalculator = new TaxCalculatorService(taxBandRepositoryMock.Object);
+
+            // Act & Assert
+            var exception = await Assert.ThrowsAsync<ArgumentException>(async () => await taxCalculator.CalculateTax(-5000));
+            Assert.Equal("Gross annual salary must be non-negative.", exception.Message);
+        }
+    }
+}