feat: Replace FluentAssertions with Shouldly in Chapter 4

Chapter-4-applying-tactical-domain-driven-design/Docs/ArchitectureDecisionLog/0026-select-assertion-framework.adoc

@@ -0,0 +1,44 @@
+= 26. Select Fluent Assertion Alternative Due to Licensing Issue
+
+Date: 2025-09-04
+
+== Problem
+
+We have been using Fluent Assertions as an assertion library to enhance the readability and maintainability of our test code through fluent interfaces. However, starting from version 8, Fluent Assertions has transitioned to a paid NuGet package. Given the current pricing model, the cost outweighs the benefits it provides to our project. Consequently, we are evaluating open-source alternatives to replace Fluent Assertions.
+
+=== Option 1: NFluentAssertions
+
+This library is a fork of Fluent Assertions, allowing us to transition without modifying our existing assertions—only a NuGet package change is required.
+
+The project is maintained by a separate group of developers, raising concerns about its long-term stability and ongoing support.
+
+Repository: https://github.com/tpierrain/NFluent
+
+=== Option 2: MSTest Assertions
+
+These assertions are the standard Microsoft .NET testing utilities, maintained and updated with each .NET release.
+
+They offer a reliable and well-supported alternative but lack the fluent syntax, resulting in assertions that are less readable and more verbose.
+
+Documentation: https://learn.microsoft.com/en-us/dotnet/core/testing/unit-testing-with-mstest
+
+=== Option 3: Shouldly
+
+Shouldly provides a similar fluent interface to Fluent Assertions with minor syntactic differences.
+
+It is widely supported, maintained by an active community of contributors, and backed by sponsors, ensuring its long-term viability.
+
+The primary downside is the need to refactor existing assertions to align with Shouldly’s syntax.
+
+Repository: https://github.com/shouldly/shouldly
+
+== Decision
+
+After a thorough analysis of available options, we have decided to migrate from Fluent Assertions to Shouldly.
+
+== Consequences
+- Improved Long-Term Stability: Shouldly is actively maintained and supported by the open-source community, reducing the risk of unexpected licensing changes.
+- Maintainability & Readability: Shouldly retains a fluent syntax, ensuring our tests remain easy to read and maintain.
+- Refactoring Effort: Transitioning to Shouldly requires refactoring existing assertions, introducing short-term overhead but ensuring long-term sustainability.
+- Cost Reduction: Moving away from a paid assertion library eliminates unnecessary expenditure while maintaining similar functionality.
+- Ecosystem Alignment: Shouldly is widely adopted in the .NET ecosystem, ensuring compatibility and integration with modern development workflows.

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Common/Fitnet.Common.Api.UnitTests/ExceptionMiddlewareTests.cs

@@ -7,7 +7,6 @@ namespace EvolutionaryArchitecture.Fitnet.Common.Api.UnitTests;
 using ErrorHandling;
 using Microsoft.AspNetCore.Http;
 using Newtonsoft.Json;
-using Shouldly;
 using Xunit;
 
 public sealed class ExceptionMiddlewareTests

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Common/Fitnet.Common.Api.UnitTests/GlobalUsings.cs

@@ -1,5 +1 @@
-global using System.Net;
-global using Xunit;
-global using FluentAssertions;
-global using Microsoft.AspNetCore.Http;
-global using Newtonsoft.Json;
+global using Shouldly;

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Common/Fitnet.Common.Core.UnitTests/GlobalUsings.cs

@@ -1,3 +1,2 @@
 global using Xunit;
-global using FluentAssertions;
 global using Shouldly;

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Common/Fitnet.Common.Core.UnitTests/ValueObjectTests.cs

@@ -1,5 +1,9 @@
 namespace EvolutionaryArchitecture.Fitnet.Common.Core.UnitTests;
 
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
 public class ValueObjectTests
 {
     private const int DefaultIntProperty = 1;
@@ -13,10 +17,10 @@ internal void Given_two_same_type_objects_When_values_are_the_same_Then_should_b
         var secondObject = new FakeValueObject();
 
         // Act & Assert
-        firstObject.Should().Be(secondObject);
-        firstObject.Equals(secondObject).Should().BeTrue();
-        (firstObject == secondObject).Should().BeTrue();
-        (firstObject != secondObject).Should().BeFalse();
+        firstObject.ShouldBe(secondObject);
+        firstObject.Equals(secondObject).ShouldBeTrue();
+        (firstObject == secondObject).ShouldBeTrue();
+        (firstObject != secondObject).ShouldBeFalse();
     }
 
     [Fact]
@@ -28,14 +32,14 @@ internal void Given_two_same_type_objects_When_values_are_not_the_same_Then_shou
         var thirdObject = new FakeValueObject(property2: Guid.NewGuid().ToString());
 
         // Act & Assert
-        firstObject.Should().NotBe(secondObject);
-        firstObject.Equals(secondObject).Should().BeFalse();
-        (firstObject == secondObject).Should().BeFalse();
-        (firstObject != secondObject).Should().BeTrue();
-        firstObject.Should().NotBe(thirdObject);
-        firstObject.Equals(thirdObject).Should().BeFalse();
-        (firstObject == thirdObject).Should().BeFalse();
-        (firstObject != thirdObject).Should().BeTrue();
+        firstObject.ShouldNotBe(secondObject);
+        firstObject.Equals(secondObject).ShouldBeFalse();
+        (firstObject == secondObject).ShouldBeFalse();
+        (firstObject != secondObject).ShouldBeTrue();
+        firstObject.ShouldNotBe(thirdObject);
+        firstObject.Equals(thirdObject).ShouldBeFalse();
+        (firstObject == thirdObject).ShouldBeFalse();
+        (firstObject != thirdObject).ShouldBeTrue();
     }
 
     [Fact]
@@ -46,7 +50,7 @@ internal void Given_two_same_type_objects_When_values_are_the_same_Then_should_h
         var secondObject = new FakeValueObject();
 
         // Act & Assert
-        firstObject.GetHashCode().Should().Be(secondObject.GetHashCode());
+        firstObject.GetHashCode().ShouldBe(secondObject.GetHashCode());
     }
 
     [Fact]
@@ -57,10 +61,10 @@ internal void Given_two_different_type_objects_When_values_are_the_same_Then_sho
         var secondObject = new AnotherTypeFakeValueObject();
 
         // Act & Assert
-        firstObject.Should().NotBe(secondObject);
-        firstObject.Equals(secondObject).Should().BeFalse();
-        (firstObject == secondObject).Should().BeFalse();
-        (firstObject != secondObject).Should().BeTrue();
+        firstObject.GetType().ShouldNotBe(secondObject.GetType());
+        firstObject.Equals(secondObject).ShouldBeFalse();
+        (firstObject == secondObject).ShouldBeFalse();
+        (firstObject != secondObject).ShouldBeTrue();
     }
 
     [Fact]
@@ -80,8 +84,8 @@ internal void Given_multiple_objects_When_looking_for_specific_one_Then_should_r
         var result = valueObjects.Where(vo => vo == targetValueObject).ToList();
 
         // Assert
-        result.Should().HaveCount(2);
-        result.Should().AllBeEquivalentTo(targetValueObject);
+        result.Count.ShouldBe(2);
+        result.ForEach(vo => vo.ShouldBe(targetValueObject));
     }
 
     [Fact]
@@ -101,7 +105,7 @@ internal void Given_multiple_objects_When_looking_for_non_existing_one_Then_shou
         var result = valueObjects.Where(vo => vo == targetValueObject).ToList();
 
         // Assert
-        result.Should().BeEmpty();
+        result.ShouldBeEmpty();
     }
 
     private class FakeValueObject(int property1 = DefaultIntProperty, string property2 = DefaultStringProperty) : ValueObject

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Common/Fitnet.Common.IntegrationTestsToolbox/GlobalUsings.cs

@@ -1,6 +1,5 @@
 global using System.Reflection;
 global using JetBrains.Annotations;
-global using Xunit;
 global using Microsoft.AspNetCore.Mvc.Testing;
 global using Microsoft.AspNetCore.Hosting;
 global using Microsoft.Extensions.Configuration;

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Common/Fitnet.Common.IntegrationTestsToolbox/TestEngine/Database/IDatabaseConfiguration.cs

@@ -2,5 +2,5 @@ namespace EvolutionaryArchitecture.Fitnet.Common.IntegrationTestsToolbox.TestEng
 
 public interface IDatabaseConfiguration
 {
-    public Dictionary<string, string?> Get();
-}
+    Dictionary<string, string?> Get();
+}

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Common/Fitnet.Common.IntegrationTestsToolbox/TestEngine/EventBus/EventBusExtensions.cs

@@ -54,6 +54,6 @@ public static async Task<IEnumerable<IReceivedMessage<TMessage>>> WaitToConsumeM
             }
         }
 
-        return testHarness.Consumed!.Select<TMessage>(cancellationToken)!.ToList();
+        return [.. testHarness.Consumed!.Select<TMessage>(cancellationToken)!];
     }
 }

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Contracts/Src/Fitnet.Contracts.Api.UnitTests/Fitnet.Contracts.Api.UnitTests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <ItemGroup>
     <PackageReference Include="Bogus" Version="35.6.1" />
-    <PackageReference Include="FluentAssertions" Version="7.0.0" />
+    <PackageReference Include="Shouldly" Version="4.3.0" />
     <PackageReference Include="JetBrains.Annotations" Version="2024.3.0" />
     <PackageReference Include="xunit" Version="2.9.2" />
     <PackageReference Include="xunit.analyzers" Version="1.18.0">

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Contracts/Src/Fitnet.Contracts.Api.UnitTests/GlobalUsings.cs

@@ -1,2 +1,4 @@
+global using System;
 global using Bogus;
+global using Shouldly;
 global using Xunit;

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Contracts/Src/Fitnet.Contracts.Api.UnitTests/SignContract/Signatures/SignatureTests.cs

@@ -1,8 +1,6 @@
 namespace EvolutionaryArchitecture.Fitnet.Contracts.Api.UnitTests.SignContract.Signatures;
 using EvolutionaryArchitecture.Fitnet.Contracts.Core.SignContract.Signatures;
-
 using Core.SignContract.Signatures.Exceptions;
-using FluentAssertions;
 
 public sealed class SignatureTests
 {
@@ -20,8 +18,8 @@ internal void Given_create_signature_When_signature_is_valid_Then_should_not_thr
         var signature = Signature.From(now, value);
 
         // Assert
-        signature.Value.Should().Be(value);
-        signature.Date.Should().Be(now);
+        signature.Value.ShouldBe(value);
+        signature.Date.ShouldBe(now);
     }
 
     [Theory]
@@ -33,9 +31,12 @@ internal void Given_create_signature_When_signature_has_forbidden_characters_The
         var now = DateTimeOffset.Now;
 
         // Act
-        Action act = () => Signature.From(now, value);
+        void Act()
+        {
+            Signature.From(now, value);
+        }
 
         // Assert
-        act.Should().Throw<SignatureNotValidException>();
+        Should.Throw<SignatureNotValidException>(Act);
     }
 }

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Contracts/Src/Fitnet.Contracts.Core.UnitTests/Common/Assertions/ErrorOr/ErrorOrAssertions.cs

@@ -1,31 +1,25 @@
 namespace EvolutionaryArchitecture.Fitnet.Contracts.Core.UnitTests.Common.Assertions.ErrorOr;
 
-using FluentAssertions.Execution;
-using FluentAssertions.Primitives;
+using System.Linq;
 
-internal sealed class ErrorOrSuccessAssertions(ErrorOr<Success> subject)
-    : ReferenceTypeAssertions<ErrorOr<Success>, ErrorOrSuccessAssertions>(subject)
+public static class ErrorOrSuccessAssertions
 {
-
-    protected override string Identifier => "ErrorOr<Success>";
-
-    public AndConstraint<ErrorOr<Success>> BeSuccessful(string because = "", params object[] becauseArgs)
+    public static void ShouldBeSuccessful(this ErrorOr<Success> errorOr, string? message = null)
     {
-        Execute.Assertion
-            .ForCondition(!Subject.IsError)
-            .BecauseOf(because, becauseArgs)
-            .FailWith("Expected {context:ErrorOr<Success>} to be successful{reason}, but found {0}.", string.Join(", ", Subject.Errors.Select(x => x.Description)));
-
-        return new AndConstraint<ErrorOr<Success>>(Subject);
+        if (errorOr.IsError)
+        {
+            var errorMessage = string.Join(", ", errorOr.Errors.Select(x => x.Description));
+            throw new ShouldAssertException(message ?? $"ErrorOr<Success> should be successful but found errors: {errorMessage}");
+        }
     }
 
-    public AndConstraint<ErrorOr<Success>> ContainError(Error error, string because = "", params object[] becauseArgs)
+    public static void ShouldContainError(this ErrorOr<Success> errorOr, Error error, string? message = null)
     {
-        Execute.Assertion
-            .ForCondition(Subject.IsError && Subject.Errors.Contains(error))
-            .BecauseOf(because, becauseArgs)
-            .FailWith("Expected to contain error '{0}' but found errors: {1}", string.Join(", ", Subject.Errors.Select(x => x.Description)), error.Description);
-
-        return new AndConstraint<ErrorOr<Success>>(Subject);
+        errorOr.IsError.ShouldBeTrue("ErrorOr<Success> should be in error state");
+        if (!errorOr.Errors.Contains(error))
+        {
+            var actualErrors = string.Join(", ", errorOr.Errors.Select(x => x.Description));
+            throw new ShouldAssertException(message ?? $"Expected to contain error '{error.Description}' but found errors: {actualErrors}");
+        }
     }
 }

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Contracts/Src/Fitnet.Contracts.Core.UnitTests/Fitnet.Contracts.Core.UnitTests.csproj

@@ -8,7 +8,7 @@
         <PackageReference Include="Bogus" Version="35.6.1" />
         <PackageReference Include="EvolutionaryArchitecture.Fitnet.Common.Core" Version="4.1.7" />
         <PackageReference Include="EvolutionaryArchitecture.Fitnet.Common.UnitTesting" Version="4.1.7" />
-        <PackageReference Include="FluentAssertions" Version="6.12.0" />
+        <PackageReference Include="Shouldly" Version="4.3.0" />
         <PackageReference Include="xunit" Version="2.8.1" />
         <PackageReference Include="xunit.analyzers" Version="1.14.0">
           <PrivateAssets>all</PrivateAssets>

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Contracts/Src/Fitnet.Contracts.Core.UnitTests/GlobalUsings.cs

@@ -1,4 +1,4 @@
 global using ErrorOr;
 global using EvolutionaryArchitecture.Fitnet.Common.UnitTesting.Assertions.ErrorOr;
-global using FluentAssertions;
+global using Shouldly;
 global using Xunit;

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Contracts/Src/Fitnet.Contracts.Core.UnitTests/PrepareContract/BusinessRules/ContractCanBePreparedOnlyForAdultRuleTests.cs

@@ -1,5 +1,6 @@
 namespace EvolutionaryArchitecture.Fitnet.Contracts.Core.UnitTests.PrepareContract.BusinessRules;
 
+using Common.Assertions.ErrorOr;
 using Core.PrepareContract.BusinessRules;
 using Fitnet.Common.Core.BussinessRules;
 
@@ -16,7 +17,7 @@ internal void Given_customer_age_which_is_less_than_18_Then_validation_should_ha
         // Assert
         var expectedError = BusinessRuleError.Create(nameof(ContractCanBePreparedOnlyForAdultRule),
             "Contract can not be prepared for a person who is not adult");
-        result.Should().ContainError(expectedError);
+        result.ShouldContainError(expectedError);
     }
 
     [Fact]
@@ -28,7 +29,7 @@ internal void Given_customer_age_which_is_equal_to_18_Then_validation_should_pas
         var result = BusinessRuleValidator.Validate(new ContractCanBePreparedOnlyForAdultRule(18));
 
         // Assert
-        result.Should().BeSuccessful();
+        result.ShouldBeSuccessful();
     }
 
     [Fact]
@@ -40,6 +41,6 @@ internal void Given_customer_age_which_is_greater_than_18_Then_validation_should
         var result = BusinessRuleValidator.Validate(new ContractCanBePreparedOnlyForAdultRule(19));
 
         // Assert
-        result.Should().BeSuccessful();
+        result.ShouldBeSuccessful();
     }
 }

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Contracts/Src/Fitnet.Contracts.Core.UnitTests/PrepareContract/BusinessRules/CustomerMustBeSmallerThanMaximumHeightLimitRuleTests.cs

@@ -2,11 +2,12 @@ namespace EvolutionaryArchitecture.Fitnet.Contracts.Core.UnitTests.PrepareContra
 
 using Core.PrepareContract.BusinessRules;
 using Fitnet.Common.Core.BussinessRules;
+using Common.Assertions.ErrorOr;
 
 public sealed class CustomerMustBeSmallerThanMaximumHeightLimitRuleTests
 {
     [Fact]
-    internal void Given_customer_heigth_which_is_greater_than_maximum_height_limit_Then_validation_should_have_error()
+    internal void Given_customer_height_which_is_greater_than_maximum_height_limit_Then_validation_should_have_error()
     {
         // Arrange
         const int height = 211;
@@ -16,7 +17,7 @@ internal void Given_customer_heigth_which_is_greater_than_maximum_height_limit_T
 
         // Assert
         var expectedError = BusinessRuleError.Create(nameof(CustomerMustBeSmallerThanMaximumHeightLimitRule), "Customer height must fit maximum limit for gym instruments");
-        result.Should().ContainError(expectedError);
+        result.ShouldContainError(expectedError);
     }
 
     [Fact]
@@ -29,7 +30,7 @@ internal void Given_customer_height_which_is_equal_to_maximum_height_limit_Then_
         var result = BusinessRuleValidator.Validate(new CustomerMustBeSmallerThanMaximumHeightLimitRule(height));
 
         // Assert
-        result.Should().BeSuccessful();
+        result.ShouldBeSuccessful();
     }
 
     [Fact]
@@ -42,6 +43,6 @@ internal void Given_customer_height_which_is_less_than_maximum_height_limit_Then
         var result = BusinessRuleValidator.Validate(new CustomerMustBeSmallerThanMaximumHeightLimitRule(height));
 
         // Assert
-        result.Should().BeSuccessful();
+        result.ShouldBeSuccessful();
     }
 }

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Contracts/Src/Fitnet.Contracts.Core.UnitTests/PrepareContract/PrepareContractTests.cs

@@ -19,7 +19,7 @@ internal void Given_prepare_contract_Then_should_raise_contract_prepared_event()
         // Assert
         var contract = preparationResult.Value;
         var @event = contract.GetPublishedEvent<ContractPreparedEvent>();
-        @event?.CustomerId.Should().Be(_customerId);
-        @event?.PreparedAt.Should().Be(_preparedAt);
+        @event?.CustomerId.ShouldBe(_customerId);
+        @event?.PreparedAt.ShouldBe(_preparedAt);
     }
 }

Chapter-4-applying-tactical-domain-driven-design/Fitnet.Contracts/Src/Fitnet.Contracts.Core.UnitTests/SignContract/SignContractTests.cs

@@ -28,7 +28,7 @@ internal void Given_sign_contract_Then_expiration_date_is_set_to_contract_durati
 
         // Assert
         var @event = signResult.Value.GetPublishedEvent<BindingContractStartedEvent>();
-        @event?.ExpiringAt.Should().Be(expectedExpirationDate);
+        @event?.ExpiringAt.ShouldBe(expectedExpirationDate);
     }
 
     private static readonly DateTimeOffset FakeNow = FakeContractDates.PreparedAt.AddDays(1);
@@ -47,6 +47,6 @@ internal void Given_sign_contract_Then_contracts_becomes_binding_contract()
 
         // Assert
         var @event = signResult.Value.GetPublishedEvent<BindingContractStartedEvent>();
-        @event?.BindingFrom.Should().Be(SignedAt);
+        @event?.BindingFrom.ShouldBe(SignedAt);
     }
 }