feat: add builderConstructorMandatoryParameters option to enforce man…

Buildenator.Abstraction/BuildenatorConfigurationAttribute.cs

@@ -17,6 +17,7 @@ public sealed class BuildenatorConfigurationAttribute : Attribute
     /// <param name="generateStaticPropertyForBuilderCreation">If you want to generate static property that will return a new builder instance.</param>
     /// <param name="initializeCollectionsWithEmpty">If true, collection fields will be initialized with empty collections in the constructor instead of null.</param>
     /// <param name="useChildBuilders">If true, generates additional With methods that accept Func&lt;ChildBuilder, ChildBuilder&gt; for properties that have their own builders.</param>
+    /// <param name="builderConstructorMandatoryParameters">If true, all generated builders in this assembly will require the entity's constructor parameters as mandatory builder constructor arguments. Incompatible with mocking.</param>
     public BuildenatorConfigurationAttribute(
         string buildingMethodsPrefix = "With",
         bool generateDefaultBuildMethod = true,
@@ -25,7 +26,8 @@ public BuildenatorConfigurationAttribute(
         bool implicitCast = false,
         bool generateStaticPropertyForBuilderCreation = false,
         bool initializeCollectionsWithEmpty = true,
-        bool useChildBuilders = true)
+        bool useChildBuilders = true,
+        bool builderConstructorMandatoryParameters = false)
     {
         }
 }

Buildenator.Abstraction/MakeBuilderAttribute.cs

@@ -19,6 +19,7 @@ public sealed class MakeBuilderAttribute : Attribute
     /// <param name="generateStaticPropertyForBuilderCreation">If you want to generate static property that will return a new builder instance.</param>
     /// <param name="initializeCollectionsWithEmpty">If true, collection fields will be initialized with empty collections in the constructor instead of null.</param>
     /// <param name="useChildBuilders">If true, generates additional With methods that accept Func&lt;ChildBuilder, ChildBuilder&gt; for properties that have their own builders.</param>
+    /// <param name="builderConstructorMandatoryParameters">If true, the generated builder constructor will require the entity's constructor parameters as mandatory arguments instead of using a parameterless constructor. Incompatible with mocking.</param>
     public MakeBuilderAttribute(
         Type typeForBuilder,
         string? buildingMethodsPrefix = "With",
@@ -29,7 +30,8 @@ public MakeBuilderAttribute(
         string? staticFactoryMethodName = null,
         object? generateStaticPropertyForBuilderCreation = null,
         object? initializeCollectionsWithEmpty = null,
-        object? useChildBuilders = null
+        object? useChildBuilders = null,
+        object? builderConstructorMandatoryParameters = null
     )
     {
         }

Buildenator/AnalyzerReleases.Unshipped.md

@@ -9,4 +9,6 @@ BDN002 | Buildenator | Error | BuildersGenerator
 BDN003 | Buildenator | Info | BuildenatorDiagnosticDescriptors
 BDN004 | Buildenator | Info | BuildenatorDiagnosticDescriptors
 BDN005 | Buildenator | Info | BuildenatorDiagnosticDescriptors
-BDN006 | Buildenator | Info | BuildenatorDiagnosticDescriptors
+BDN006 | Buildenator | Info | BuildenatorDiagnosticDescriptors
+BDN007 | Buildenator | Error | BuildenatorDiagnosticDescriptors
+BDN008 | Buildenator | Error | BuildenatorDiagnosticDescriptors

Buildenator/Buildenator.csproj

@@ -9,7 +9,7 @@
     <IncludeBuildOutput>false</IncludeBuildOutput>
     <EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
     <!-- Do not include the generator as a lib dependency -->
-  <Version>8.5.0.2</Version>
+    <Version>8.8.0.0</Version>
   </PropertyGroup>
 
   <ItemGroup>

Buildenator/Configuration/BuilderProperties.cs

@@ -31,6 +31,7 @@ public static BuilderProperties Create(
         bool? generateStaticPropertyForBuilderCreation = null;
         bool? initializeCollectionsWithEmpty = null;
         bool? useChildBuilders = null;
+        bool? builderConstructorMandatoryParameters = null;
 
         if (globalAttributes.HasValue)
         {
@@ -42,6 +43,7 @@ public static BuilderProperties Create(
             generateStaticPropertyForBuilderCreation = globalAttributes.Value.GetOrThrow<bool>(5, nameof(MakeBuilderAttributeInternal.GenerateStaticPropertyForBuilderCreation));
             initializeCollectionsWithEmpty = globalAttributes.Value.GetOrThrow<bool>(6, nameof(MakeBuilderAttributeInternal.InitializeCollectionsWithEmpty));
             useChildBuilders = globalAttributes.Value.GetOrThrow<bool>(7, nameof(MakeBuilderAttributeInternal.UseChildBuilders));
+            builderConstructorMandatoryParameters = globalAttributes.Value.GetOrThrow<bool>(8, nameof(MakeBuilderAttributeInternal.BuilderConstructorMandatoryParameters));
         }
 
         nullableStrategy = builderAttribute.NullableStrategy is null ? nullableStrategy: builderAttribute.NullableStrategy;
@@ -64,7 +66,8 @@ public static BuilderProperties Create(
                 builderAttribute.StaticFactoryMethodName,
                 builderAttribute.GenerateStaticPropertyForBuilderCreation ?? generateStaticPropertyForBuilderCreation,
                 builderAttribute.InitializeCollectionsWithEmpty ?? initializeCollectionsWithEmpty,
-                builderAttribute.UseChildBuilders ?? useChildBuilders));
+                builderAttribute.UseChildBuilders ?? useChildBuilders,
+                builderAttribute.BuilderConstructorMandatoryParameters ?? builderConstructorMandatoryParameters));
     }
 
     private BuilderProperties(INamespaceOrTypeSymbol builderSymbol, MakeBuilderAttributeInternal attributeData)
@@ -82,6 +85,7 @@ private BuilderProperties(INamespaceOrTypeSymbol builderSymbol, MakeBuilderAttri
         GenerateStaticPropertyForBuilderCreation = attributeData.GenerateStaticPropertyForBuilderCreation ?? false;
         InitializeCollectionsWithEmpty = attributeData.InitializeCollectionsWithEmpty ?? true;
         UseChildBuilders = attributeData.UseChildBuilders ?? true;
+        BuilderConstructorMandatoryParameters = attributeData.BuilderConstructorMandatoryParameters ?? false;
 
         if (string.IsNullOrWhiteSpace(BuildingMethodsPrefix))
             throw new ArgumentNullException(nameof(attributeData), "Prefix name shouldn't be empty!");
@@ -182,6 +186,7 @@ private static bool IsAccessibleDefaultValueMember(bool isStatic, Accessibility
     public bool GenerateStaticPropertyForBuilderCreation { get; }
     public bool InitializeCollectionsWithEmpty { get; }
     public bool UseChildBuilders { get; }
+    public bool BuilderConstructorMandatoryParameters { get; }
 
     public IReadOnlyDictionary<string, List<IMethodSymbol>> BuildingMethods => _buildingMethods;
     public IReadOnlyDictionary<string, IFieldSymbol> Fields => _fields;

Buildenator/Configuration/Contract/IBuilderProperties.cs

@@ -27,6 +27,7 @@ internal interface IBuilderProperties
     bool GenerateStaticPropertyForBuilderCreation { get; }
     bool InitializeCollectionsWithEmpty { get; }
     bool UseChildBuilders { get; }
+    bool BuilderConstructorMandatoryParameters { get; }
 
     /// <summary>
     /// Gets the set of user-defined default value names available in this builder.

Buildenator/Diagnostics/BuildenatorDiagnosticDescriptors.cs

@@ -52,4 +52,20 @@ internal static class BuildenatorDiagnosticDescriptors
         "Buildenator",
         DiagnosticSeverity.Info,
         true);
+
+    internal static readonly DiagnosticDescriptor MandatoryParametersWithMockingDiagnostic = new(
+        "BDN007",
+        "BuilderConstructorMandatoryParameters is incompatible with mocking",
+        "The builder '{0}' has BuilderConstructorMandatoryParameters = true, which is incompatible with a mocking configuration. Remove the mocking configuration or disable BuilderConstructorMandatoryParameters.",
+        "Buildenator",
+        DiagnosticSeverity.Error,
+        true);
+
+    internal static readonly DiagnosticDescriptor MandatoryParametersWithFixtureDiagnostic = new(
+        "BDN008",
+        "BuilderConstructorMandatoryParameters is incompatible with fixture configuration",
+        "The builder '{0}' has BuilderConstructorMandatoryParameters = true, which is incompatible with a fixture configuration. Remove the fixture configuration or disable BuilderConstructorMandatoryParameters.",
+        "Buildenator",
+        DiagnosticSeverity.Error,
+        true);
 }

Buildenator/Generators/BuilderSourceStringGenerator.cs

@@ -34,6 +34,20 @@ public BuilderSourceStringGenerator(
         {
             _diagnostics.Add(privateConstructorDiagnostic);
         }
+        if (_builder.BuilderConstructorMandatoryParameters && mockingConfiguration != null)
+        {
+            _diagnostics.Add(new BuildenatorDiagnostic(
+                BuildenatorDiagnosticDescriptors.MandatoryParametersWithMockingDiagnostic,
+                _builder.OriginalLocation,
+                _builder.Name));
+        }
+        if (_builder.BuilderConstructorMandatoryParameters && fixtureConfiguration != null)
+        {
+            _diagnostics.Add(new BuildenatorDiagnostic(
+                BuildenatorDiagnosticDescriptors.MandatoryParametersWithFixtureDiagnostic,
+                _builder.OriginalLocation,
+                _builder.Name));
+        }
         _diagnostics.AddRange(_builder.Diagnostics);
         _diagnostics.AddRange(_entity.Diagnostics);
 
@@ -67,11 +81,11 @@ namespace {_builder.ContainingNamespace}
 {GenerateGlobalNullable()}{GenerateBuilderDefinition()}
     {{
 {(_fixtureConfiguration is null ? string.Empty : $"        private readonly {_fixtureConfiguration.Name} {DefaultConstants.FixtureLiteral} = new {_fixtureConfiguration.Name}({_fixtureConfiguration.ConstructorParameters});")}
-{(_builder.IsDefaultConstructorOverriden ? string.Empty : GenerateConstructor(_builder.Name, _entity, _fixtureConfiguration, _builder.InitializeCollectionsWithEmpty))}
+{(_builder.IsDefaultConstructorOverriden ? string.Empty : GenerateConstructor(_builder.Name, _entity, _fixtureConfiguration, _builder.InitializeCollectionsWithEmpty, _builder.BuilderConstructorMandatoryParameters))}
 {_propertiesStringGenerator.GeneratePropertiesCode()}
 {(_builder.IsBuildMethodOverriden ? string.Empty : _entity.GenerateBuildsCode(_builder.ShouldGenerateMethodsForUnreachableProperties))}
 {(_builder.IsBuildManyMethodOverriden ? string.Empty : GenerateBuildManyCode())}
-{(_builder.GenerateStaticPropertyForBuilderCreation ? $"        public static {_builder.FullName} {_entity.Name} => new {_builder.FullName}();" : "")}
+{(_builder.GenerateStaticPropertyForBuilderCreation && !_builder.BuilderConstructorMandatoryParameters ? $"        public static {_builder.FullName} {_entity.Name} => new {_builder.FullName}();" : "")}
 {(_builder.GenerateDefaultBuildMethod ? _entity.GenerateDefaultBuildsCode() : string.Empty)}
 {(_builder.ImplicitCast ? GenerateImplicitCastCode() : string.Empty)}
 {GeneratePreBuildMethod()}

Buildenator/Generators/ConstructorsGenerator.cs

@@ -9,6 +9,60 @@ namespace Buildenator.Generators;
 internal static class ConstructorsGenerator
 {
     internal static string GenerateConstructor(
+        string builderName,
+        IEntityToBuild entity,
+        IFixtureProperties? fixtureConfiguration,
+        bool initializeCollectionsWithEmpty,
+        bool builderConstructorMandatoryParameters)
+    {
+        return builderConstructorMandatoryParameters
+            ? GenerateMandatoryParamConstructor(builderName, entity, initializeCollectionsWithEmpty)
+            : GenerateParameterlessConstructor(builderName, entity, fixtureConfiguration, initializeCollectionsWithEmpty);
+    }
+
+    private static string GenerateMandatoryParamConstructor(
+        string builderName,
+        IEntityToBuild entity,
+        bool initializeCollectionsWithEmpty)
+    {
+        var constructorToBuild = entity.ConstructorToBuild;
+        var mandatoryParams = constructorToBuild?.Parameters.ToList() ?? [];
+
+        var signatureParams = string.Join(", ", mandatoryParams.Select(p => $"{p.TypeFullName} {p.SymbolName}"));
+
+        var output = new StringBuilder();
+        output.AppendLine($@"{CommentsGenerator.GenerateSummaryOverrideComment()}
+        public {builderName}({signatureParams})
+        {{");
+
+        foreach (var p in mandatoryParams)
+        {
+            output.AppendLine($@"            {p.UnderScoreName} = new {DefaultConstants.NullBox}<{p.TypeFullName}>({p.SymbolName});");
+        }
+
+        var settableProperties = entity.AllUniqueSettablePropertiesAndParameters
+            .Where(p => constructorToBuild?.ContainsParameter(p.SymbolPascalName) != true)
+            .ToList();
+
+        if (initializeCollectionsWithEmpty)
+        {
+            foreach (var typedSymbol in settableProperties.Where(ShouldInitializeCollectionField))
+            {
+                var collectionMetadata = typedSymbol.GetCollectionMetadata();
+                if (collectionMetadata != null)
+                {
+                    var initCode = GenerateEmptyCollectionInitialization(typedSymbol, collectionMetadata);
+                    if (!string.IsNullOrEmpty(initCode))
+                        output.AppendLine($@"            {initCode}");
+                }
+            }
+        }
+
+        output.AppendLine($@"        }}");
+        return output.ToString();
+    }
+
+    private static string GenerateParameterlessConstructor(
         string builderName,
         IEntityToBuild entity,
         IFixtureProperties? fixtureConfiguration,

Buildenator/MakeBuilderAttributeInternal.cs

@@ -13,7 +13,8 @@ internal readonly struct MakeBuilderAttributeInternal(
     string? staticFactoryMethodName,
     bool? generateStaticPropertyForBuilderCreation,
     bool? initializeCollectionsWithEmpty,
-    bool? useChildBuilders)
+    bool? useChildBuilders,
+    bool? builderConstructorMandatoryParameters)
 {
 
     public MakeBuilderAttributeInternal(AttributeData attribute)
@@ -29,7 +30,8 @@ attribute.ConstructorArguments[3].Value is null
             (string?)attribute.ConstructorArguments[6].Value,
             (bool?)attribute.ConstructorArguments[7].Value,
             (bool?)attribute.ConstructorArguments[8].Value,
-            (bool?)attribute.ConstructorArguments[9].Value)
+            (bool?)attribute.ConstructorArguments[9].Value,
+            (bool?)attribute.ConstructorArguments[10].Value)
     {
 
     }
@@ -43,5 +45,6 @@ attribute.ConstructorArguments[3].Value is null
     public bool? GenerateStaticPropertyForBuilderCreation { get; } = generateStaticPropertyForBuilderCreation;
     public bool? InitializeCollectionsWithEmpty { get; } = initializeCollectionsWithEmpty;
     public bool? UseChildBuilders { get; } = useChildBuilders;
+    public bool? BuilderConstructorMandatoryParameters { get; } = builderConstructorMandatoryParameters;
     internal string? StaticFactoryMethodName { get; } = staticFactoryMethodName;
 }

CHANGELOG.md

@@ -4,6 +4,39 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## 8.8.0.0 - 2026-3-6
+
+### Added
+- **`builderConstructorMandatoryParameters` option**: New configuration option that makes the generated builder enforce mandatory parameters by requiring the entity's constructor parameters as arguments to the builder's own constructor.
+  - Enabled per builder: `[MakeBuilder(typeof(MyClass), builderConstructorMandatoryParameters: true)]`
+  - Enabled globally: `[assembly: BuildenatorConfiguration(builderConstructorMandatoryParameters: true)]`
+  - When enabled:
+    - The builder gets a **parameterized constructor** mirroring the entity's primary constructor instead of a parameterless one.
+    - The **static factory property** (`generateStaticPropertyForBuilderCreation`) is automatically suppressed, since it would call a parameterless constructor that no longer exists.
+    - All `With...` methods remain available and can still override the values passed to the constructor.
+    - **Mocking is incompatible** — combining this option with a mocking configuration (e.g. `MoqConfiguration`) produces a compile-time error **BDN007**.
+    - **Fixture configuration is incompatible** — combining this option with a fixture configuration (e.g. `AutoFixtureConfiguration`) produces a compile-time error **BDN008**.
+  - Example:
+    ```csharp
+    public class Dto
+    {
+        public Dto(int lineNumber, string activity) { LineNumber = lineNumber; Activity = activity; }
+        public int LineNumber { get; set; }
+        public string Activity { get; set; }
+        public List<string> Tags { get; set; } = [];
+    }
+
+    [MakeBuilder(typeof(Dto), builderConstructorMandatoryParameters: true)]
+    public partial class DtoBuilder { }
+
+    // Usage — constructor enforces required values, With methods allow overrides
+    var dto = new DtoBuilder(lineNumber: 1, activity: "shipping")
+        .AddToTags("express")
+        .Build();
+    ```
+- **BDN007 diagnostic error**: Emitted when `builderConstructorMandatoryParameters = true` is combined with a mocking configuration, since the two features are fundamentally incompatible.
+- **BDN008 diagnostic error**: Emitted when `builderConstructorMandatoryParameters = true` is combined with a fixture configuration, since fixture auto-generation of unset values is incompatible with explicit constructor-driven initialization.
+
 ## 8.7.1.0 - 2025-12-4
 
 ### Fixed