When there is a default constructor, then do not call a constructor

Author: Colin Wilmans

src/SourceDepend.Tests/SourceDependTests.cs

@@ -413,6 +413,67 @@ public ExampleService(IAnotherService anotherService, string someString) : base(
         Assert.Equal(expec, actual.Item2);
     }
 
+    [Fact]
+    public void SourceDepend_WithBaseWithConstructorWithParametersAndParameterless_ShouldNotCallABaseConstructor()
+    {
+        //Arrange
+        var source = """
+                     public partial class ExampleService : BaseService
+                     {
+
+                         [Dependency]
+                         private readonly IAnotherService anotherService;
+                     }
+
+                     public partial class BaseService
+                     {
+                         private readonly string _someString;
+                         public BaseService(string someString)
+                         {
+                            _someString = someString;
+                         }
+
+                         public BaseService()
+                         {
+
+                         }
+                     }
+
+                     public interface IAnotherService {}
+                     """;
+
+        var expec = """
+                     // <auto-generated/>
+                     #pragma warning disable
+                     #nullable enable
+                     /// <inheritdoc/>
+                     public partial class ExampleService
+                     {
+                         public ExampleService(IAnotherService anotherService)
+                         {
+                    
+                     #if NET6_0_OR_GREATER
+                             ArgumentNullException.ThrowIfNull(anotherService);
+                     #endif
+                             PreConstruct();
+
+                             this.anotherService = anotherService;
+
+                             PostConstruct();
+                         }
+                     
+                         partial void PreConstruct();
+                         partial void PostConstruct();
+                     }
+
+                     """;
+        //Act
+        var actual = SourceCompiler.GetGeneratedOutput(source, _output);
+
+        //Assert
+        Assert.Equal(expec, actual.Item2);
+    }
+
     [Fact]
     public void SourceDepend_WithBaseWithDependencyAttributes_ShouldRepeatTheseAndCallThisBaseConstructor()
     {

src/SourceDepend/Extensions/DependentClassExtensions.cs

@@ -3,6 +3,7 @@
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using SourceDepend.Model;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 
 namespace SourceDepend.Extensions;
@@ -62,14 +63,24 @@ internal static class DependentClassExtensions
                     }
                 }
 
-                //Check the first constructor
-                if (baseSymbols == null && classSymbol.BaseType.Constructors.Length > 0)
+                //OK, next best: Check whether there is a default constructor, or otherwise take the first constructor
+                if (baseSymbols is null)
                 {
-                    var constructor = classSymbol.BaseType.Constructors[0];
-                    if (constructor.Parameters.Length > 0)
+                    ImmutableArray<IParameterSymbol>? parameters = null;
+                    foreach (var constructor in classSymbol.BaseType.Constructors)
                     {
-                        baseSymbols = constructor.Parameters.Cast<ISymbol>().ToList();
+                        if (constructor.Parameters.Length == 0)
+                        {
+                            goto has_default_constructor;
+                        }
+                        parameters ??= constructor.Parameters;
+                    }
+
+                    if (parameters is not null)
+                    {
+                        baseSymbols = parameters.Cast<ISymbol>().ToList();
                     }
+                    has_default_constructor:;
                 }
             }
 

src/SourceDepend/SourceDepend.csproj

@@ -36,7 +36,7 @@
             <PrivateAssets>all</PrivateAssets>
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
         </PackageReference>
-        <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.8.0" />
+        <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.10.0" />
     </ItemGroup>
 </Project>