diff --git a/VisitorPatternGenerator.Tests/BaseSourceGeneratorTestContainer.cs b/VisitorPatternGenerator.Tests/BaseSourceGeneratorTestContainer.cs
new file mode 100644
index 0000000..ffbfbe1
--- /dev/null
+++ b/VisitorPatternGenerator.Tests/BaseSourceGeneratorTestContainer.cs
@@ -0,0 +1,15 @@
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.Testing.Verifiers;
+
+using RoseLynn.Testing;
+
+using VisitorPatternGenerator.Tests.Verifiers;
+
+namespace VisitorPatternGenerator.Tests;
+
+public abstract class BaseSourceGeneratorTestContainer<TGenerator>: BaseIncrementalGeneratorTestContainer<TGenerator, NUnitVerifier, CSharpSourceGeneratorVerifier<TGenerator>.Test>
+    where TGenerator : IIncrementalGenerator, new()
+{
+    protected override LanguageVersion LanguageVersion => LanguageVersion.CSharp11;
+}
diff --git a/VisitorPatternGenerator.Tests/RuntimeReferences.cs b/VisitorPatternGenerator.Tests/RuntimeReferences.cs
new file mode 100644
index 0000000..7bcac5a
--- /dev/null
+++ b/VisitorPatternGenerator.Tests/RuntimeReferences.cs
@@ -0,0 +1,15 @@
+using System.IO;
+
+using Microsoft.CodeAnalysis.Testing;
+
+namespace VisitorPatternGenerator.Tests;
+
+public static class RuntimeReferences
+{
+    public static readonly ReferenceAssemblies NET7_0Reference =
+        new(
+            "net7.0",
+            new PackageIdentity(
+                "Microsoft.NETCore.App.Ref", "7.0.0"),
+                Path.Combine("ref", "net7.0"));
+}
diff --git a/VisitorPatternGenerator.Tests/UnitTest1.cs b/VisitorPatternGenerator.Tests/UnitTest1.cs
deleted file mode 100644
index bf9eea0..0000000
--- a/VisitorPatternGenerator.Tests/UnitTest1.cs
+++ /dev/null
@@ -1,12 +0,0 @@
-using Xunit;
-
-namespace VisitorPatternGenerator.Tests;
-
-public class UnitTest1
-{
-    [Fact]
-    public void Test1()
-    {
-
-    }
-}
diff --git a/VisitorPatternGenerator.Tests/Verifiers/CSharpSourceGeneratorVerifier.cs b/VisitorPatternGenerator.Tests/Verifiers/CSharpSourceGeneratorVerifier.cs
new file mode 100644
index 0000000..8bdf2d6
--- /dev/null
+++ b/VisitorPatternGenerator.Tests/Verifiers/CSharpSourceGeneratorVerifier.cs
@@ -0,0 +1,18 @@
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Testing.Verifiers;
+
+using RoseLynn.Testing;
+
+namespace VisitorPatternGenerator.Tests.Verifiers;
+
+public static class CSharpSourceGeneratorVerifier<TGenerator>
+    where TGenerator : IIncrementalGenerator, new()
+{
+    public class Test: CSharpIncrementalGeneratorTestEx<TGenerator, NUnitVerifier>
+    {
+        public Test()
+        {
+            this.ReferenceAssemblies = RuntimeReferences.NET7_0Reference;
+        }
+    }
+}
diff --git a/VisitorPatternGenerator.Tests/VisitorPatternGenerator.Tests.csproj b/VisitorPatternGenerator.Tests/VisitorPatternGenerator.Tests.csproj
index 3d58fed..95bbe3c 100644
--- a/VisitorPatternGenerator.Tests/VisitorPatternGenerator.Tests.csproj
+++ b/VisitorPatternGenerator.Tests/VisitorPatternGenerator.Tests.csproj
@@ -1,8 +1,9 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net7.0</TargetFramework>
     <RootNamespace>$(MSBuildProjectName)</RootNamespace>
+    <IsPackable>false</IsPackable>
   </PropertyGroup>
 
   <ItemGroup>
@@ -10,23 +11,30 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="MessagePack.Annotations" Version="2.4.59" />
+    <PackageReference Include="NUnit" Version="3.13.3" />
+    <PackageReference Include="NUnit3TestAdapter" Version="4.4.2" />
+    <PackageReference Include="MessagePack.Annotations" Version="2.5.108" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.5.0" />
-    <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="3.2.0">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
+    
+    <PackageReference Include="RoseLynn.Testing" Version="0.6.4" />
+
+    <PackageReference Include="Microsoft.CodeAnalysis.Analyzer.Testing" Version="1.1.1" />
+
+    <PackageReference Include="Microsoft.CodeAnalysis" Version="4.5.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.Common" Version="4.5.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.5.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.SourceGenerators.Testing.NUnit" Version="1.1.1" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.5.0" />
   </ItemGroup>
 
   <ItemGroup>
     <ProjectReference Include="..\VisitorPatternGenerator\VisitorPatternGenerator.csproj">
       <OutputItemType>Analyzer</OutputItemType>
-      <ReferenceOutputAssembly>fales</ReferenceOutputAssembly>
+      <ReferenceOutputAssembly>true</ReferenceOutputAssembly>
     </ProjectReference>
   </ItemGroup>
 
diff --git a/VisitorPatternGenerator.Tests/VisitorPatternGeneratorTests.cs b/VisitorPatternGenerator.Tests/VisitorPatternGeneratorTests.cs
new file mode 100644
index 0000000..dd8441e
--- /dev/null
+++ b/VisitorPatternGenerator.Tests/VisitorPatternGeneratorTests.cs
@@ -0,0 +1,311 @@
+using NUnit.Framework;
+
+namespace VisitorPatternGenerator.Tests;
+
+public sealed class VisitorPatternGeneratorTests: BaseSourceGeneratorTestContainer<VisitorPatternGenerator>
+{
+    [Test]
+    public void SimpleCase()
+    {
+        var source = """
+            using VisitorPatternGenerator;
+
+            namespace SurgicalThing.Tools;
+
+            public struct Unit { }
+
+            public interface ITool
+            {
+                bool IsAvailable { get; }
+                bool IsDisabled { get; set; }
+            }
+
+            public abstract class Tool : ITool
+            {
+                public bool IsDisabled { get; set; }
+
+                public virtual bool IsAvailable => !IsDisabled;
+            }
+
+            public interface IConsumableTool : ITool
+            {
+                double CurrentDurability { get; set; }
+                double MaxDurability { get; set; }
+
+                void ResetDurability();
+            }
+
+            public abstract class ConsumableTool : Tool, IConsumableTool
+            {
+                public double CurrentDurability { get; set; }
+                public double MaxDurability { get; set; }
+
+                public override bool IsAvailable => CurrentDurability > 0 && base.IsAvailable;
+
+                protected ConsumableTool(double maxDurability)
+                {
+                    MaxDurability = maxDurability;
+                    CurrentDurability = maxDurability;
+                }
+
+                public void ResetDurability()
+                {
+                    CurrentDurability = MaxDurability;
+                }
+            }
+
+            public partial interface IMedication : IConsumableTool { }
+
+            [Acceptor<IMedication>]
+            public abstract partial class Medication : ConsumableTool
+            {
+                protected Medication(double maxDurability)
+                    : base(maxDurability) { }
+            }
+
+            public partial interface IGeneralMedication { }
+
+            [Acceptor<IMedication>]
+            [Acceptor<IGeneralMedication>]
+            public abstract partial class GeneralMedication : Medication
+            {
+                protected GeneralMedication(double maxDurability)
+                    : base(maxDurability) { }
+            }
+            public partial interface ISpecializedMedication { }
+
+            [Acceptor<IMedication>]
+            [Acceptor<ISpecializedMedication>]
+            public abstract partial class SpecializedMedication : Medication
+            {
+                protected SpecializedMedication(double maxDurability)
+                    : base(maxDurability) { }
+            }
+
+            [Acceptor<IMedication>]
+            [Acceptor<IGeneralMedication>]
+            public sealed partial class Stabilizer : GeneralMedication
+            {
+                public Stabilizer(double maxDurability)
+                    : base(maxDurability) { }
+            }
+
+            // Visitors
+            [Visitor<IMedication, Unit>]
+            public partial interface IGeneratedMedicationVisitor { }
+            [Visitor<IGeneralMedication, Unit>]
+            public partial interface IGeneratedGeneralMedicationVisitor { }
+            [Visitor<ISpecializedMedication, Unit>]
+            public partial interface IGeneratedSpecializedMedicationVisitor { }
+            [Visitor<ITool, Unit>]
+            public partial interface IGeneratedToolVisitor { }
+            """;
+
+        var annotationsTemplate = """
+            // <auto-generated/>
+            #nullable enable
+
+            namespace VisitorPatternGenerator;
+
+            [System.Flags]
+            internal enum AcceptorOptions
+            {
+                None = 0,
+                MessagePackUnion = 0x100,
+            }
+
+            [System.Diagnostics.Conditional("VISITOR_PATTERN_GENERATOR_PRESERVE_ANNOTATION")]
+            [System.AttributeUsage(System.AttributeTargets.Interface | System.AttributeTargets.Class, AllowMultiple = false, Inherited = false)]
+            internal sealed class AcceptorAttribute: System.Attribute
+            {
+                public AcceptorOptions Options { get; }
+
+                public AcceptorAttribute(AcceptorOptions options = AcceptorOptions.None) { this.Options = options; }
+            }
+
+            [System.Diagnostics.Conditional("VISITOR_PATTERN_GENERATOR_PRESERVE_ANNOTATION")]
+            [System.AttributeUsage(System.AttributeTargets.Class, AllowMultiple = true, Inherited = false)]
+            internal sealed class AcceptorAttribute<TAcceptor>: System.Attribute where TAcceptor : class { }
+
+            [System.Diagnostics.Conditional("VISITOR_PATTERN_GENERATOR_PRESERVE_ANNOTATION")]
+            [System.AttributeUsage(System.AttributeTargets.Class, AllowMultiple = true, Inherited = false)]
+            internal sealed class AcceptorAttribute<TAcceptor, TSelf>: System.Attribute where TAcceptor : class where TSelf : class { }
+
+            [System.Diagnostics.Conditional("VISITOR_PATTERN_GENERATOR_PRESERVE_ANNOTATION")]
+            [System.AttributeUsage(System.AttributeTargets.Class, AllowMultiple = true, Inherited = false)]
+            internal sealed class AcceptorAttribute<TAcceptor, TSelf, TResult>: System.Attribute where TAcceptor : class where TSelf : class { }
+
+            [System.Diagnostics.Conditional("VISITOR_PATTERN_GENERATOR_PRESERVE_ANNOTATION")]
+            [System.AttributeUsage(System.AttributeTargets.Interface, AllowMultiple = false, Inherited = false)]
+            internal sealed class VisitorAttribute<TAcceptor>: System.Attribute where TAcceptor : class
+            {
+                public bool VoidReturn { get; }
+
+                public VisitorAttribute(bool voidReturn = false) { this.VoidReturn = voidReturn; }
+            }
+
+            [System.Diagnostics.Conditional("VISITOR_PATTERN_GENERATOR_PRESERVE_ANNOTATION")]
+            [System.AttributeUsage(System.AttributeTargets.Interface, AllowMultiple = false, Inherited = false)]
+            internal sealed class VisitorAttribute<TAcceptor, TResult>: System.Attribute where TAcceptor : class { }
+
+            [System.Diagnostics.Conditional("VISITOR_PATTERN_GENERATOR_PRESERVE_ANNOTATION")]
+            [System.AttributeUsage(System.AttributeTargets.Interface, AllowMultiple = false, Inherited = false)]
+            internal sealed class TaskVisitorAttribute<TAcceptor>: System.Attribute where TAcceptor : class
+            {
+                public bool VoidReturn { get; }
+
+                public TaskVisitorAttribute(bool voidReturn = false) { this.VoidReturn = voidReturn; }
+            }
+
+            [System.Diagnostics.Conditional("VISITOR_PATTERN_GENERATOR_PRESERVE_ANNOTATION")]
+            [System.AttributeUsage(System.AttributeTargets.Interface, AllowMultiple = false, Inherited = false)]
+            internal sealed class TaskVisitorAttribute<TAcceptor, TResult>: System.Attribute where TAcceptor : class { }
+
+            [System.Diagnostics.Conditional("VISITOR_PATTERN_GENERATOR_PRESERVE_ANNOTATION")]
+            [System.AttributeUsage(System.AttributeTargets.Interface, AllowMultiple = false, Inherited = false)]
+            internal sealed class ValueTaskVisitorAttribute<TAcceptor>: System.Attribute where TAcceptor : class
+            {
+                public bool VoidReturn { get; }
+
+                public ValueTaskVisitorAttribute(bool voidReturn = false) { this.VoidReturn = voidReturn; }
+            }
+
+            [System.Diagnostics.Conditional("VISITOR_PATTERN_GENERATOR_PRESERVE_ANNOTATION")]
+            [System.AttributeUsage(System.AttributeTargets.Interface, AllowMultiple = false, Inherited = false)]
+            internal sealed class ValueTaskVisitorAttribute<TAcceptor, TResult>: System.Attribute where TAcceptor : class { }
+
+
+            """;
+
+        var generatedMedicineVisitor = """
+            // <auto-generated/>
+
+            namespace SurgicalThing.Tools
+            {
+            partial interface IMedication
+            {
+                SurgicalThing.Tools.Unit Accept(SurgicalThing.Tools.IGeneratedMedicationVisitor visitor);
+            }
+            }
+
+            namespace SurgicalThing.Tools
+            {
+            partial interface IGeneratedMedicationVisitor
+            {
+                SurgicalThing.Tools.Unit Visit(SurgicalThing.Tools.Medication value);
+                SurgicalThing.Tools.Unit Visit(SurgicalThing.Tools.GeneralMedication value);
+                SurgicalThing.Tools.Unit Visit(SurgicalThing.Tools.SpecializedMedication value);
+                SurgicalThing.Tools.Unit Visit(SurgicalThing.Tools.Stabilizer value);
+            }
+            }
+
+            namespace SurgicalThing.Tools
+            {
+            partial class Medication: SurgicalThing.Tools.IMedication
+            {
+                SurgicalThing.Tools.Unit SurgicalThing.Tools.IMedication.Accept(SurgicalThing.Tools.IGeneratedMedicationVisitor visitor) => visitor.Visit(this);
+            }
+            }
+
+            namespace SurgicalThing.Tools
+            {
+            partial class GeneralMedication: SurgicalThing.Tools.IMedication
+            {
+                SurgicalThing.Tools.Unit SurgicalThing.Tools.IMedication.Accept(SurgicalThing.Tools.IGeneratedMedicationVisitor visitor) => visitor.Visit(this);
+            }
+            }
+
+            namespace SurgicalThing.Tools
+            {
+            partial class SpecializedMedication: SurgicalThing.Tools.IMedication
+            {
+                SurgicalThing.Tools.Unit SurgicalThing.Tools.IMedication.Accept(SurgicalThing.Tools.IGeneratedMedicationVisitor visitor) => visitor.Visit(this);
+            }
+            }
+
+            namespace SurgicalThing.Tools
+            {
+            partial class Stabilizer: SurgicalThing.Tools.IMedication
+            {
+                SurgicalThing.Tools.Unit SurgicalThing.Tools.IMedication.Accept(SurgicalThing.Tools.IGeneratedMedicationVisitor visitor) => visitor.Visit(this);
+            }
+            }
+            
+            """;
+        var generatedGeneralMedicationVisitor = """
+            // <auto-generated/>
+
+            namespace SurgicalThing.Tools
+            {
+            partial interface IGeneralMedication
+            {
+                SurgicalThing.Tools.Unit Accept(SurgicalThing.Tools.IGeneratedGeneralMedicationVisitor visitor);
+            }
+            }
+
+            namespace SurgicalThing.Tools
+            {
+            partial interface IGeneratedGeneralMedicationVisitor
+            {
+                SurgicalThing.Tools.Unit Visit(SurgicalThing.Tools.GeneralMedication value);
+                SurgicalThing.Tools.Unit Visit(SurgicalThing.Tools.Stabilizer value);
+            }
+            }
+
+            namespace SurgicalThing.Tools
+            {
+            partial class GeneralMedication: SurgicalThing.Tools.IGeneralMedication
+            {
+                SurgicalThing.Tools.Unit SurgicalThing.Tools.IGeneralMedication.Accept(SurgicalThing.Tools.IGeneratedGeneralMedicationVisitor visitor) => visitor.Visit(this);
+            }
+            }
+
+            namespace SurgicalThing.Tools
+            {
+            partial class Stabilizer: SurgicalThing.Tools.IGeneralMedication
+            {
+                SurgicalThing.Tools.Unit SurgicalThing.Tools.IGeneralMedication.Accept(SurgicalThing.Tools.IGeneratedGeneralMedicationVisitor visitor) => visitor.Visit(this);
+            }
+            }
+            
+            """;
+        var generatedSpecializedMedicationVisitor = """
+            // <auto-generated/>
+
+            namespace SurgicalThing.Tools
+            {
+            partial interface ISpecializedMedication
+            {
+                SurgicalThing.Tools.Unit Accept(SurgicalThing.Tools.IGeneratedSpecializedMedicationVisitor visitor);
+            }
+            }
+
+            namespace SurgicalThing.Tools
+            {
+            partial interface IGeneratedSpecializedMedicationVisitor
+            {
+                SurgicalThing.Tools.Unit Visit(SurgicalThing.Tools.SpecializedMedication value);
+            }
+            }
+
+            namespace SurgicalThing.Tools
+            {
+            partial class SpecializedMedication: SurgicalThing.Tools.ISpecializedMedication
+            {
+                SurgicalThing.Tools.Unit SurgicalThing.Tools.ISpecializedMedication.Accept(SurgicalThing.Tools.IGeneratedSpecializedMedicationVisitor visitor) => visitor.Visit(this);
+            }
+            }
+            
+            """;
+
+        var mappings = new (string fileName, string source)[] {
+            ("AnnotationsTemplate.cs", annotationsTemplate),
+
+            ("SurgicalThing.Tools.IGeneratedMedicationVisitor.cs", generatedMedicineVisitor),
+            ("SurgicalThing.Tools.IGeneratedGeneralMedicationVisitor.cs", generatedGeneralMedicationVisitor),
+            ("SurgicalThing.Tools.IGeneratedSpecializedMedicationVisitor.cs", generatedSpecializedMedicationVisitor),
+        };
+
+        this.VerifyAsync(source, mappings, default).Wait();
+    }
+}
diff --git a/VisitorPatternGenerator/VisitorPatternGenerator.cs b/VisitorPatternGenerator/VisitorPatternGenerator.cs
index 8e43116..21fb626 100644
--- a/VisitorPatternGenerator/VisitorPatternGenerator.cs
+++ b/VisitorPatternGenerator/VisitorPatternGenerator.cs
@@ -1,4 +1,3 @@
-using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Linq;
@@ -82,6 +81,11 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
             context.RegisterSourceOutput(visitorProvider, static (ctx, e) => {
                 var ((visitor, acceptors), rootNamespace) = e;
                 ctx.CancellationToken.ThrowIfCancellationRequested();
+
+                if (acceptors.IsDefaultOrEmpty) {
+                    return;
+                }
+
                 _AddVisitorSource(ctx, rootNamespace, visitor, acceptors);
             });
         }