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feat: Add generator for StubAttribute
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‎src/bunit.generators/README.md‎

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# bUnit Generators
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This package contains source generators for bUnit, to make it easier and more convenient to write tests.
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This package contains source generators for bUnit, to make it easier and more convenient to write tests.
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## `AddStub` Generator
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This generator adds the ability to automatically generate stubs for a given type. This comes in handy, when dealing
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with 3rd party components that might need an extensive setup. Here a small example:
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This generator adds the ability to automatically generate stubs for a given type with no setup involved. The generator sits on top of the already
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present `AddStub` method.
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This comes in handy, when dealing with 3rd party components that might need an extensive setup. Here a small example:
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Given the following component
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```razor
@@ -49,6 +50,31 @@ To use the generator, the **Interceptor** feature has to be used inside the cspr
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<InterceptorsPreviewNamespaces>$(InterceptorsPreviewNamespaces);Bunit</InterceptorsPreviewNamespaces>
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```
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This limits the usage to .NET 8 and above.
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## `StubAttribute`
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This generator adds the ability to automatically generate stubs for a given type via an attribute.
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The general setup for the given component above looks like this:
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```csharp
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namespace MyTest;
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public class FeatureTests : TestContext
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{
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[Fact]
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public void Test()
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{
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ComponentFactories.Add<ThirdPartyText, ThirdPartyStub>();
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...
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}
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}
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[Stub(typeof(ThirdPartyText))]
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internal partial class ThidPartyStub { }
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```
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Current limitations of this approach:
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* The stubbed type is not allowed to be nested inside the test class.
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## Developer notes
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### Tips for developing with the generator
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dotnet build-server shutdown
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```
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A good way to quicky see if the generate is producing output:
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A good way to quickly see if the generate is producing output:
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```
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dotnet build-server shutdown && dotnet clean && dotnet test -p:TargetFramework=net8.0

src/bunit.generators/Web.Stubs/StubGenerator.cs renamed to src/bunit.generators/Web.Stubs/AddStubMethodStubGenerator/AddStubGenerator.cs

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@@ -6,17 +6,14 @@
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using Microsoft.CodeAnalysis;
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using Microsoft.CodeAnalysis.CSharp.Syntax;
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namespace Bunit.Web.Stubs;
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namespace Bunit.Web.Stubs.AddStubMethodStubGenerator;
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/// <summary>
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/// Generator that creates a stub that mimics the public surface of a Component.
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/// </summary>
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[Generator]
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public class StubGenerator : IIncrementalGenerator
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public class AddStubGenerator : IIncrementalGenerator
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{
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private const string CascadingParameterAttributeQualifier = "Microsoft.AspNetCore.Components.CascadingParameterAttribute";
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private const string ParameterAttributeQualifier = "Microsoft.AspNetCore.Components.ParameterAttribute";
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/// <inheritdoc/>
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public void Initialize(IncrementalGeneratorInitializationContext context)
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{
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static (spc, source) => Execute(source, spc));
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}
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private static StubClassInfo GetStubClassInfo(GeneratorSyntaxContext context)
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private static AddStubClassInfo GetStubClassInfo(GeneratorSyntaxContext context)
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{
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var invocation = context.Node as InvocationExpressionSyntax;
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if (!IsComponentFactoryStubMethod(invocation, context.SemanticModel))
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var line = lineSpan.StartLinePosition.Line + 1;
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var column = lineSpan.Span.Start.Character + context.Node.ToString().IndexOf("AddStub", StringComparison.Ordinal) + 1;
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return new StubClassInfo
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return new AddStubClassInfo
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{
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StubClassName = $"{symbol.Name}Stub",
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TargetTypeNamespace = symbol.ContainingNamespace.ToDisplayString(),
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}
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}
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private static void Execute(ImmutableArray<StubClassInfo> classInfos, SourceProductionContext context)
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private static void Execute(ImmutableArray<AddStubClassInfo> classInfos, SourceProductionContext context)
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{
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foreach (var stubClassGrouped in classInfos.GroupBy(c => c.UniqueQualifier))
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{
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var stubbedComponentGroup = stubClassGrouped.First();
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var didStubComponent = GenerateStubComponent(stubbedComponentGroup, context);
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var didStubComponent = StubComponentBuilder.GenerateStubComponent(stubbedComponentGroup, context);
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if (didStubComponent is false)
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{
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return;
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}
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}
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104-
private static bool GenerateStubComponent(StubClassInfo classInfo, SourceProductionContext context)
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{
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var hasSomethingToStub = false;
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var targetTypeSymbol = (INamedTypeSymbol)classInfo!.TargetType;
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var sourceBuilder = new StringBuilder();
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sourceBuilder.AppendLine($"namespace {classInfo.TargetTypeNamespace};");
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sourceBuilder.AppendLine();
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sourceBuilder.AppendLine($"internal partial class {classInfo.StubClassName} : global::Microsoft.AspNetCore.Components.ComponentBase");
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sourceBuilder.Append("{");
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foreach (var member in targetTypeSymbol
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.GetMembers()
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.OfType<IPropertySymbol>()
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.Where(p => p.GetAttributes()
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.Any(attr =>
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attr.AttributeClass?.ToDisplayString() ==
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ParameterAttributeQualifier ||
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attr.AttributeClass?.ToDisplayString() ==
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CascadingParameterAttributeQualifier)))
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{
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sourceBuilder.AppendLine();
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hasSomethingToStub = true;
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var propertyType = member.Type.ToDisplayString();
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var propertyName = member.Name;
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var attributeLine = GetAttributeLine(member);
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sourceBuilder.AppendLine(attributeLine);
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sourceBuilder.AppendLine($"\tpublic {propertyType} {propertyName} {{ get; set; }}");
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}
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sourceBuilder.AppendLine("}");
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if (hasSomethingToStub)
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{
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context.AddSource($"{classInfo.StubClassName}.g.cs", sourceBuilder.ToString());
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}
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return hasSomethingToStub;
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string GetAttributeLine(ISymbol member)
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{
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var attribute = member.GetAttributes().First(attr =>
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attr.AttributeClass?.ToDisplayString() == ParameterAttributeQualifier ||
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attr.AttributeClass?.ToDisplayString() == CascadingParameterAttributeQualifier);
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var attributeLine = new StringBuilder("\t[");
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if (attribute.AttributeClass?.ToDisplayString() == ParameterAttributeQualifier)
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{
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attributeLine.Append($"global::{ParameterAttributeQualifier}");
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var captureUnmatchedValuesArg = attribute.NamedArguments
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.FirstOrDefault(arg => arg.Key == "CaptureUnmatchedValues").Value;
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if (captureUnmatchedValuesArg.Value is bool captureUnmatchedValues)
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{
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var captureString = captureUnmatchedValues ? "true" : "false";
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attributeLine.Append($"(CaptureUnmatchedValues = {captureString})");
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}
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}
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else if (attribute.AttributeClass?.ToDisplayString() == CascadingParameterAttributeQualifier)
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{
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attributeLine.Append($"global::{CascadingParameterAttributeQualifier}");
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var nameArg = attribute.NamedArguments.FirstOrDefault(arg => arg.Key == "Name").Value;
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if (!nameArg.IsNull)
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{
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attributeLine.Append($"(Name = \"{nameArg.Value}\")");
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}
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}
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174-
attributeLine.Append("]");
175-
return attributeLine.ToString();
176-
}
177-
}
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179-
private static void GenerateInterceptorCode(StubClassInfo stubbedComponentGroup, IEnumerable<StubClassInfo> stubClassGrouped, SourceProductionContext context)
103+
private static void GenerateInterceptorCode(AddStubClassInfo stubbedComponentGroup, IEnumerable<AddStubClassInfo> stubClassGrouped, SourceProductionContext context)
180104
{
181105
// Generate the attribute
182106
const string attribute = @"namespace System.Runtime.CompilerServices
@@ -222,7 +146,7 @@ public InterceptsLocationAttribute(string filePath, int line, int column)
222146
}
223147
}
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225-
internal sealed class StubClassInfo
149+
internal sealed class AddStubClassInfo
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{
227151
public string StubClassName { get; set; }
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public string TargetTypeNamespace { get; set; }

‎src/bunit.generators/Web.Stubs/AddStubMethodStubGenerator/StubComponentBuilder.cs‎

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using System.Linq;
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using System.Text;
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using Microsoft.CodeAnalysis;
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namespace Bunit.Web.Stubs.AddStubMethodStubGenerator;
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7+
internal static class StubComponentBuilder
8+
{
9+
private const string CascadingParameterAttributeQualifier = "Microsoft.AspNetCore.Components.CascadingParameterAttribute";
10+
private const string ParameterAttributeQualifier = "Microsoft.AspNetCore.Components.ParameterAttribute";
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12+
public static bool GenerateStubComponent(AddStubClassInfo classInfo, SourceProductionContext context)
13+
{
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var hasSomethingToStub = false;
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var targetTypeSymbol = (INamedTypeSymbol)classInfo!.TargetType;
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var sourceBuilder = new StringBuilder();
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18+
sourceBuilder.AppendLine($"namespace {classInfo.TargetTypeNamespace};");
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sourceBuilder.AppendLine();
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sourceBuilder.AppendLine($"internal partial class {classInfo.StubClassName} : global::Microsoft.AspNetCore.Components.ComponentBase");
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sourceBuilder.Append("{");
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23+
foreach (var member in targetTypeSymbol
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.GetMembers()
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.OfType<IPropertySymbol>()
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.Where(p => p.GetAttributes()
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.Any(attr =>
28+
attr.AttributeClass?.ToDisplayString() ==
29+
ParameterAttributeQualifier ||
30+
attr.AttributeClass?.ToDisplayString() ==
31+
CascadingParameterAttributeQualifier)))
32+
{
33+
sourceBuilder.AppendLine();
34+
35+
hasSomethingToStub = true;
36+
var propertyType = member.Type.ToDisplayString();
37+
var propertyName = member.Name;
38+
39+
var attributeLine = GetAttributeLine(member);
40+
sourceBuilder.AppendLine(attributeLine);
41+
42+
sourceBuilder.AppendLine($"\tpublic {propertyType} {propertyName} {{ get; set; }}");
43+
}
44+
45+
sourceBuilder.AppendLine("}");
46+
47+
if (hasSomethingToStub)
48+
{
49+
context.AddSource($"{classInfo.StubClassName}.g.cs", sourceBuilder.ToString());
50+
}
51+
52+
return hasSomethingToStub;
53+
54+
string GetAttributeLine(ISymbol member)
55+
{
56+
var attribute = member.GetAttributes().First(attr =>
57+
attr.AttributeClass?.ToDisplayString() == ParameterAttributeQualifier ||
58+
attr.AttributeClass?.ToDisplayString() == CascadingParameterAttributeQualifier);
59+
60+
var attributeLine = new StringBuilder("\t[");
61+
if (attribute.AttributeClass?.ToDisplayString() == ParameterAttributeQualifier)
62+
{
63+
attributeLine.Append($"global::{ParameterAttributeQualifier}");
64+
var captureUnmatchedValuesArg = attribute.NamedArguments
65+
.FirstOrDefault(arg => arg.Key == "CaptureUnmatchedValues").Value;
66+
if (captureUnmatchedValuesArg.Value is bool captureUnmatchedValues)
67+
{
68+
var captureString = captureUnmatchedValues ? "true" : "false";
69+
attributeLine.Append($"(CaptureUnmatchedValues = {captureString})");
70+
}
71+
}
72+
else if (attribute.AttributeClass?.ToDisplayString() == CascadingParameterAttributeQualifier)
73+
{
74+
attributeLine.Append($"global::{CascadingParameterAttributeQualifier}");
75+
var nameArg = attribute.NamedArguments.FirstOrDefault(arg => arg.Key == "Name").Value;
76+
if (!nameArg.IsNull)
77+
{
78+
attributeLine.Append($"(Name = \"{nameArg.Value}\")");
79+
}
80+
}
81+
82+
attributeLine.Append("]");
83+
return attributeLine.ToString();
84+
}
85+
}
86+
}

‎src/bunit.generators/Web.Stubs/AttributeStubGenerator/StubAttribute.cs‎

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namespace Bunit.Web.Stubs.AttributeStubGenerator;
2+
3+
internal static class StubAttribute
4+
{
5+
public static string StubAttributeSource = @"#if NET5_0_OR_GREATER
6+
namespace Bunit;
7+
8+
/// <summary>
9+
/// Indicates that the component will be enriched by a generated class.
10+
/// </summary>
11+
[global::System.AttributeUsage(global::System.AttributeTargets.Class, Inherited = false)]
12+
internal sealed class StubAttribute : global::System.Attribute
13+
{
14+
/// <summary>
15+
/// The target type of the component the stub represents.
16+
/// </summary>
17+
public global::System.Type TargetType { get; }
18+
19+
/// <summary>
20+
/// Creates an instance of the <see cref=""StubAttribute""/>.
21+
/// </summary>
22+
/// <param name=""targetType"">The target type of the component the stub represents.</param>
23+
public StubAttribute(global::System.Type targetType)
24+
{
25+
TargetType = targetType;
26+
}
27+
}
28+
#endif";
29+
}

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