CNinnovation.Templates.SourceGenerator 2.1.0

MyGenerator — .NET Source Generator Template

This template scaffolds a complete .NET source generator solution that includes:

• MyGenerator/ – The source generator project (netstandard2.0)
• MyGenerator.Tests/ – Unit tests using xUnit v3
• MyGenerator.SnapshotTests/ – Snapshot tests using xUnit v3 + Verify

Using the Template

Install the template from NuGet:

dotnet new install CNinnovation.Templates.SourceGenerator

Scaffold a new generator solution:

dotnet new cni-sourcegen -n AwesomeGenerator
cd AwesomeGenerator

Remove the template installation when no longer needed:

dotnet new uninstall CNinnovation.Templates.SourceGenerator

Project Structure

AwesomeGenerator/
├── AwesomeGenerator/                   # Source generator (netstandard2.0 by default)
│   ├── AwesomeGenerator.csproj
│   └── AwesomeGeneratorImpl.cs         # IIncrementalGenerator implementation
│
├── AwesomeGenerator.Tests/             # xUnit v3 unit tests
│   ├── AwesomeGenerator.Tests.csproj
│   ├── GlobalUsings.cs
│   ├── TestHelper.cs                   # Compiles code and runs the generator
│   └── AwesomeGeneratorTests.cs
│
├── AwesomeGenerator.SnapshotTests/     # xUnit v3 snapshot tests via Verify
│   ├── AwesomeGenerator.SnapshotTests.csproj
│   ├── GlobalUsings.cs
│   ├── TestHelper.cs                   # Runs generator and calls Verifier.Verify
│   ├── AwesomeGeneratorSnapshotTests.cs
│   └── Snapshots/                      # Verified snapshot files live here
│
└── AwesomeGenerator.slnx               # Solution file

Getting Started

Build

dotnet build AwesomeGenerator.slnx

Run Unit Tests

dotnet test AwesomeGenerator.Tests/AwesomeGenerator.Tests.csproj

Run Snapshot Tests

dotnet test AwesomeGenerator.SnapshotTests/AwesomeGenerator.SnapshotTests.csproj

Run All Tests

dotnet test AwesomeGenerator.slnx

How the Generator Works

The template implements a simple but realistic pattern:

1. Inject an attribute – GenerateInfoAttribute is added to every compilation via RegisterPostInitializationOutput.

2. Detect marked classes – one of two approaches is used (selected at scaffold time):

   • CreateSyntaxProvider (default) – visits all class declarations, uses a fast syntactic predicate to filter candidates, then a semantic transform to confirm the attribute is present. Flexible and general-purpose.
   • ForAttributeWithMetadataName – tells Roslyn to watch specifically for [GenerateInfo] by its fully-qualified metadata name. Roslyn only invokes the transform for nodes that already carry the attribute, making it more efficient for attribute-driven generators. Recommended when a single well-known attribute triggers generation.

3. Generate a companion class – For each marked class a <ClassName>Info static class is generated containing compile-time constants (type name, property count, method count) and a GetSummary() method.

Replace GenerateInfoAttribute and the corresponding generation logic in MyGeneratorImpl.cs with your own attribute and code generation.

Choosing a Syntax Provider Mode

# scaffold with the optimized attribute-based approach
dotnet new cni-sourcegen -n AwesomeGenerator -m ForAttributeWithMetadataName

Snapshot Testing with Verify

Snapshot tests use the Verify library together with Verify.SourceGenerators to capture and compare the exact text of every generated source file.

Running the Bundled Snapshot Tests

The template ships with two pre-accepted .verified.txt files in MyGenerator.SnapshotTests/Snapshots/, so the included snapshot tests pass immediately without any extra setup.

First Run for New Tests

When you add a new snapshot test (or modify the generator), no .verified.txt file exists yet for that test. Verify will:

1. Write a .received.txt file in Snapshots/ next to the test class.
2. Fail the test so you can inspect the output.
3. Accept it once the output looks correct (see below).

Accepting / Updating Snapshots

Via environment variable (useful in CI pipelines):

VERIFY_AUTO_APPROVE=true dotnet test AwesomeGenerator.SnapshotTests

Via test runner argument:

dotnet test AwesomeGenerator.SnapshotTests -- Verify.AutoVerify=true

Manually: Rename the .received.txt file to .verified.txt (remove the received segment) and commit it.

Snapshot File Location

Verified snapshots are stored in MyGenerator.SnapshotTests/Snapshots/ and should be committed to source control so that future test runs can detect regressions.

xUnit v3

This template targets xUnit v3 (xunit.v3 NuGet package), which provides:

• Improved parallelism and performance
• Cleaner async test support
• Better extensibility model

All standard xUnit attributes ([Fact], [Theory], [InlineData], etc.) work the same as in xUnit v2.

Customizing the Generator

1. Open MyGeneratorImpl.cs and replace the GenerateInfo attribute name and logic with your own.
2. Update MyGeneratorTests.cs and MyGeneratorSnapshotTests.cs with tests for your new behavior.
3. Run dotnet test to verify everything works.
4. Accept new snapshots as described above.

Requirements

• .NET SDK matching the selected test TFM (for example, net9.0 or net10.0)
• C# 13 (LangVersion latest is set automatically)

Third-Party Dependencies

This template uses the following NuGet packages:

Source Generator

• Microsoft.CodeAnalysis.CSharp (5.0.0) – Roslyn C# compiler API
• Microsoft.CodeAnalysis.Analyzers (4.14.0) – Analyzer development tools

Test Projects

• xUnit v3 (3.2.2) – Unit testing framework
• Microsoft.NET.Test.Sdk (18.3.0) – Test platform
• xunit.runner.visualstudio (3.1.5) – Visual Studio test runner
• coverlet.collector (8.0.0) – Code coverage collector

Snapshot Testing

• Verify.XunitV3 (31.13.2) – Snapshot testing library
• Verify.SourceGenerators (2.5.0) – Source generator snapshot extensions

For complete license information and attribution, see THIRD-PARTY-NOTICES.md.

All dependencies use permissive open-source licenses (MIT or Apache-2.0).