ci: add build-and-test workflow with smoke test

Adds .github/workflows/ci.yml running on push to main and PRs.
Builds the analyzer and runs two xUnit smoke tests that instantiate
CodeGraphWalker against trivial C# sources and assert graph output.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: TheSmallPixel

.github/workflows/ci.yml

@@ -0,0 +1,26 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  build-and-test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '8.0.x'
+
+      - name: Build analyzer
+        run: dotnet build --configuration Release tools/CodeAnalysisTool/CodeAnalysisTool.csproj
+
+      - name: Build tests
+        run: dotnet build --configuration Release tools/CodeAnalysisTool.Tests/CodeAnalysisTool.Tests.csproj
+
+      - name: Run tests
+        run: dotnet test --configuration Release --no-build --logger "console;verbosity=normal" tools/CodeAnalysisTool.Tests/CodeAnalysisTool.Tests.csproj

tools/CodeAnalysisTool.Tests/CodeAnalysisTool.Tests.csproj

@@ -0,0 +1,20 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <IsPackable>false</IsPackable>
+    <Nullable>enable</Nullable>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
+    <PackageReference Include="xunit" Version="2.9.2" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\CodeAnalysisTool\CodeAnalysisTool.csproj" />
+  </ItemGroup>
+
+</Project>

tools/CodeAnalysisTool.Tests/WalkerSmokeTests.cs

@@ -0,0 +1,71 @@
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Xunit;
+
+namespace CodeAnalysisTool.Tests;
+
+public class WalkerSmokeTests
+{
+    [Fact]
+    public void Walker_emits_namespace_class_and_method_nodes_for_trivial_source()
+    {
+        const string source = @"
+namespace Demo
+{
+    public class Greeter
+    {
+        public string Hello(string name) => $""hi {name}"";
+    }
+}";
+
+        var tree = CSharpSyntaxTree.ParseText(source);
+        var compilation = CSharpCompilation.Create(
+            "Smoke",
+            new[] { tree },
+            new[] { MetadataReference.CreateFromFile(typeof(object).Assembly.Location) });
+
+        var walker = new CodeGraphWalker
+        {
+            SemanticModel = compilation.GetSemanticModel(tree)
+        };
+        walker.SetCurrentFile("Greeter.cs");
+        walker.Visit(tree.GetRoot());
+
+        var graph = walker.GetGraph();
+
+        Assert.NotEmpty(graph.Nodes);
+        Assert.Contains(graph.Nodes, n => n.Group == "namespace");
+        Assert.Contains(graph.Nodes, n => n.Group == "class");
+        Assert.Contains(graph.Nodes, n => n.Group == "method");
+    }
+
+    [Fact]
+    public void Walker_emits_links_between_namespace_and_class()
+    {
+        const string source = @"
+namespace MyApp
+{
+    public class Service
+    {
+        public void Run() { }
+    }
+}";
+
+        var tree = CSharpSyntaxTree.ParseText(source);
+        var compilation = CSharpCompilation.Create(
+            "Links",
+            new[] { tree },
+            new[] { MetadataReference.CreateFromFile(typeof(object).Assembly.Location) });
+
+        var walker = new CodeGraphWalker
+        {
+            SemanticModel = compilation.GetSemanticModel(tree)
+        };
+        walker.SetCurrentFile("Service.cs");
+        walker.Visit(tree.GetRoot());
+
+        var graph = walker.GetGraph();
+
+        Assert.NotEmpty(graph.Links);
+    }
+}