refactor: Add snapshot tests using Verify.SourceGenerators

.gitattributes

@@ -12,5 +12,9 @@
 *.fsproj
 *.dbproj
 
+# Verify snapshot files
+*.verified.txt text eol=lf working-tree-encoding=UTF-8
+*.verified.cs  text eol=lf working-tree-encoding=UTF-8
+
 # Don't check for trailing whitespace at end of lines in the doc pages
 *.md -whitespace=blank-at-eol

.gitignore

@@ -9,6 +9,9 @@
 # SourceGenerator Launch Settings
 src/CompositeKey.SourceGeneration/Properties/launchSettings.json
 
+# Verify snapshot testing
+*.received.*
+
 # Claude Code
 .claude/settings.local.json
 .claude/todos/

CLAUDE.md

@@ -63,6 +63,14 @@ The solution is split into four main projects plus corresponding test projects:
 
 - Commit messages follow Conventional Commits (`feat:`, `fix:`, `perf:`, etc.) — GitVersion and `.versionrc` drive versioning and changelog
 - EditorConfig: 4-space indent, UTF-8, LF line endings, 120-char max line length
-- Test stack: xunit + Shouldly + AutoFixture
+- Test stack: xunit + Shouldly + AutoFixture + Verify (snapshot testing)
 - Unit tests use `CompilationHelper` to create in-memory Roslyn compilations
 - Functional tests define real key types and test format/parse round-trips
+- Snapshot tests (`Snapshots/` in `SourceGeneration.UnitTests`) use
+  Verify.SourceGenerators to capture generated `.g.cs` output and
+  `GenerationSpec` models as `.verified.*` baselines — any change to
+  emitted code or parser output will cause a snapshot diff failure
+- `*.received.*` files are gitignored; only `*.verified.*` baselines
+  are committed
+- The `ModuleInitializer` scrubs the non-deterministic
+  `GeneratedCodeAttribute` version string to keep snapshots stable

src/CompositeKey.SourceGeneration.UnitTests/CompositeKey.SourceGeneration.UnitTests.csproj

@@ -15,6 +15,8 @@
 
     <ItemGroup>
         <PackageReference Include="Microsoft.CodeAnalysis" />
+        <PackageReference Include="Verify.SourceGenerators" />
+        <PackageReference Include="Verify.Xunit" />
     </ItemGroup>
 
     <ItemGroup>

src/CompositeKey.SourceGeneration.UnitTests/ModuleInitializer.cs

@@ -0,0 +1,24 @@
+using System.Runtime.CompilerServices;
+using System.Text.RegularExpressions;
+using VerifyXunit;
+
+namespace CompositeKey.SourceGeneration.UnitTests;
+
+public static class ModuleInitializer
+{
+    [ModuleInitializer]
+    public static void Init()
+    {
+        VerifySourceGenerators.Initialize();
+
+        // Scrub the non-deterministic informational version (includes git commit hash)
+        // from the GeneratedCodeAttribute emitted by the source generator.
+        // e.g. [GeneratedCodeAttribute("CompositeKey.SourceGeneration", "1.6.0+7675481fa523...")]
+        //   -> [GeneratedCodeAttribute("CompositeKey.SourceGeneration", "VERSION")]
+        VerifierSettings.ScrubLinesWithReplace(line =>
+            Regex.Replace(
+                line,
+                @"GeneratedCodeAttribute\(""CompositeKey\.SourceGeneration"", ""[^""]*""\)",
+                @"GeneratedCodeAttribute(""CompositeKey.SourceGeneration"", ""VERSION"")"));
+    }
+}

src/CompositeKey.SourceGeneration.UnitTests/Snapshots/SourceGeneratorSnapshotTests.BasicCompositePrimaryKey_GenerationSpec.verified.txt

@@ -0,0 +1,298 @@
+[
+  {
+    TargetType: {
+      Type: {
+        Name: BasicPrimaryKey,
+        FullyQualifiedName: global::UnitTests.BasicPrimaryKey
+      },
+      Namespace: UnitTests,
+      TypeDeclarations: [
+        public partial record BasicPrimaryKey
+      ],
+      Properties: [
+        {
+          Type: {
+            Name: Guid,
+            FullyQualifiedName: global::System.Guid
+          },
+          Name: FirstPart,
+          CamelCaseName: firstPart,
+          IsRequired: false,
+          HasGetter: true,
+          HasSetter: true,
+          IsInitOnlySetter: true
+        },
+        {
+          Type: {
+            Name: String,
+            FullyQualifiedName: string
+          },
+          Name: SecondPart,
+          CamelCaseName: secondPart,
+          IsRequired: false,
+          HasGetter: true,
+          HasSetter: true,
+          IsInitOnlySetter: true
+        },
+        {
+          Type: {
+            Name: CustomEnum,
+            FullyQualifiedName: global::UnitTests.CustomEnum
+          },
+          Name: ThirdPart,
+          CamelCaseName: thirdPart,
+          IsRequired: false,
+          HasGetter: true,
+          HasSetter: true,
+          IsInitOnlySetter: true,
+          EnumSpec: {
+            Name: CustomEnum,
+            FullyQualifiedName: global::UnitTests.CustomEnum,
+            UnderlyingType: int,
+            Members: [
+              {
+                Name: One,
+                Value: 0
+              },
+              {
+                Name: Two,
+                Value: 1
+              },
+              {
+                Name: Three,
+                Value: 2
+              }
+            ],
+            IsSequentialFromZero: true
+          }
+        }
+      ],
+      ConstructorParameters: [
+        {
+          Type: {
+            Name: Guid,
+            FullyQualifiedName: global::System.Guid
+          },
+          Name: FirstPart,
+          CamelCaseName: firstPart
+        },
+        {
+          Type: {
+            Name: String,
+            FullyQualifiedName: string
+          },
+          Name: SecondPart,
+          CamelCaseName: secondPart,
+          ParameterIndex: 1
+        },
+        {
+          Type: {
+            Name: CustomEnum,
+            FullyQualifiedName: global::UnitTests.CustomEnum
+          },
+          Name: ThirdPart,
+          CamelCaseName: thirdPart,
+          ParameterIndex: 2
+        }
+      ],
+      TypeName: BasicPrimaryKey
+    },
+    Key: {
+      AllParts: [
+        {
+          Property: {
+            Type: {
+              Name: Guid,
+              FullyQualifiedName: global::System.Guid
+            },
+            Name: FirstPart,
+            CamelCaseName: firstPart,
+            IsRequired: false,
+            HasGetter: true,
+            HasSetter: true,
+            IsInitOnlySetter: true
+          },
+          Format: b,
+          LengthRequired: 38,
+          ExactLengthRequirement: true
+        },
+        {
+          Value: #,
+          LengthRequired: 1,
+          ExactLengthRequirement: true
+        },
+        {
+          Property: {
+            Type: {
+              Name: String,
+              FullyQualifiedName: string
+            },
+            Name: SecondPart,
+            CamelCaseName: secondPart,
+            IsRequired: false,
+            HasGetter: true,
+            HasSetter: true,
+            IsInitOnlySetter: true
+          },
+          ParseType: String,
+          FormatType: String,
+          LengthRequired: 1,
+          ExactLengthRequirement: false
+        },
+        {
+          Value: |,
+          LengthRequired: 1,
+          ExactLengthRequirement: true
+        },
+        {
+          Value: ConstantValue,
+          LengthRequired: 13,
+          ExactLengthRequirement: true
+        },
+        {
+          Value: #,
+          LengthRequired: 1,
+          ExactLengthRequirement: true
+        },
+        {
+          Property: {
+            Type: {
+              Name: CustomEnum,
+              FullyQualifiedName: global::UnitTests.CustomEnum
+            },
+            Name: ThirdPart,
+            CamelCaseName: thirdPart,
+            IsRequired: false,
+            HasGetter: true,
+            HasSetter: true,
+            IsInitOnlySetter: true,
+            EnumSpec: {
+              Name: CustomEnum,
+              FullyQualifiedName: global::UnitTests.CustomEnum,
+              UnderlyingType: int,
+              Members: [
+                {
+                  Name: One,
+                  Value: 0
+                },
+                {
+                  Name: Two,
+                  Value: 1
+                },
+                {
+                  Name: Three,
+                  Value: 2
+                }
+              ],
+              IsSequentialFromZero: true
+            }
+          },
+          Format: g,
+          ParseType: Enum,
+          FormatType: Enum,
+          LengthRequired: 1,
+          ExactLengthRequirement: false
+        }
+      ],
+      PartitionKeyParts: [
+        {
+          Property: {
+            Type: {
+              Name: Guid,
+              FullyQualifiedName: global::System.Guid
+            },
+            Name: FirstPart,
+            CamelCaseName: firstPart,
+            IsRequired: false,
+            HasGetter: true,
+            HasSetter: true,
+            IsInitOnlySetter: true
+          },
+          Format: b,
+          LengthRequired: 38,
+          ExactLengthRequirement: true
+        },
+        {
+          Value: #,
+          LengthRequired: 1,
+          ExactLengthRequirement: true
+        },
+        {
+          Property: {
+            Type: {
+              Name: String,
+              FullyQualifiedName: string
+            },
+            Name: SecondPart,
+            CamelCaseName: secondPart,
+            IsRequired: false,
+            HasGetter: true,
+            HasSetter: true,
+            IsInitOnlySetter: true
+          },
+          ParseType: String,
+          FormatType: String,
+          LengthRequired: 1,
+          ExactLengthRequirement: false
+        }
+      ],
+      PrimaryDelimiterKeyPart: {
+        Value: |,
+        LengthRequired: 1,
+        ExactLengthRequirement: true
+      },
+      SortKeyParts: [
+        {
+          Value: ConstantValue,
+          LengthRequired: 13,
+          ExactLengthRequirement: true
+        },
+        {
+          Value: #,
+          LengthRequired: 1,
+          ExactLengthRequirement: true
+        },
+        {
+          Property: {
+            Type: {
+              Name: CustomEnum,
+              FullyQualifiedName: global::UnitTests.CustomEnum
+            },
+            Name: ThirdPart,
+            CamelCaseName: thirdPart,
+            IsRequired: false,
+            HasGetter: true,
+            HasSetter: true,
+            IsInitOnlySetter: true,
+            EnumSpec: {
+              Name: CustomEnum,
+              FullyQualifiedName: global::UnitTests.CustomEnum,
+              UnderlyingType: int,
+              Members: [
+                {
+                  Name: One,
+                  Value: 0
+                },
+                {
+                  Name: Two,
+                  Value: 1
+                },
+                {
+                  Name: Three,
+                  Value: 2
+                }
+              ],
+              IsSequentialFromZero: true
+            }
+          },
+          Format: g,
+          ParseType: Enum,
+          FormatType: Enum,
+          LengthRequired: 1,
+          ExactLengthRequirement: false
+        }
+      ],
+      InvariantFormatting: true
+    }
+  }
+]