Merge pull request #190 from SteveDunn/disallow-vos-in-non-partial-types

Analyzer should fail build if ValueObject decorated type is not partial

src/Vogen/BuildWorkItems.cs

@@ -35,6 +35,12 @@ internal static class BuildWorkItems
             return null;
         }
 
+        if (!voTypeSyntax.Modifiers.Any(SyntaxKind.PartialKeyword))
+        {
+            context.ReportDiagnostic(DiagnosticItems.TypeShouldBePartial(voTypeSyntax.GetLocation(), voSymbolInformation.Name));
+            return null;
+        }
+
         if (voSymbolInformation.IsAbstract)
         {
             context.ReportDiagnostic(DiagnosticItems.TypeCannotBeAbstract(voSymbolInformation));

src/Vogen/Diagnostics/DiagnosticCode.cs

@@ -26,5 +26,6 @@ public enum DiagnosticCode
     TypeCannotBeAbstract = 17,
     PrimaryConstructorProhibited = 18,
     InvalidCustomizations = 19,
-    RecordToStringOverloadShouldBeSealed = 20
+    RecordToStringOverloadShouldBeSealed = 20,
+    TypeShouldBePartial = 21
 }

src/Vogen/Diagnostics/DiagnosticItems.cs

@@ -38,6 +38,11 @@ internal static class DiagnosticItems
         "Overrides of ToString on records should be sealed to differentiate it from the C# compiler-generated method. See https://github.com/SteveDunn/Vogen/wiki/Records#tostring for more information.",
         "ToString overrides should be sealed on records. See https://github.com/SteveDunn/Vogen/wiki/Records#tostring for more information.");
 
+    private static readonly DiagnosticDescriptor _typeShouldBePartial = CreateDescriptor(
+        DiagnosticCode.TypeShouldBePartial,
+        "Value Objects should be declared in partial types.",
+        "Type {0} is decorated as a Value Object and should be in a partial type.");
+
     private static readonly DiagnosticDescriptor _cannotHaveUserConstructors = CreateDescriptor(
         DiagnosticCode.CannotHaveUserConstructors,
         "Cannot have user defined constructors",
@@ -141,6 +146,9 @@ public static Diagnostic PrimaryConstructorProhibited(Location location, string
     public static Diagnostic RecordToStringOverloadShouldBeSealed(Location location, string voClassName) => 
         BuildDiagnostic(_recordToStringOverloadShouldBeSealed, voClassName, location);
 
+    public static Diagnostic TypeShouldBePartial(Location location, string voClassName) => 
+        BuildDiagnostic(_typeShouldBePartial, voClassName, location);
+
     public static Diagnostic CannotHaveUserConstructors(IMethodSymbol constructor) => 
         Create(_cannotHaveUserConstructors, constructor.Locations);
 

tests/SmallTests/DiagnosticsTests/DisallowNonPartialTests.cs

@@ -0,0 +1,37 @@
+using System.Linq;
+using FluentAssertions;
+using FluentAssertions.Execution;
+using Microsoft.CodeAnalysis;
+using Vogen;
+using Xunit;
+
+namespace SmallTests.DiagnosticsTests;
+
+public class DisallowNonPartialTests
+{
+    [Theory]
+    [InlineData("abstract class")]
+    [InlineData("abstract record class")]
+    public void Disallows_non_partial_types(string type)
+    {
+        var source = $@"using Vogen;
+
+namespace Whatever;
+
+[ValueObject]
+public {type} CustomerId {{ }}
+";
+
+        var (diagnostics, _) = TestHelper.GetGeneratedOutput<ValueObjectGenerator>(source);
+
+        using (new AssertionScope())
+        {
+            diagnostics.Should().HaveCount(1);
+            Diagnostic diagnostic = diagnostics.Single();
+
+            diagnostic.Id.Should().Be("VOG021");
+            diagnostic.ToString().Should()
+                .Match("*: error VOG021: Type CustomerId is decorated as a Value Object and should be in a partial type.");
+        }
+    }
+}

tests/Testbench/Program.cs

@@ -1,22 +1,20 @@
-using System;
-using System.Text.RegularExpressions;
-using Vogen;
+using Vogen;
 
 namespace Whatever
 {
     public class Program
     {
         public static void Main()
         {
-            Console.WriteLine(AccountId.From("xyz").ToString());
+            //Console.WriteLine(AccountId.From("xyz").ToString());
             // To debug the source generator or analyzer, set the active project to Vogen,
             // and then select Roslyn as the debug target. This requires the Roslyn SDK
             // to be installed in the list of Visual Studio components.
         }
     }
 
     [ValueObject(typeof(string))]
-    public partial record AccountId
+    public partial class AccountId
     {
         public override sealed string ToString() => "derived2!";
     }