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Refactor PropertyResolverGenerator to handle nullable properties and update tests for resolver generation #2

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Merged
tombiddulph merged 1 commit into from
Feb 6, 2026
Merged

Refactor PropertyResolverGenerator to handle nullable properties and update tests for resolver generation #2

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49 changes: 30 additions & 19 deletions src/PropertyResolvers.Generators/PropertyResolverGenerator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -99,19 +99,17 @@ private static ImmutableArray<ResolverConfig> GetResolverConfigs(Compilation com
switch (namedArg.Key)
{
case "IncludeNamespaces":
config.IncludeNamespaces = namedArg.Value.Values
config.IncludeNamespaces = [.. namedArg.Value.Values
.Select(v => v.Value as string)
.Where(v => v != null)
.Cast<string>()
.ToArray();
.Cast<string>()];
break;

case "ExcludeNamespaces":
config.ExcludeNamespaces = namedArg.Value.Values
config.ExcludeNamespaces = [.. namedArg.Value.Values
.Select(v => v.Value as string)
.Where(v => v != null)
.Cast<string>()
.ToArray();
.Cast<string>()];
break;

}
Expand Down Expand Up @@ -139,13 +137,13 @@ private static void CollectTypes(INamespaceSymbol ns, List<TypeInfo> types)
{
continue;
}

if (type.TypeKind is TypeKind.Class or TypeKind.Struct)
if (type is {TypeKind: TypeKind.Class or TypeKind.Struct, DeclaredAccessibility: Accessibility.Public})
{
var properties = type.GetMembers()
.OfType<IPropertySymbol>()
.Where(p => p.DeclaredAccessibility == Accessibility.Public && p.GetMethod != null)
.Select(p => new PropertyInfo(p.Name))
.Select(p => new PropertyInfo(p.Name, IsNullableProperty(p)))
.ToImmutableArray();

if (properties.Length > 0)
Expand Down Expand Up @@ -183,7 +181,7 @@ private static void CollectNestedTypes(INamedTypeSymbol type, List<TypeInfo> typ
var properties = type.GetMembers()
.OfType<IPropertySymbol>()
.Where(p => p.DeclaredAccessibility == Accessibility.Public && p.GetMethod != null)
.Select(p => new PropertyInfo(p.Name))
.Select(p => new PropertyInfo(p.Name, IsNullableProperty(p)))
.ToImmutableArray();

if (properties.Length > 0)
Expand Down Expand Up @@ -238,7 +236,7 @@ private static void GenerateResolvers(
.Where(t => ShouldIncludeType(t, config))
.SelectMany(t => t.Properties
.Where(p => p.Name.Equals(config.PropertyName, StringComparison.OrdinalIgnoreCase))
.Select(p => (TypeFullName: t.FullName, PropertyName: p.Name)))
.Select(p => (TypeFullName: t.FullName, PropertyName: p.Name, p.IsNullable)))
.ToList();

if (matches.Count == 0)
Expand All @@ -253,21 +251,17 @@ private static void GenerateResolvers(
methods.AppendLine(" {");


foreach (var (typeName, propertyName) in matches)
foreach (var (typeName, propertyName, isNullable) in matches)
{
methods.AppendLine($" global::{typeName} x => x.{propertyName}.ToString(),");
var toStringCall = isNullable ? "?.ToString()" : ".ToString()";
methods.AppendLine($" global::{typeName} x => x.{propertyName}{toStringCall},");
}

methods.AppendLine(" _ => null");
methods.AppendLine(" };");
methods.AppendLine();
}

if (methods.Length == 0)
{
continue;
}

var code = $$"""
// <auto-generated/>
#nullable enable
Expand All @@ -284,6 +278,23 @@ public static class {{className}}
}
}

private static bool IsNullableProperty(IPropertySymbol property)
{
// Nullable value type (e.g., int?, Guid?)
if (property.Type.OriginalDefinition.SpecialType == SpecialType.System_Nullable_T)
{
return true;
}

// Nullable reference type (e.g., string?, object?)
if (property.NullableAnnotation == NullableAnnotation.Annotated)
{
return true;
}

return false;
}

private static bool ShouldIncludeType(TypeInfo type, ResolverConfig config)
{
var ns = type.Namespace;
Expand Down Expand Up @@ -317,7 +328,7 @@ private sealed class ResolverConfig
public string ResolverClassName => $"{PropertyName}Resolver";
}

private record struct PropertyInfo(string Name);
private record struct PropertyInfo(string Name, bool IsNullable);

private record struct TypeInfo(string FullName, string Namespace, ImmutableArray<PropertyInfo> Properties);
}
106 changes: 101 additions & 5 deletions tests/PropertyResolvers.Tests/PropertyResolverGeneratorTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -191,7 +191,7 @@ public class Customer
}

[Fact]
public void GeneratorWithNoMatchingTypesDoesNotGenerateResolver()
public void GeneratorWithNoMatchingTypesGeneratesEmptyResolver()
{
const string source = """

Expand All @@ -213,7 +213,11 @@ public class Order
var generatedFile = result.GeneratedTrees
.FirstOrDefault(t => t.FilePath.EndsWith("NonExistentPropertyResolver.g.cs", StringComparison.Ordinal));

Assert.Null(generatedFile);
Assert.NotNull(generatedFile);

var generatedCode = generatedFile.GetText().ToString();
Assert.Contains("public static class NonExistentPropertyResolver", generatedCode);
Assert.DoesNotContain("public static string?", generatedCode);
}

[Fact]
Expand Down Expand Up @@ -414,7 +418,7 @@ public class NonGenericEntity
}

[Fact]
public void GeneratorWithOnlyGenericTypesGeneratesNoResolver()
public void GeneratorWithOnlyGenericTypesGeneratesEmptyResolver()
{
const string source = """

Expand All @@ -438,10 +442,102 @@ public class AnotherGeneric<TKey, TValue>

var result = RunGenerator(source);

// No resolver should be generated since all matching types are generic
var generatedFile = result.GeneratedTrees
.FirstOrDefault(t => t.FilePath.EndsWith("AccountIdResolver.g.cs", StringComparison.Ordinal));

Assert.Null(generatedFile);
Assert.NotNull(generatedFile);

var generatedCode = generatedFile.GetText().ToString();
Assert.Contains("public static class AccountIdResolver", generatedCode);
Assert.DoesNotContain("public static string?", generatedCode);
}

[Fact]
public void GeneratorWithNullableReferenceTypeUsesNullConditional()
{
const string source = """

#nullable enable
using PropertyResolvers.Attributes;

[assembly: GeneratePropertyResolver("AccountId")]

namespace TestNamespace
{
public class Order
{
public string? AccountId { get; set; }
}
}
""";

var result = RunGenerator(source);

var generatedFile = result.GeneratedTrees
.FirstOrDefault(t => t.FilePath.EndsWith("AccountIdResolver.g.cs", StringComparison.Ordinal));

Assert.NotNull(generatedFile);

var generatedCode = generatedFile.GetText().ToString();
Assert.Contains("x.AccountId?.ToString()", generatedCode);
}

[Fact]
public void GeneratorWithNullableValueTypeUsesNullConditional()
{
const string source = """

using PropertyResolvers.Attributes;

[assembly: GeneratePropertyResolver("Amount")]

namespace TestNamespace
{
public class Order
{
public int? Amount { get; set; }
}
}
""";

var result = RunGenerator(source);

var generatedFile = result.GeneratedTrees
.FirstOrDefault(t => t.FilePath.EndsWith("AmountResolver.g.cs", StringComparison.Ordinal));

Assert.NotNull(generatedFile);

var generatedCode = generatedFile.GetText().ToString();
Assert.Contains("x.Amount?.ToString()", generatedCode);
}

[Fact]
public void GeneratorWithNonNullableTypeUsesToString()
{
const string source = """

using PropertyResolvers.Attributes;

[assembly: GeneratePropertyResolver("AccountId")]

namespace TestNamespace
{
public class Order
{
public string AccountId { get; set; }
}
}
""";

var result = RunGenerator(source);

var generatedFile = result.GeneratedTrees
.FirstOrDefault(t => t.FilePath.EndsWith("AccountIdResolver.g.cs", StringComparison.Ordinal));

Assert.NotNull(generatedFile);

var generatedCode = generatedFile.GetText().ToString();
Assert.Contains("x.AccountId.ToString()", generatedCode);
Assert.DoesNotContain("x.AccountId?.ToString()", generatedCode);
}
}