Merge pull request #582 from SteveDunn/581-stj-guid-exception

The System.Text.JsonConverter now throws a JsonException

src/Vogen/Templates/Guid/Guid_SystemTextJsonConverter.cs

@@ -3,18 +3,23 @@ class VOTYPESystemTextJsonConverter : global::System.Text.Json.Serialization.Jso
         {
             public override VOTYPE Read(ref global::System.Text.Json.Utf8JsonReader reader, global::System.Type typeToConvert, global::System.Text.Json.JsonSerializerOptions options)
             {
-                return VOTYPE.Deserialize(System.Guid.Parse(reader.GetString()));
+                return VOTYPE.Deserialize(reader.GetGuid());
             }
 
             public override void Write(System.Text.Json.Utf8JsonWriter writer, VOTYPE value, global::System.Text.Json.JsonSerializerOptions options)
             {
                 writer.WriteStringValue(value.Value);
             }
 
-#if NET6_0_OR_GREATER
+#if NET6_0_OR_GREATER // we can't call Read or use GetGuid from JsonReader as it expects a token type of string, but here we have have 'propertyname'.
             public override VOTYPE ReadAsPropertyName(ref global::System.Text.Json.Utf8JsonReader reader, global::System.Type typeToConvert, global::System.Text.Json.JsonSerializerOptions options)
             {
-                return VOTYPE.Deserialize(System.Guid.Parse(reader.GetString()));
+                if (global::System.Guid.TryParse(reader.GetString(), out global::System.Guid g))
+                {
+                    return VOTYPE.Deserialize(g);
+                }
+
+                throw new global::System.Text.Json.JsonException("Unable to parse the GUID for an instance of VOTYPE");
             }
 
             public override void WriteAsPropertyName(System.Text.Json.Utf8JsonWriter writer, VOTYPE value, global::System.Text.Json.JsonSerializerOptions options)

tests/ConsumerTests/BugFixTests/BugFix581.cs

@@ -0,0 +1,34 @@
+using System.Text.Json;
+
+namespace ConsumerTests.BugFixTests.BugFix581;
+
+public class ObjectContainerForVo
+{
+    public required ObjectType Ot { get; set; }
+}
+
+[ValueObject<Guid>(Conversions.Default)]
+public readonly partial struct ObjectType
+{
+}
+
+/// <summary>
+/// Fixes bug https://github.com/SteveDunn/Vogen/issues/581 where GUIDs that are deserialized
+/// with null, throw a NullReferenceException instead of System.Text.JsonException.
+/// </summary>
+public class Tests
+{
+    [Fact]
+    public void Should_throw_Stj_exception_with_null_passed()
+    {
+        Action a = () => JsonSerializer.Deserialize<ObjectContainerForVo>("""{"Ot":null}""");
+        a.Should().ThrowExactly<JsonException>().WithMessage("The JSON value could not be converted to ConsumerTests.BugFixTests.BugFix581.ObjectType. Path: $.Ot | LineNumber: 0 | BytePositionInLine: 10.");
+    }
+
+    [Fact]
+    public void Should_throw_Stj_exception_with_invalid_guid_passed()
+    {
+        Action a = () => JsonSerializer.Deserialize<ObjectContainerForVo>("""{"Ot":"Trevor woz ere"}""");
+        a.Should().ThrowExactly<JsonException>().WithMessage("The JSON value could not be converted to ConsumerTests.BugFixTests.BugFix581.ObjectType. Path: $.Ot | LineNumber: 0 | BytePositionInLine: 22.");
+    }
+}

tests/SnapshotTests/BugFixes/Bug581_StjDeserializer_throws_correct_exception.cs

@@ -0,0 +1,43 @@
+using System.Threading.Tasks;
+using Shared;
+using VerifyXunit;
+using Vogen;
+
+namespace SnapshotTests.BugFixes;
+
+// See https://github.com/SteveDunn/Vogen/issues/581
+[UsesVerify]
+public class Bug581_StjDeserializer_throws_correct_exception
+{
+    // The System.Text.Json converter called Guid.Parse, which in turn threw a NullReferenceException.
+    // It should now use Guid.TryParse and return an STJ exception.
+    // This test just verifies that the correct code is generated. The consumer tests verify the runtime
+    // behaviour.
+    [Fact]
+    public async Task Test()
+    {
+        var source = """
+
+                     using System;
+                     using Vogen;
+                     using System.Text.Json;
+                     
+                     [ValueObject(typeof(Guid))]
+                     public partial struct Vo
+                     {
+                     }
+                     
+                     
+                     """;
+
+        await RunTest(source);
+    }
+
+
+    private static Task RunTest(string source) =>
+        new SnapshotRunner<ValueObjectGenerator>()
+            .WithSource(source)
+            .IgnoreInitialCompilationErrors()
+            .RunOnAllFrameworks();
+
+}