Support deserialization with System.Text.Json

src/FluentValidation.Tests/JsonSerializationTests.cs

@@ -0,0 +1,35 @@
+namespace FluentValidation.Tests;
+
+using System.Text.Json;
+using Results;
+using Xunit;
+
+public class JsonSerializationTests {
+
+	[Fact]
+	public void SystemTextJson_deserialization_should_be_consistent_with_newtonsoft() {
+		var validationResult = new ValidationResult {
+			Errors = {
+				new ValidationFailure("MyProperty1", "Invalid MyProperty1"),
+				new ValidationFailure("MyProperty2", "Invalid MyProperty2"),
+				new ValidationFailure("MyProperty3", "Invalid MyProperty3")
+			}
+		};
+		// System.Text.Json
+		var serialized1 = JsonSerializer.Serialize(validationResult);
+		var deserialized1 = JsonSerializer.Deserialize<ValidationResult>(serialized1);
+
+		// Newtonsoft.Json
+		var serialized2 = Newtonsoft.Json.JsonConvert.SerializeObject(validationResult);
+		var deserialized2 = Newtonsoft.Json.JsonConvert.DeserializeObject<ValidationResult>(serialized2);
+
+		Assert.NotNull(deserialized1);
+		Assert.Equal(deserialized1.IsValid, deserialized2.IsValid);
+		Assert.Equal(deserialized1.Errors.Count, deserialized2.Errors.Count);
+
+		for (var i = 0; i < deserialized1.Errors.Count; i++) {
+			Assert.Equal(deserialized1.Errors[i].PropertyName, deserialized2.Errors[i].PropertyName);
+			Assert.Equal(deserialized1.Errors[i].ErrorMessage, deserialized2.Errors[i].ErrorMessage);
+		}
+	}
+}

src/FluentValidation/Results/ValidationFailure.cs

@@ -25,7 +25,8 @@ namespace FluentValidation.Results {
 	/// </summary>
 	[Serializable]
 	public class ValidationFailure {
-		private ValidationFailure() {
+
+		public ValidationFailure() {
 
 		}
 

src/FluentValidation/Results/ValidationResult.cs

@@ -26,7 +26,7 @@ namespace FluentValidation.Results {
 	/// </summary>
 	[Serializable]
 	public class ValidationResult {
-		private readonly List<ValidationFailure> _errors;
+		private List<ValidationFailure> _errors;
 
 		/// <summary>
 		/// Whether validation succeeded
@@ -36,7 +36,14 @@ public class ValidationResult {
 		/// <summary>
 		/// A collection of errors
 		/// </summary>
-		public List<ValidationFailure> Errors => _errors;
+		public List<ValidationFailure> Errors {
+			get => _errors;
+#if NETSTANDARD2_0_OR_GREATER
+			set => _errors = value ?? throw new ArgumentNullException(nameof(value));
+#else
+			init => _errors = value ?? throw new ArgumentNullException(nameof(value));
+#endif
+		}
 
 		public string[] RuleSetsExecuted { get; internal set; }