Fix issue with how CascadeMode.Stop works when set inside a child val…

…idator

Changelog.txt

@@ -1,3 +1,6 @@
+11.9.1 - 23 Apr 2024 
+Fix issue with CascadeMode on child validators (#2207)
+
 11.9.0 - 21 Dec 2023
 Fix memory leak in NotEmptyValidator/EmptyValidator (#2174)
 Add more descriptive error messages if a rule throws a NullReferenceException (#2152)

src/Directory.Build.props

@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
-    <VersionPrefix>11.9.0</VersionPrefix>
+    <VersionPrefix>11.9.1</VersionPrefix>
     <VersionSuffix></VersionSuffix>
     <!-- Use CI build number as version suffix (if defined) -->
     <!--<VersionSuffix Condition="'$(GITHUB_RUN_NUMBER)'!=''">ci-$(GITHUB_RUN_NUMBER)</VersionSuffix>-->

src/FluentValidation.Tests/CascadingFailuresTester.cs

@@ -21,6 +21,7 @@
 namespace FluentValidation.Tests;
 
 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using Xunit;
 
@@ -490,6 +491,34 @@ public class CascadingFailuresTester : IDisposable {
 		results.Errors.Count.ShouldEqual(1);
 	}
 
+	[Fact]
+	public async void Cascade_set_to_stop_in_child_validator_with_RuleForEach_in_parent() {
+		// See https://github.com/FluentValidation/FluentValidation/issues/2207
+
+		var childValidator = new InlineValidator<Order>();
+		childValidator.ClassLevelCascadeMode = CascadeMode.Stop;
+		childValidator.RuleFor(x => x.ProductName).NotNull();
+		childValidator.RuleFor(x => x.Amount).GreaterThan(0);
+
+		var parentValidator = new InlineValidator<Person>();
+		parentValidator.RuleForEach(x => x.Orders).SetValidator(childValidator);
+
+		var testData = new List<Order> {
+			// Would cause both rules to fail, but only first rule will be executed because of CascadeMode.Stop
+			new Order { ProductName = null, Amount = 0 },
+
+			// First rule succeeds, second rule fails.
+			new Order { ProductName = "foo", Amount = 0 }
+		};
+
+		// Bug in #2207 meant that the rule for Orders[1].Amount would never execute
+		// as the cascade mode logic was stopping if totalFailures > 0 rather than totalFailures > (count of failures before rule executed)
+		var result = parentValidator.Validate(new Person {Orders = testData});
+		result.Errors.Count.ShouldEqual(2);
+		result.Errors[0].PropertyName.ShouldEqual("Orders[0].ProductName");
+		result.Errors[1].PropertyName.ShouldEqual("Orders[1].Amount");
+	}
+
 	private void SetBothValidatorCascadeModes(CascadeMode cascadeMode) {
 		_validator.ClassLevelCascadeMode = cascadeMode;
 		_validator.RuleLevelCascadeMode = cascadeMode;

src/FluentValidation/AbstractValidator.cs

@@ -241,13 +241,13 @@ ValueTask<ValidationResult> completedValueTask
 		// Performance: Use for loop rather than foreach to reduce allocations.
 		for (int i = 0; i < count; i++) {
 			cancellation.ThrowIfCancellationRequested();
+			var totalFailures = context.Failures.Count;
+
 			await Rules[i].ValidateAsync(context, useAsync, cancellation);
 
-			if (ClassLevelCascadeMode == CascadeMode.Stop && result.Errors.Count > 0) {
-				// Bail out if we're "failing-fast".
-				// Check for > 0 rather than == 1 because a rule chain may have overridden the Stop behaviour to Continue
-				// meaning that although the first rule failed, it actually generated 2 failures if there were 2 validators
-				// in the chain.
+			if (ClassLevelCascadeMode == CascadeMode.Stop && result.Errors.Count > totalFailures) {
+				// Bail out if we're "failing-fast". Check to see if the number of failures
+				// has been increased by this rule (which could've generated 1 or more failures).
 				break;
 			}
 		}