Added generic ObservableValidator.GetErrors return

Author: Sergio0694

Microsoft.Toolkit.Mvvm/ComponentModel/ObservableValidator.cs

@@ -326,14 +326,22 @@ protected bool TrySetProperty<TModel, T>(T oldValue, T newValue, IEqualityCompar
                    SetProperty(oldValue, newValue, comparer, model, callback, propertyName);
         }
 
-        /// <inheritdoc/>
+        /// <inheritdoc cref="INotifyDataErrorInfo.GetErrors(string)"/>
         [Pure]
-        public IEnumerable GetErrors(string? propertyName)
+        public IEnumerable<ValidationResult> GetErrors(string? propertyName)
         {
             // Entity-level errors when the target property is null or empty
             if (string.IsNullOrEmpty(propertyName))
             {
-                return this.GetAllErrors();
+                // Local function to gather all the entity-level errors
+                [Pure]
+                [MethodImpl(MethodImplOptions.NoInlining)]
+                IEnumerable<ValidationResult> GetAllErrors()
+                {
+                    return this.errors.Values.SelectMany(errors => errors);
+                }
+
+                return GetAllErrors();
             }
 
             // Property-level errors, if any
@@ -350,16 +358,9 @@ public IEnumerable GetErrors(string? propertyName)
             return Array.Empty<ValidationResult>();
         }
 
-        /// <summary>
-        /// Implements the logic for entity-level errors gathering for <see cref="GetErrors"/>.
-        /// </summary>
-        /// <returns>An <see cref="IEnumerable"/> instance with all the errors in <see cref="errors"/>.</returns>
+        /// <inheritdoc/>
         [Pure]
-        [MethodImpl(MethodImplOptions.NoInlining)]
-        private IEnumerable GetAllErrors()
-        {
-            return this.errors.Values.SelectMany(errors => errors);
-        }
+        IEnumerable INotifyDataErrorInfo.GetErrors(string? propertyName) => GetErrors(propertyName);
 
         /// <summary>
         /// Validates a property with a specified name and a given input value.

UnitTests/UnitTests.Shared/Mvvm/Test_ObservableValidator.cs

@@ -88,41 +88,41 @@ public void Test_ObservableValidator_GetErrors()
         {
             var model = new Person();
 
-            Assert.AreEqual(model.GetErrors(null).Cast<object>().Count(), 0);
-            Assert.AreEqual(model.GetErrors(string.Empty).Cast<object>().Count(), 0);
-            Assert.AreEqual(model.GetErrors("ThereIsntAPropertyWithThisName").Cast<object>().Count(), 0);
-            Assert.AreEqual(model.GetErrors(nameof(Person.Name)).Cast<object>().Count(), 0);
+            Assert.AreEqual(model.GetErrors(null).Count(), 0);
+            Assert.AreEqual(model.GetErrors(string.Empty).Count(), 0);
+            Assert.AreEqual(model.GetErrors("ThereIsntAPropertyWithThisName").Count(), 0);
+            Assert.AreEqual(model.GetErrors(nameof(Person.Name)).Count(), 0);
 
             model.Name = "Foo";
 
-            var errors = model.GetErrors(nameof(Person.Name)).Cast<ValidationResult>().ToArray();
+            var errors = model.GetErrors(nameof(Person.Name)).ToArray();
 
             Assert.AreEqual(errors.Length, 1);
             Assert.AreEqual(errors[0].MemberNames.First(), nameof(Person.Name));
 
-            Assert.AreEqual(model.GetErrors("ThereIsntAPropertyWithThisName").Cast<object>().Count(), 0);
+            Assert.AreEqual(model.GetErrors("ThereIsntAPropertyWithThisName").Count(), 0);
 
-            errors = model.GetErrors(null).Cast<ValidationResult>().ToArray();
+            errors = model.GetErrors(null).ToArray();
 
             Assert.AreEqual(errors.Length, 1);
             Assert.AreEqual(errors[0].MemberNames.First(), nameof(Person.Name));
 
-            errors = model.GetErrors(string.Empty).Cast<ValidationResult>().ToArray();
+            errors = model.GetErrors(string.Empty).ToArray();
 
             Assert.AreEqual(errors.Length, 1);
             Assert.AreEqual(errors[0].MemberNames.First(), nameof(Person.Name));
 
             model.Age = -1;
 
-            errors = model.GetErrors(null).Cast<ValidationResult>().ToArray();
+            errors = model.GetErrors(null).ToArray();
 
             Assert.AreEqual(errors.Length, 2);
             Assert.IsTrue(errors.Any(e => e.MemberNames.First().Equals(nameof(Person.Name))));
             Assert.IsTrue(errors.Any(e => e.MemberNames.First().Equals(nameof(Person.Age))));
 
             model.Age = 26;
 
-            errors = model.GetErrors(null).Cast<ValidationResult>().ToArray();
+            errors = model.GetErrors(null).ToArray();
 
             Assert.AreEqual(errors.Length, 1);
             Assert.IsTrue(errors.Any(e => e.MemberNames.First().Equals(nameof(Person.Name))));
@@ -145,11 +145,11 @@ public void Test_ObservableValidator_ValidateReturn(string value, bool isValid)
 
             if (isValid)
             {
-                Assert.IsTrue(!model.GetErrors(nameof(Person.Name)).Cast<object>().Any());
+                Assert.IsTrue(!model.GetErrors(nameof(Person.Name)).Any());
             }
             else
             {
-                Assert.IsTrue(model.GetErrors(nameof(Person.Name)).Cast<object>().Any());
+                Assert.IsTrue(model.GetErrors(nameof(Person.Name)).Any());
             }
         }
 
@@ -196,7 +196,7 @@ public void Test_ObservableValidator_TrySetProperty()
             // Errors should now be present
             Assert.IsTrue(model.HasErrors);
             Assert.IsTrue(events.Count == 1);
-            Assert.IsTrue(model.GetErrors(nameof(Person.Name)).Cast<ValidationResult>().Any());
+            Assert.IsTrue(model.GetErrors(nameof(Person.Name)).Any());
             Assert.IsTrue(model.HasErrors);
 
             // Trying to set a correct property should clear the errors