Fixes mandatory validation issue when creating a new document and a mandatory language has validation problems

src/Umbraco.Tests/Web/ModelStateExtensionsTests.cs

@@ -12,6 +12,31 @@ namespace Umbraco.Tests.Web
     public class ModelStateExtensionsTests
     {
 
+        [Test]
+        public void Get_Cultures_With_Errors()
+        {
+            var ms = new ModelStateDictionary();
+            var localizationService = new Mock<ILocalizationService>();
+            localizationService.Setup(x => x.GetDefaultLanguageIsoCode()).Returns("en-US");
+
+            ms.AddPropertyError(new ValidationResult("no header image"), "headerImage", null); //invariant property
+            ms.AddPropertyError(new ValidationResult("title missing"), "title", "en-US"); //variant property
+
+            var result = ms.GetCulturesWithErrors(localizationService.Object);
+
+            //even though there are 2 errors, they are both for en-US since that is the default language and one of the errors is for an invariant property
+            Assert.AreEqual(1, result.Count);
+            Assert.AreEqual("en-US", result[0]);
+
+            ms = new ModelStateDictionary();
+            ms.AddCultureValidationError("en-US", "generic culture error");
+
+            result = ms.GetCulturesWithErrors(localizationService.Object);
+
+            Assert.AreEqual(1, result.Count);
+            Assert.AreEqual("en-US", result[0]);
+        }
+
         [Test]
         public void Get_Cultures_With_Property_Errors()
         {