Update to use full test from PR 1292

Xamarin.Forms.Core.UnitTests/BindingBaseUnitTests.cs

@@ -163,9 +163,11 @@ namespace Xamarin.Forms.Core.UnitTests
 			Assert.That (() => binding.StringFormat = "{0}", Throws.InvalidOperationException);
 		}
 
-		[Test]
-		public void StringFormatNonStringType()
+		[TestCase("en-US"), TestCase("tr-TR")]
+		public void StringFormatNonStringType(string culture)
 		{
+			System.Threading.Thread.CurrentThread.CurrentCulture = new System.Globalization.CultureInfo(culture);
+
 			var property = BindableProperty.Create("Foo", typeof(string), typeof(MockBindable));
 			var binding = new Binding("Value", stringFormat: "{0:P2}");