add failing tests for point parsing

tests/Avalonia.Markup.Xaml.UnitTests/Converters/PointsListTypeConverterTests.cs

@@ -7,6 +7,22 @@ namespace Avalonia.Markup.Xaml.UnitTests.Converters
 {
     public class PointsListTypeConverterTests
     {
+        [Theory]
+        [InlineData("1,2 3,4")]
+        [InlineData("1 2 3 4")]
+        [InlineData("1 2,3 4")]
+        [InlineData("1,2,3,4")]
+        public void TypeConverter_Should_Parse(string input)
+        {
+            var conv = new PointsListTypeConverter();
+
+            var points = (IList<Point>)conv.ConvertFrom(input);
+
+            Assert.Equal(2, points.Count);
+            Assert.Equal(new Point(1, 2), points[0]);
+            Assert.Equal(new Point(3, 4), points[1]);
+        }
+
         [Theory]
         [InlineData("1,2 3,4")]
         [InlineData("1 2 3 4")]