handle checked state of radio buttons and checkboxes

src/UglyToad.PdfPig.Tests/Integration/AcroFormsBasicFieldsTests.cs

@@ -2,6 +2,7 @@
 {
     using System;
     using System.Linq;
+    using AcroForms.Fields;
     using Xunit;
 
     public class AcroFormsBasicFieldsTests
@@ -53,5 +54,38 @@
                 Assert.Equal(18, fields.Count);
             }
         }
+
+        [Fact]
+        public void GetsRadioButtonState()
+        {
+            using (var document = PdfDocument.Open(GetFilename(), ParsingOptions.LenientParsingOff))
+            {
+                var form = document.GetForm();
+                var radioButtons = form.Fields.OfType<AcroRadioButtonsField>().ToList();
+
+                Assert.Equal(2, radioButtons.Count);
+
+                // ReSharper disable once PossibleInvalidOperationException
+                var ordered = radioButtons.OrderBy(x => x.Children.Min(y => y.Bounds.Value.Left)).ToList();
+
+                var left = ordered[0];
+
+                Assert.Equal(2, left.Children.Count);
+                foreach (var acroFieldBase in left.Children)
+                {
+                    var button = Assert.IsType<AcroRadioButtonField>(acroFieldBase);
+                    Assert.False(button.IsSelected);
+                }
+
+                var right = ordered[1];
+                Assert.Equal(2, right.Children.Count);
+
+                var buttonOn = Assert.IsType<AcroRadioButtonField>(right.Children[0]);
+                Assert.True(buttonOn.IsSelected);
+
+                var buttonOff = Assert.IsType<AcroRadioButtonField>(right.Children[1]);
+                Assert.False(buttonOff.IsSelected);
+            }
+        }
     }
 }