Fix possible exception in SetBackingField for empty properties.

Author: tom-englert

AssemblyToProcess/WithInterceptors.cs

@@ -31,6 +31,57 @@ private void SetInterceptor(object value, string propertyName)
     public string Property2 { get; set; }
 }
 
+public class ClassWithReadonlyProperty
+{
+    private int _field = 42;
+
+    [GetInterceptor]
+    private object GetInterceptor(string propertyName, Type propertyType)
+    {
+        return Convert.ChangeType(_field, propertyType);
+    }
+
+    [SetInterceptor]
+    private void SetInterceptor(object value, string propertyName)
+    {
+        _field = Convert.ToInt32(value);
+    }
+
+    public int Property1 { get; set; }
+
+    public string Property2 { get; set; }
+
+    public string Property3 { get; }
+}
+
+public abstract class ClassWithAbstractProperty
+{
+    private int _field = 42;
+
+    [GetInterceptor]
+    protected object GetInterceptor(string propertyName, Type propertyType)
+    {
+        return Convert.ChangeType(_field, propertyType);
+    }
+
+    [SetInterceptor]
+    protected void SetInterceptor(object value, string propertyName)
+    {
+        _field = Convert.ToInt32(value);
+    }
+
+    public abstract int Property1 { get; set; }
+
+    public abstract string Property2 { get; set; }
+}
+
+public class ClassDerivedFromClassWithAbstractProperty : ClassWithAbstractProperty
+{
+    public override int Property1 { get; set; }
+
+    public override string Property2 { get; set; }
+}
+
 public class ClassWithGenericInterceptors
 {
     private int _field = 42;

AutoProperties.Fody/InstructionSequences.cs

@@ -22,7 +22,7 @@ public InstructionSequences([NotNull, ItemNotNull] IList<Instruction> instructio
         [NotNull, ItemNotNull]
         private static IEnumerable<InstructionSequence> CreateSequences([NotNull, ItemNotNull] IList<Instruction> instructions, [CanBeNull, ItemNotNull] IList<SequencePoint> sequencePoints)
         {
-            if (sequencePoints == null)
+            if (sequencePoints?.Any() != true)
             {
                 yield return new InstructionSequence(instructions, null, instructions.Count, null);
                 yield break;

Tests/InterceptorTests.cs

@@ -18,6 +18,8 @@ public class InterceptorTests
     [TestCase("ClassWithExternalInterceptorsBase", 0)]
     [TestCase("ClassWithExternalGenericInterceptorsBase", 0)]
     [TestCase("ClassWithInterceptorsUsingAllPossibleParameters", 3)]
+    [TestCase("ClassWithReadonlyProperty", 1)]
+    [TestCase("ClassDerivedFromClassWithAbstractProperty", 0)]
     public void SimpleInterceptorTest([NotNull] string className, int expectedNumberOfFields)
     {
         var target = assembly.GetInstance(className);