pythonnet · rickardraysearch · Aug 9, 2017 · Aug 9, 2017 · Aug 9, 2017 · Aug 9, 2017
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -16,6 +16,7 @@ This document follows the conventions laid out in [Keep a CHANGELOG][].
 -   Added `clr.GetClrType` (#432, #433)
 -   Allowed passing `None` for nullable args (#460)
 -   Added keyword arguments based on C# syntax for calling CPython methods (#461)
+-   Catches exceptions thrown in C# iterators (yield returns) and rethrows them in python (#475)
 -   Implemented GetDynamicMemberNames() for PyObject to allow dynamic object members to be visible in the debugger (#443)

 ### Changed

diff --git a/src/runtime/iterator.cs b/src/runtime/iterator.cs
@@ -23,9 +23,21 @@ public Iterator(IEnumerator e)
        public static IntPtr tp_iternext(IntPtr ob)
        {
            var self = GetManagedObject(ob) as Iterator;
-            if (!self.iter.MoveNext())
+            try
            {
-                Exceptions.SetError(Exceptions.StopIteration, Runtime.PyNone);
+                if (!self.iter.MoveNext())
+                {
+                    Exceptions.SetError(Exceptions.StopIteration, Runtime.PyNone);
+                    return IntPtr.Zero;
+                }
+            }
+            catch (Exception e)
+            {
+                if (e.InnerException != null)
+                {
+                    e = e.InnerException;
+                }
+                Exceptions.SetError(e);
                return IntPtr.Zero;
            }
            object item = self.iter.Current;

diff --git a/src/testing/exceptiontest.cs b/src/testing/exceptiontest.cs
@@ -1,4 +1,6 @@
 using System;
+using System.Collections;
+using System.Collections.Generic;

 namespace Python.Test
 {
@@ -54,6 +56,13 @@ public static bool ThrowException()
            throw new OverflowException("error");
        }

+        public static IEnumerable<int> ThrowExceptionInIterator(Exception e)
+        {
+            yield return 1;
+            yield return 2;
+            throw e;
+        }
+
        public static void ThrowChainedExceptions()
        {
            try

diff --git a/src/tests/test_exceptions.py b/src/tests/test_exceptions.py
@@ -345,3 +345,35 @@ def test_chained_exceptions():
        assert exc.Message == msg
        assert exc.__cause__ == exc.InnerException
        exc = exc.__cause__
+
+def test_iteration_exception():
+    from Python.Test import ExceptionTest
+    from System import OverflowException
+
+    exception = OverflowException("error")
+
+    val = ExceptionTest.ThrowExceptionInIterator(exception).__iter__()
+    assert next(val) == 1
+    assert next(val) == 2
+    with pytest.raises(OverflowException) as cm:
+        next(val)
+
+    exc = cm.value
+
+    assert exc == exception
+
+def test_iteration_innerexception():
+    from Python.Test import ExceptionTest
+    from System import OverflowException
+
+    exception = System.Exception("message", OverflowException("error"))
+
+    val = ExceptionTest.ThrowExceptionInIterator(exception).__iter__()
+    assert next(val) == 1
+    assert next(val) == 2
+    with pytest.raises(OverflowException) as cm:
+        next(val)
+
+    exc = cm.value
+
+    assert exc == exception.InnerException