Fix appending operation for list

Author: berendkleinhaneveld

patchdiff/apply.py

@@ -19,7 +19,11 @@ def iapply(obj: Diffable, patches: List[Dict]) -> Diffable:
             else:  # add/replace
                 parent[key] = value
         elif hasattr(parent, "append"):  # list
-            key = int(key)
+            try:
+                key = int(key)
+            except ValueError:
+                pass
+
             if op == "replace":
                 parent[key] = value
             elif op == "add":

tests/test_apply.py

@@ -27,3 +27,16 @@ def test_apply():
 
     d = apply(b, rops)
     assert a == d
+
+
+def test_add_remove_list():
+    a = []
+    b = [1]
+
+    ops, rops = diff(a, b)
+
+    c = apply(a, ops)
+    assert c == b
+
+    d = apply(b, rops)
+    assert a == d