From 8dc84d19b4293a8bd20b47133cac3f544c2e060b Mon Sep 17 00:00:00 2001
From: Amin Jamal <amin.jamal@bayer.com>
Date: Tue, 7 Oct 2025 18:21:28 +0200
Subject: [PATCH] chore: improve naming and enhance comments

---
 src/diff/delta.py  |  2 +-
 src/diff/diff.py   | 45 +++++++++++++++++++++++++--------------------
 src/diff/patch.py  |  3 ++-
 tests/test_diff.py | 19 ++++++++++++++-----
 4 files changed, 42 insertions(+), 27 deletions(-)

diff --git a/src/diff/delta.py b/src/diff/delta.py
index e2402bd..32cf079 100644
--- a/src/diff/delta.py
+++ b/src/diff/delta.py
@@ -4,7 +4,7 @@
 
 @dataclasses.dataclass
 class Delta:
-    op: typing.Literal["deleted", "modified", "added"]
+    operation: typing.Literal["deleted", "modified", "added"]
     path: str
     new_value: typing.Any | None
     old_value: typing.Any | None
diff --git a/src/diff/diff.py b/src/diff/diff.py
index 7fda207..81def81 100644
--- a/src/diff/diff.py
+++ b/src/diff/diff.py
@@ -1,41 +1,46 @@
+import typing
+
 from diff import json_path
 from diff.delta import Delta
 
 
-def diff(new: dict, old: dict) -> list[Delta]:
+def diff(new: dict[str, typing.Any], old: dict[str, typing.Any]) -> list[Delta]:
     new_path_map = json_path.path_value_map(
         new, include_root=True, leaves_only=True, include_containers=False
     )
     old_path_map = json_path.path_value_map(
         old, include_root=True, leaves_only=False, include_containers=False
     )
-    ops: list[Delta] = []
+    operations: list[Delta] = []
 
-    # deleted
     deleted = old_path_map.keys() - new_path_map.keys()
-    for item in deleted:
-        ops.append(  # noqa: PERF401
-            Delta(path=item, op="deleted", old_value=old_path_map[item], new_value=None)
+    for key in deleted:
+        operations.append(  # noqa: PERF401
+            Delta(
+                path=key,
+                operation="deleted",
+                old_value=old_path_map[key],
+                new_value=None,
+            )
         )
 
-    # added
     added = new_path_map.keys() - old_path_map.keys()
-    for item in added:
-        ops.append(  # noqa: PERF401
-            Delta(path=item, op="added", old_value=None, new_value=new_path_map[item])
+    for key in added:
+        operations.append(  # noqa: PERF401
+            Delta(
+                path=key, operation="added", old_value=None, new_value=new_path_map[key]
+            )
         )
 
-    # modified
     shared_keys = new_path_map.keys() & old_path_map.keys()
-    for item in shared_keys:
-        if old_path_map[item] != new_path_map[item]:
-            ops.append(  # noqa: PERF401
+    for key in shared_keys:
+        if old_path_map[key] != new_path_map[key]:
+            operations.append(  # noqa: PERF401
                 Delta(
-                    path=item,
-                    op="modified",
-                    old_value=old_path_map[item],
-                    new_value=new_path_map[item],
+                    path=key,
+                    operation="modified",
+                    old_value=old_path_map[key],
+                    new_value=new_path_map[key],
                 )
             )
-    # exlude root diff
-    return ops
+    return operations
diff --git a/src/diff/patch.py b/src/diff/patch.py
index bc31a00..64e452e 100644
--- a/src/diff/patch.py
+++ b/src/diff/patch.py
@@ -356,9 +356,10 @@ def pop_by_json_path(
 def patch(base: dict[str, typing.Any], deltas: list[Delta]) -> dict[str, typing.Any]:
     output = copy.deepcopy(base)
     for op in deltas:
-        if op.op == "deleted":
+        if op.operation == "deleted":
             pop_by_json_path(output, op.path, prune_empty=True, remove_from_list=True)
             continue
+        # we use set for both modify and add actions
         set_by_json_path(
             output,
             op.path,
diff --git a/tests/test_diff.py b/tests/test_diff.py
index 3020d6a..d3a5512 100644
--- a/tests/test_diff.py
+++ b/tests/test_diff.py
@@ -37,7 +37,14 @@ def _mk_expected_operation(**kwargs):
         (
             {"name": "Amin"},
             {"name": "Amin2"},
-            [Delta(op="modified", path="$.name", old_value="Amin", new_value="Amin2")],
+            [
+                Delta(
+                    operation="modified",
+                    path="$.name",
+                    old_value="Amin",
+                    new_value="Amin2",
+                )
+            ],
         )
     ],
 )
@@ -76,7 +83,9 @@ def test_added_key_expected_op_and_patch_roundtrip():
 
     # At least one 'added' operation to $.age (value semantics may differ: new_value vs value)
     assert any(
-        o.op == "added" and o.path == "$.age" and _op_get(o, "new_value", "value") == 30
+        o.operation == "added"
+        and o.path == "$.age"
+        and _op_get(o, "new_value", "value") == 30
         for o in ops
     )
 
@@ -91,7 +100,7 @@ def test_deleted_key_expected_op_and_patch_roundtrip():
 
     # At least one 'deleted' operation from $.name (old_value/value semantics)
     assert any(
-        o.op == "deleted"
+        o.operation == "deleted"
         and o.path == "$.name"
         and _op_get(o, "old_value", "value") == "Amin"
         for o in ops
@@ -151,7 +160,7 @@ def test_none_handling_as_value_vs_absence():
     old2 = {"y": None}
     new2: dict[str, typing.Any] = {}
     ops2 = diff(new=new2, old=old2)
-    assert any(o.op == "deleted" and o.path == "$.y" for o in ops2)
+    assert any(o.operation == "deleted" and o.path == "$.y" for o in ops2)
     assert patch(base=old2, deltas=ops2) == new2
 
 
@@ -176,7 +185,7 @@ def test_multiple_changes_in_one_structure():
         "$.user.role": "added",
         "$.settings.theme": "modified",
     }
-    seen = {o.path: o.op for o in ops if o.path in expect_paths}
+    seen = {o.path: o.operation for o in ops if o.path in expect_paths}
     for p, expected_op in expect_paths.items():
         assert seen.get(p) == expected_op, (
             f"Expected {expected_op} at {p}, got {seen.get(p)}"