助手只想改电话，为什么把营业时间清空了？

"""Local JSON Merge Patch exercise; no HTTP, model, or real merchant changes."""
from copy import deepcopy
import json
from pathlib import Path


def same_json(left, right):
    return json.dumps(left, sort_keys=True, allow_nan=False) == json.dumps(
        right, sort_keys=True, allow_nan=False)


def merge_patch(target, patch):
    # Operates on already parsed JSON values. Object members with null are removed.
    if not isinstance(patch, dict):
        return deepcopy(patch)
    result = deepcopy(target) if isinstance(target, dict) else {}
    for key, value in patch.items():
        if value is None:
            result.pop(key, None)
        else:
            result[key] = merge_patch(result.get(key), value)
    return result


def snapshot(obj, key):
    return {"present": key in obj, "value": deepcopy(obj.get(key))}


def changes(before, after, path=()):
    """Readable leaf changes; path is a list of keys, NOT a JSON Pointer."""
    if isinstance(before, dict) and isinstance(after, dict):
        rows = []
        for key in sorted(before.keys() | after.keys()):
            old, new = snapshot(before, key), snapshot(after, key)
            if old["present"] and new["present"]:
                rows.extend(changes(old["value"], new["value"], path + (key,)))
            elif old != new:
                rows.append({"path": list(path + (key,)), "before": old, "after": new})
        return rows
    if same_json(before, after):
        return []
    return [{"path": list(path), "before": {"present": True, "value": deepcopy(before)},
             "after": {"present": True, "value": deepcopy(after)}}]


def run_case(name, before, patch):
    original, original_patch = deepcopy(before), deepcopy(patch)
    after = merge_patch(before, patch)
    assert before == original and patch == original_patch
    return {"case": name, "before": original, "patch": original_patch,
            "after": after, "changes": changes(before, after)}


def main():
    shop = {"name": "Fictional Tea", "phone": "010-1000", "hours": "09:00-18:00",
            "contact": {"email": "demo@example.invalid", "note": "upstairs"},
            "tags": ["tea", "quiet"], "closed": True}
    cases = [
        run_case("phone_only", shop, {"phone": "010-2000"}),
        run_case("remove_phone", shop, {"phone": None}),
        run_case("empty_phone", shop, {"phone": ""}),
        run_case("nested_note", shop, {"contact": {"note": "ground floor"}}),
        run_case("replace_tags", shop, {"tags": ["tea"]}),
        run_case("false_is_a_value", shop, {"closed": False}),
        run_case("empty_object", shop, {}),
        run_case("dangerous_defaults", shop, {"phone": "010-2000", "hours": None}),
        run_case("root_null", shop, None),
    ]
    by_name = {row["case"]: row for row in cases}
    phone = by_name["phone_only"]
    assert phone["after"]["hours"] == shop["hours"]
    assert [row["path"] for row in phone["changes"]] == [["phone"]]
    assert "phone" not in by_name["remove_phone"]["after"]
    assert by_name["empty_phone"]["after"]["phone"] == ""
    assert by_name["nested_note"]["after"]["contact"]["email"] == shop["contact"]["email"]
    assert by_name["replace_tags"]["after"]["tags"] == ["tea"]
    assert by_name["false_is_a_value"]["after"]["closed"] is False
    assert by_name["empty_object"]["changes"] == []
    assert "hours" not in by_name["dangerous_defaults"]["after"]
    assert by_name["root_null"]["after"] is None
    assert merge_patch({"x": None}, {}) == {"x": None}
    assert merge_patch({}, {"absent": None}) == {}
    assert merge_patch([1, 2], {"a": 1}) == {"a": 1}
    assert merge_patch({"a": 1}, [2, 3]) == [2, 3]
    assert len(changes({"x": True}, {"x": 1})) == 1
    cloned = merge_patch(shop, {})
    cloned["contact"]["note"] = "changed later"
    assert shop["contact"]["note"] == "upstairs"
    report = {"scope": "parsed JSON fixtures; no API adapter or concurrency control",
              "cases": cases, "assertions": "passed"}
    Path("sparse-update-report.json").write_text(
        json.dumps(report, ensure_ascii=False, indent=2) + "\n", encoding="utf-8")
    for row in cases:
        print(f"{row['case']}: changed={len(row['changes'])}")
    print("PASS: missing, null, empty, nested, array, false, root replacement, input isolation")


if __name__ == "__main__":
    main()