Add some utils that have been duplicated in various code bases (#378)

* Add utils to sort records with same syntax as server

* Add utils to compare records

* Add collection_diff util

src/kinto_http/utils.py

@@ -1,6 +1,7 @@
 import functools
 import json
 import re
+import sys
 import unicodedata
 from datetime import date, datetime
 
@@ -9,6 +10,9 @@
 from kinto_http.constants import VALID_SLUG_REGEXP
 
 
+MAX_LENGTH_INT = len(str(sys.maxsize * 2 + 1))
+
+
 def slugify(value):
     """Normalizes string, converts to lowercase, removes non-alpha characters
     and converts spaces to hyphens.
@@ -57,3 +61,52 @@ def json_iso_datetime(obj):
 
 
 json_dumps = functools.partial(json.dumps, default=json_iso_datetime)
+
+
+def sort_records(records, sort):
+    """
+    Sort records following the same format as the server ``name,-last_modified``.
+    """
+
+    def reversed(way, value):
+        if isinstance(value, (int, float)):
+            value = str(way * value).zfill(MAX_LENGTH_INT)
+        if isinstance(value, str):
+            return "".join(chr(255 - ord(c)) for c in value) if way < 0 else value
+        return str(value)
+
+    sort_fields = [
+        (-1, f.strip()[1:]) if f.startswith("-") else (1, f.strip()) for f in sort.split(",")
+    ]
+    return sorted(
+        records, key=lambda r: tuple(reversed(way, r.get(field)) for way, field in sort_fields)
+    )
+
+
+def records_equal(a, b):
+    """
+    Compare records attributes, ignoring those assigned automatically
+    by the server.
+    """
+    ignore_fields = ("last_modified", "schema")
+    ac = {k: v for k, v in a.items() if k not in ignore_fields}
+    bc = {k: v for k, v in b.items() if k not in ignore_fields}
+    return ac == bc
+
+
+def collection_diff(src, dest):
+    """
+    Compare two lists of records.
+    """
+    dest_by_id = {r["id"]: r for r in dest}
+    to_create = []
+    to_update = []
+    for r in src:
+        record = dest_by_id.pop(r["id"], None)
+        if record is None:
+            to_create.append(r)
+        elif not records_equal(r, record):
+            r.pop("last_modified", None)
+            to_update.append((record, r))
+    to_delete = list(dest_by_id.values())
+    return to_create, to_update, to_delete

tests/test_utils.py

@@ -53,3 +53,187 @@ def test_quote_strips_extra_quotes():
 
 def test_quotes_can_take_integers():
     assert utils.quote(1234) == '"1234"'
+
+
+def test_sort_single_field_ascending():
+    records = [
+        {"name": "Charlie", "age": 25},
+        {"name": "Alice", "age": 30},
+        {"name": "Bob", "age": 20},
+    ]
+    result = utils.sort_records(records, "name")
+    expected = [
+        {"name": "Alice", "age": 30},
+        {"name": "Bob", "age": 20},
+        {"name": "Charlie", "age": 25},
+    ]
+    assert result == expected
+
+
+def test_sort_single_field_descending():
+    records = [
+        {"name": "Charlie", "age": 25},
+        {"name": "Alice", "age": 30},
+        {"name": "Bob", "age": 20},
+    ]
+    result = utils.sort_records(records, "-name")
+    expected = [
+        {"name": "Charlie", "age": 25},
+        {"name": "Bob", "age": 20},
+        {"name": "Alice", "age": 30},
+    ]
+    assert result == expected
+
+
+def test_sort_multiple_fields():
+    records = [
+        {"name": "Alice", "age": 30},
+        {"name": "Bob", "age": 25},
+        {"name": "Alice", "age": 20},
+    ]
+    result = utils.sort_records(records, "name,-age")
+    expected = [
+        {"name": "Alice", "age": 30},
+        {"name": "Alice", "age": 20},
+        {"name": "Bob", "age": 25},
+    ]
+    assert result == expected
+
+
+def test_sort_missing_field():
+    records = [
+        {"name": "Charlie", "age": 25},
+        {"name": "Alice"},
+        {"name": "Bob", "age": 20},
+    ]
+    result = utils.sort_records(records, "age")
+    expected = [
+        {"name": "Bob", "age": 20},
+        {"name": "Charlie", "age": 25},
+        {"name": "Alice"},  # Missing "age" is treated as default
+    ]
+    assert result == expected
+
+
+def test_sort_numeric_field_descending():
+    records = [
+        {"name": "Charlie", "score": 85},
+        {"name": "Alice", "score": 95},
+        {"name": "Bob", "score": 111},
+    ]
+    result = utils.sort_records(records, "-score")
+    expected = [
+        {"name": "Bob", "score": 111},
+        {"name": "Alice", "score": 95},
+        {"name": "Charlie", "score": 85},
+    ]
+    assert result == expected
+
+
+def test_sort_mixed_numeric_and_string():
+    records = [
+        {"name": "Charlie", "age": 25},
+        {"name": "Alice", "age": 20},
+        {"name": "Bob", "age": 20},
+    ]
+    result = utils.sort_records(records, "age,-name")
+    expected = [
+        {"name": "Bob", "age": 20},
+        {"name": "Alice", "age": 20},
+        {"name": "Charlie", "age": 25},
+    ]
+    assert result == expected
+
+
+def test_records_equal_identical_records():
+    a = {"id": 1, "name": "Alice", "last_modified": 123, "schema": "v1"}
+    b = {"id": 1, "name": "Alice", "last_modified": 456, "schema": "v2"}
+    assert utils.records_equal(a, b)
+
+
+def test_records_equal_different_records():
+    a = {"id": 1, "name": "Alice", "last_modified": 123}
+    b = {"id": 2, "name": "Bob", "last_modified": 456}
+    assert not utils.records_equal(a, b)
+
+
+def test_records_equal_missing_fields():
+    a = {"id": 1, "name": "Alice", "last_modified": 123}
+    b = {"id": 1, "name": "Alice"}
+    assert utils.records_equal(a, b)
+
+
+def test_records_equal_extra_fields():
+    a = {"id": 1, "name": "Alice", "extra": "field"}
+    b = {"id": 1, "name": "Alice"}
+    assert not utils.records_equal(a, b)
+
+
+def test_records_equal_empty_records():
+    a = {}
+    b = {}
+    assert utils.records_equal(a, b)
+
+
+def test_records_equal_only_ignored_fields():
+    a = {"last_modified": 123, "schema": "v1"}
+    b = {"last_modified": 456, "schema": "v2"}
+    assert utils.records_equal(a, b)
+
+
+def test_collection_diff_create():
+    src = [{"id": 1, "name": "Alice"}]
+    dest = []
+    to_create, to_update, to_delete = utils.collection_diff(src, dest)
+    assert to_create == [{"id": 1, "name": "Alice"}]
+    assert to_update == []
+    assert to_delete == []
+
+
+def test_collection_diff_update():
+    src = [{"id": 1, "name": "Alice"}]
+    dest = [{"id": 1, "name": "Bob"}]
+    to_create, to_update, to_delete = utils.collection_diff(src, dest)
+    assert to_create == []
+    assert to_update == [({"id": 1, "name": "Bob"}, {"id": 1, "name": "Alice"})]
+    assert to_delete == []
+
+
+def test_collection_diff_delete():
+    src = []
+    dest = [{"id": 1, "name": "Alice"}]
+    to_create, to_update, to_delete = utils.collection_diff(src, dest)
+    assert to_create == []
+    assert to_update == []
+    assert to_delete == [{"id": 1, "name": "Alice"}]
+
+
+def test_collection_diff_mixed():
+    src = [{"id": 1, "name": "Alice"}, {"id": 2, "name": "Bob"}, {"id": 3, "name": "Charlie"}]
+    dest = [
+        {"id": 2, "name": "Bob"},
+        {"id": 3, "name": "CharlieUpdated"},
+        {"id": 4, "name": "Dave"},
+    ]
+    to_create, to_update, to_delete = utils.collection_diff(src, dest)
+    assert to_create == [{"id": 1, "name": "Alice"}]
+    assert to_update == [({"id": 3, "name": "CharlieUpdated"}, {"id": 3, "name": "Charlie"})]
+    assert to_delete == [{"id": 4, "name": "Dave"}]
+
+
+def test_collection_diff_no_changes():
+    src = [{"id": 1, "name": "Alice"}]
+    dest = [{"id": 1, "name": "Alice"}]
+    to_create, to_update, to_delete = utils.collection_diff(src, dest)
+    assert to_create == []
+    assert to_update == []
+    assert to_delete == []
+
+
+def test_collection_diff_empty_collections():
+    src = []
+    dest = []
+    to_create, to_update, to_delete = utils.collection_diff(src, dest)
+    assert to_create == []
+    assert to_update == []
+    assert to_delete == []