feat: support overriding the amber serializer class

src/syrupy/extensions/amber/__init__.py

@@ -5,12 +5,14 @@
     Any,
     Optional,
     Set,
+    Type,
 )
 
 from syrupy.data import SnapshotCollection
 from syrupy.exceptions import TaintedSnapshotError
 from syrupy.extensions.base import AbstractSyrupyExtension
 
+from .serializer import AmberDataSerializerSorted  # noqa: F401 # re-exported
 from .serializer import AmberDataSerializer
 
 if TYPE_CHECKING:
@@ -24,12 +26,14 @@ class AmberSnapshotExtension(AbstractSyrupyExtension):
 
     _file_extension = "ambr"
 
+    serializer_class: Type["AmberDataSerializer"] = AmberDataSerializer
+
     def serialize(self, data: "SerializableData", **kwargs: Any) -> str:
         """
         Returns the serialized form of 'data' to be compared
         with the snapshot data written to disk.
         """
-        return AmberDataSerializer.serialize(data, **kwargs)
+        return self.serializer_class.serialize(data, **kwargs)
 
     def delete_snapshots(
         self, snapshot_location: str, snapshot_names: Set[str]
@@ -39,19 +43,19 @@ def delete_snapshots(
             snapshot_collection_to_update.remove(snapshot_name)
 
         if snapshot_collection_to_update.has_snapshots:
-            AmberDataSerializer.write_file(snapshot_collection_to_update)
+            self.serializer_class.write_file(snapshot_collection_to_update)
         else:
             Path(snapshot_location).unlink()
 
     def _read_snapshot_collection(self, snapshot_location: str) -> "SnapshotCollection":
-        return AmberDataSerializer.read_file(snapshot_location)
+        return self.serializer_class.read_file(snapshot_location)
 
-    @staticmethod
+    @classmethod
     @lru_cache()
     def __cacheable_read_snapshot(
-        snapshot_location: str, cache_key: str
+        cls, snapshot_location: str, cache_key: str
     ) -> "SnapshotCollection":
-        return AmberDataSerializer.read_file(snapshot_location)
+        return cls.serializer_class.read_file(snapshot_location)
 
     def _read_snapshot_data_from_location(
         self, snapshot_location: str, snapshot_name: str, session_id: str
@@ -70,7 +74,7 @@ def _read_snapshot_data_from_location(
     def _write_snapshot_collection(
         cls, *, snapshot_collection: "SnapshotCollection"
     ) -> None:
-        AmberDataSerializer.write_file(snapshot_collection, merge=True)
+        cls.serializer_class.write_file(snapshot_collection, merge=True)
 
 
 __all__ = ["AmberSnapshotExtension", "AmberDataSerializer"]

src/syrupy/extensions/amber/serializer.py

@@ -11,7 +11,6 @@
     Dict,
     Generator,
     Iterable,
-    List,
     NamedTuple,
     Optional,
     Set,
@@ -77,7 +76,13 @@ class MissingVersionError(Exception):
 
 
 class AmberDataSerializer:
-    VERSION = 1
+    """
+    If extending the serializer, change the VERSION property to some unique value
+    for your iteration of the serializer so as to force invalidation of existing
+    snapshots.
+    """
+
+    VERSION = "1"
 
     _indent: str = "  "
     _max_depth: int = 99
@@ -89,23 +94,8 @@ class Marker:
         Divider = "---"
 
     @classmethod
-    def __maybe_int(cls, part: str) -> Tuple[int, Union[str, int]]:
-        try:
-            # cast to int only if the string is the exact representation of the int
-            # for example, '012' != str(int('012'))
-            i = int(part)
-            if str(i) == part:
-                return (1, i)
-            return (0, part)
-        except ValueError:
-            # the nested tuple is to prevent comparing a str to an int
-            return (0, part)
-
-    @classmethod
-    def __snapshot_sort_key(
-        cls, snapshot: "Snapshot"
-    ) -> List[Tuple[int, Union[str, int]]]:
-        return [cls.__maybe_int(part) for part in snapshot.name.split(".")]
+    def _snapshot_sort_key(cls, snapshot: "Snapshot") -> Any:
+        return snapshot.name
 
     @classmethod
     def write_file(
@@ -123,7 +113,7 @@ def write_file(
         with open(filepath, "w", encoding=TEXT_ENCODING, newline=None) as f:
             f.write(f"{cls._marker_prefix}{cls.Marker.Version}: {cls.VERSION}\n")
             for snapshot in sorted(
-                snapshot_collection, key=lambda s: cls.__snapshot_sort_key(s)
+                snapshot_collection, key=lambda s: cls._snapshot_sort_key(s)  # type: ignore # noqa: E501
             ):
                 snapshot_data = str(snapshot.data)
                 if snapshot_data is not None:
@@ -152,14 +142,14 @@ def __read_file_with_markers(
                             ":", maxsplit=1
                         )
                         marker_key = marker_key.rstrip(" \r\n")
-                        marker_value = marker_rest[0] if marker_rest else None
+                        marker_value = marker_rest[0].strip() if marker_rest else None
 
                         if marker_key == cls.Marker.Version:
                             if line_no:
                                 raise MalformedAmberFile(
                                     "Version must be specified at the top of the file."
                                 )
-                            if not marker_value or int(marker_value) != cls.VERSION:
+                            if not marker_value or marker_value != cls.VERSION:
                                 tainted = True
                                 continue
                             missing_version = False
@@ -457,3 +447,28 @@ def __serialize_lines(
         formatted_open_tag = cls.with_indent(f"{maybe_obj_type}{open_tag}", depth)
         formatted_close_tag = cls.with_indent(close_tag, depth)
         return f"{formatted_open_tag}\n{lines}{lines_end}{formatted_close_tag}"
+
+
+class AmberDataSerializerSorted(AmberDataSerializer):
+    """
+    This is an experimental serializer with known performance issues.
+    """
+
+    VERSION = f"{AmberDataSerializer.VERSION}-sorted"
+
+    @classmethod
+    def __maybe_int(cls, part: str) -> Tuple[int, Union[str, int]]:
+        try:
+            # cast to int only if the string is the exact representation of the int
+            # for example, '012' != str(int('012'))
+            i = int(part)
+            if str(i) == part:
+                return (1, i)
+            return (0, part)
+        except ValueError:
+            # the nested tuple is to prevent comparing a str to an int
+            return (0, part)
+
+    @classmethod
+    def _snapshot_sort_key(cls, snapshot: "Snapshot") -> Any:
+        return [cls.__maybe_int(part) for part in snapshot.name.split(".")]

tests/syrupy/__snapshots__/test_doctest.ambr

@@ -4,6 +4,11 @@
     obj_attr='test class attr',
   )
 # ---
+# name: DocTestClass.1
+  DocTestClass(
+    obj_attr='test class attr',
+  )
+# ---
 # name: DocTestClass.NestedDocTestClass
   NestedDocTestClass(
     nested_obj_attr='nested doc test class attr',
@@ -15,11 +20,6 @@
 # name: DocTestClass.doctest_method
   'doc test method return value'
 # ---
-# name: DocTestClass.1
-  DocTestClass(
-    obj_attr='test class attr',
-  )
-# ---
 # name: doctest_fn
   'doc test fn return value'
 # ---

tests/syrupy/extensions/amber/__snapshots__/test_amber_serializer.ambr

@@ -253,30 +253,6 @@
 # name: test_many_sorted.1
   1
 # ---
-# name: test_many_sorted.2
-  2
-# ---
-# name: test_many_sorted.3
-  3
-# ---
-# name: test_many_sorted.4
-  4
-# ---
-# name: test_many_sorted.5
-  5
-# ---
-# name: test_many_sorted.6
-  6
-# ---
-# name: test_many_sorted.7
-  7
-# ---
-# name: test_many_sorted.8
-  8
-# ---
-# name: test_many_sorted.9
-  9
-# ---
 # name: test_many_sorted.10
   10
 # ---
@@ -307,6 +283,9 @@
 # name: test_many_sorted.19
   19
 # ---
+# name: test_many_sorted.2
+  2
+# ---
 # name: test_many_sorted.20
   20
 # ---
@@ -322,6 +301,27 @@
 # name: test_many_sorted.24
   24
 # ---
+# name: test_many_sorted.3
+  3
+# ---
+# name: test_many_sorted.4
+  4
+# ---
+# name: test_many_sorted.5
+  5
+# ---
+# name: test_many_sorted.6
+  6
+# ---
+# name: test_many_sorted.7
+  7
+# ---
+# name: test_many_sorted.8
+  8
+# ---
+# name: test_many_sorted.9
+  9
+# ---
 # name: test_multiline_string_in_dict
   dict({
     'value': '''

tests/syrupy/extensions/amber_sorted/__snapshots__/test_amber_sort.ambr

@@ -0,0 +1,76 @@
+# serializer version: 1-sorted
+# name: test_many_sorted
+  0
+# ---
+# name: test_many_sorted.1
+  1
+# ---
+# name: test_many_sorted.2
+  2
+# ---
+# name: test_many_sorted.3
+  3
+# ---
+# name: test_many_sorted.4
+  4
+# ---
+# name: test_many_sorted.5
+  5
+# ---
+# name: test_many_sorted.6
+  6
+# ---
+# name: test_many_sorted.7
+  7
+# ---
+# name: test_many_sorted.8
+  8
+# ---
+# name: test_many_sorted.9
+  9
+# ---
+# name: test_many_sorted.10
+  10
+# ---
+# name: test_many_sorted.11
+  11
+# ---
+# name: test_many_sorted.12
+  12
+# ---
+# name: test_many_sorted.13
+  13
+# ---
+# name: test_many_sorted.14
+  14
+# ---
+# name: test_many_sorted.15
+  15
+# ---
+# name: test_many_sorted.16
+  16
+# ---
+# name: test_many_sorted.17
+  17
+# ---
+# name: test_many_sorted.18
+  18
+# ---
+# name: test_many_sorted.19
+  19
+# ---
+# name: test_many_sorted.20
+  20
+# ---
+# name: test_many_sorted.21
+  21
+# ---
+# name: test_many_sorted.22
+  22
+# ---
+# name: test_many_sorted.23
+  23
+# ---
+# name: test_many_sorted.24
+  24
+# ---

tests/syrupy/extensions/amber_sorted/test_amber_sort.py

@@ -0,0 +1,20 @@
+import pytest
+
+from syrupy.extensions.amber import (
+    AmberDataSerializerSorted,
+    AmberSnapshotExtension,
+)
+
+
+class AmberSortedSnapshotExtension(AmberSnapshotExtension):
+    serializer_class = AmberDataSerializerSorted
+
+
+@pytest.fixture
+def snapshot(snapshot):
+    return snapshot.use_extension(AmberSortedSnapshotExtension)
+
+
+def test_many_sorted(snapshot):
+    for i in range(25):
+        assert i == snapshot