Techdebt: MyPy DynamoDBStreams (#5795)

moto/dynamodbstreams/models.py

@@ -1,14 +1,20 @@
 import os
 import json
 import base64
+from typing import Any, Dict, Optional
 
 from moto.core import BaseBackend, BackendDict, BaseModel
-from moto.dynamodb.models import dynamodb_backends, DynamoJsonEncoder
+from moto.dynamodb.models import dynamodb_backends, DynamoJsonEncoder, DynamoDBBackend
+from moto.dynamodb.models import Table, StreamShard
 
 
 class ShardIterator(BaseModel):
     def __init__(
-        self, streams_backend, stream_shard, shard_iterator_type, sequence_number=None
+        self,
+        streams_backend: "DynamoDBStreamsBackend",
+        stream_shard: StreamShard,
+        shard_iterator_type: str,
+        sequence_number: Optional[int] = None,
     ):
         self.id = base64.b64encode(os.urandom(472)).decode("utf-8")
         self.streams_backend = streams_backend
@@ -21,19 +27,19 @@ class ShardIterator(BaseModel):
                 stream_shard.items
             )
         elif shard_iterator_type == "AT_SEQUENCE_NUMBER":
-            self.sequence_number = sequence_number
+            self.sequence_number = sequence_number  # type: ignore[assignment]
         elif shard_iterator_type == "AFTER_SEQUENCE_NUMBER":
-            self.sequence_number = sequence_number + 1
+            self.sequence_number = sequence_number + 1  # type: ignore[operator]
 
     @property
-    def arn(self):
+    def arn(self) -> str:
         return f"{self.stream_shard.table.table_arn}/stream/{self.stream_shard.table.latest_stream_label}|1|{self.id}"
 
-    def to_json(self):
+    def to_json(self) -> Dict[str, str]:
         return {"ShardIterator": self.arn}
 
-    def get(self, limit=1000):
+    def get(self, limit: int = 1000) -> Dict[str, Any]:
-        items = self.stream_shard.get(self.sequence_number, limit)
+        items = self.stream_shard.get(self.sequence_number, limit)  # type: ignore[no-untyped-call]
         try:
             last_sequence_number = max(
                 int(i["dynamodb"]["SequenceNumber"]) for i in items
@@ -59,19 +65,19 @@ class ShardIterator(BaseModel):
 
 
 class DynamoDBStreamsBackend(BaseBackend):
-    def __init__(self, region_name, account_id):
+    def __init__(self, region_name: str, account_id: str):
         super().__init__(region_name, account_id)
-        self.shard_iterators = {}
+        self.shard_iterators: Dict[str, ShardIterator] = {}
 
     @property
-    def dynamodb(self):
+    def dynamodb(self) -> DynamoDBBackend:
         return dynamodb_backends[self.account_id][self.region_name]
 
-    def _get_table_from_arn(self, arn):
+    def _get_table_from_arn(self, arn: str) -> Table:
         table_name = arn.split(":", 6)[5].split("/")[1]
-        return self.dynamodb.get_table(table_name)
+        return self.dynamodb.get_table(table_name)  # type: ignore[no-untyped-call]
 
-    def describe_stream(self, arn):
+    def describe_stream(self, arn: str) -> str:
         table = self._get_table_from_arn(arn)
         resp = {
             "StreamDescription": {
@@ -81,7 +87,7 @@ class DynamoDBStreamsBackend(BaseBackend):
                     "ENABLED" if table.latest_stream_label else "DISABLED"
                 ),
                 "StreamViewType": table.stream_specification["StreamViewType"],
-                "CreationRequestDateTime": table.stream_shard.created_on.isoformat(),
+                "CreationRequestDateTime": table.stream_shard.created_on.isoformat(),  # type: ignore[union-attr]
                 "TableName": table.name,
                 "KeySchema": table.schema,
                 "Shards": (
@@ -92,7 +98,7 @@ class DynamoDBStreamsBackend(BaseBackend):
 
         return json.dumps(resp)
 
-    def list_streams(self, table_name=None):
+    def list_streams(self, table_name: Optional[str] = None) -> str:
         streams = []
         for table in self.dynamodb.tables.values():
             if table_name is not None and table.name != table_name:
@@ -110,19 +116,23 @@ class DynamoDBStreamsBackend(BaseBackend):
         return json.dumps({"Streams": streams})
 
     def get_shard_iterator(
-        self, arn, shard_id, shard_iterator_type, sequence_number=None
+        self,
-    ):
+        arn: str,
+        shard_id: str,
+        shard_iterator_type: str,
+        sequence_number: Optional[str] = None,
+    ) -> str:
         table = self._get_table_from_arn(arn)
-        assert table.stream_shard.id == shard_id
+        assert table.stream_shard.id == shard_id  # type: ignore[union-attr]
 
         shard_iterator = ShardIterator(
-            self, table.stream_shard, shard_iterator_type, sequence_number
+            self, table.stream_shard, shard_iterator_type, sequence_number  # type: ignore[arg-type]
         )
         self.shard_iterators[shard_iterator.arn] = shard_iterator
 
         return json.dumps(shard_iterator.to_json())
 
-    def get_records(self, iterator_arn, limit):
+    def get_records(self, iterator_arn: str, limit: int) -> str:
         shard_iterator = self.shard_iterators[iterator_arn]
         return json.dumps(shard_iterator.get(limit), cls=DynamoJsonEncoder)
 

moto/dynamodbstreams/responses.py

@@ -1,25 +1,25 @@
 from moto.core.responses import BaseResponse
 
-from .models import dynamodbstreams_backends
+from .models import dynamodbstreams_backends, DynamoDBStreamsBackend
 
 
 class DynamoDBStreamsHandler(BaseResponse):
-    def __init__(self):
+    def __init__(self) -> None:
         super().__init__(service_name="dynamodb-streams")
 
     @property
-    def backend(self):
+    def backend(self) -> DynamoDBStreamsBackend:
         return dynamodbstreams_backends[self.current_account][self.region]
 
-    def describe_stream(self):
+    def describe_stream(self) -> str:
         arn = self._get_param("StreamArn")
         return self.backend.describe_stream(arn)
 
-    def list_streams(self):
+    def list_streams(self) -> str:
         table_name = self._get_param("TableName")
         return self.backend.list_streams(table_name)
 
-    def get_shard_iterator(self):
+    def get_shard_iterator(self) -> str:
         arn = self._get_param("StreamArn")
         shard_id = self._get_param("ShardId")
         shard_iterator_type = self._get_param("ShardIteratorType")
@@ -32,7 +32,7 @@ class DynamoDBStreamsHandler(BaseResponse):
             arn, shard_id, shard_iterator_type, sequence_number
         )
 
-    def get_records(self):
+    def get_records(self) -> str:
         arn = self._get_param("ShardIterator")
         limit = self._get_param("Limit")
         if limit is None:

setup.cfg

@@ -18,7 +18,7 @@ disable = W,C,R,E
 enable = anomalous-backslash-in-string, arguments-renamed, dangerous-default-value, deprecated-module, function-redefined, import-self, redefined-builtin, redefined-outer-name, reimported, pointless-statement, super-with-arguments, unused-argument, unused-import, unused-variable, useless-else-on-loop, wildcard-import
 
 [mypy]
-files= moto/a*,moto/b*,moto/c*,moto/databrew,moto/datapipeline,moto/datasync,moto/dax,moto/dms,moto/moto_api
+files= moto/a*,moto/b*,moto/c*,moto/databrew,moto/datapipeline,moto/datasync,moto/dax,moto/dms,moto/ds,moto/dynamodbstreams,moto/moto_api
 show_column_numbers=True
 show_error_codes = True
 disable_error_code=abstract