Address review nits: named FetchNextPage alias and HTTP call count assertions

- Extract the page-fetch callable type into a named `FetchNextPage` alias in
  `typedef.py` so future paginated endpoints have a canonical type to reference
  instead of repeating the inline `Callable[[str], tuple[list[T], str | None]]`
  signature.
- Wrap `catalog._session.get` in both integration tests and assert call count
  equals the number of items — proves `rest-page-size=1` is actually triggering
  one HTTP fetch per item rather than silently returning everything in one shot.

Author: stark256-spec

pyiceberg/typedef.py

@@ -216,6 +216,8 @@ def __hash__(self) -> int:
 TableVersion: TypeAlias = Literal[1, 2, 3]
 ViewVersion: TypeAlias = Literal[1]
 
+FetchNextPage: TypeAlias = Callable[[str], tuple[list[T], str | None]]
+
 
 class PaginationList(list[T]):
     """A list that lazily fetches subsequent pages from a paginated API.
@@ -229,15 +231,15 @@ class PaginationList(list[T]):
         first_page: Items from the first API response.
         next_page_token: Pagination token returned with the first response,
             or ``None`` if no further pages exist.
-        fetch_next_page: Callable that accepts a page token and returns a
-            tuple of ``(items, next_page_token_or_None)``.
+        fetch_next_page: Callable matching ``FetchNextPage[T]`` — accepts a
+            page token and returns ``(items, next_page_token_or_None)``.
     """
 
     def __init__(
         self,
         first_page: list[T],
         next_page_token: str | None,
-        fetch_next_page: Callable[[str], tuple[list[T], str | None]],
+        fetch_next_page: FetchNextPage[T],
     ) -> None:
         super().__init__(first_page)
         self._next_page_token = next_page_token

tests/integration/test_rest_catalog.py

@@ -17,6 +17,7 @@
 # pylint:disable=redefined-outer-name
 
 import time
+from unittest.mock import patch
 
 import pytest
 from pytest_lazy_fixtures import lf
@@ -125,12 +126,14 @@ def test_list_tables_returns_pagination_list(table_schema_nested: Schema, databa
         catalog.create_table((database_name, table_name), table_schema_nested)
 
     try:
-        result = catalog.list_tables(database_name)
-
-        assert isinstance(result, PaginationList)
-        assert len(result) == len(table_list)
-        for table_name in table_list:
-            assert (database_name, table_name) in result
+        with patch.object(catalog._session, "get", wraps=catalog._session.get) as mock_get:
+            result = catalog.list_tables(database_name)
+
+            assert isinstance(result, PaginationList)
+            assert len(result) == len(table_list)
+            for table_name in table_list:
+                assert (database_name, table_name) in result
+            assert mock_get.call_count == len(table_list)
     finally:
         clean_up(catalog)
 
@@ -144,10 +147,12 @@ def test_list_namespaces_returns_pagination_list(database_list: list[str]) -> No
             catalog.create_namespace(namespace)
 
     try:
-        result = catalog.list_namespaces()
+        with patch.object(catalog._session, "get", wraps=catalog._session.get) as mock_get:
+            result = catalog.list_namespaces()
 
-        assert isinstance(result, PaginationList)
-        for namespace in database_list:
-            assert (namespace,) in result
+            assert isinstance(result, PaginationList)
+            for namespace in database_list:
+                assert (namespace,) in result
+            assert mock_get.call_count == len(result)
     finally:
         clean_up(catalog)