ci: use prelease versions only for 3.15

.github/workflows/unittest.yml

@@ -22,7 +22,8 @@ env:
   NOX_ENVDIR: "/tmp/shared_nox_envs"
   NOX_DEFAULT_VENV_BACKEND: "uv"
   UV_VENV_SEED: "1"
-  UV_PRERELEASE: "allow"
+  # Prefer stable versions, falling back to pre-releases only when no stable version exists
+  UV_PRERELEASE: "if-necessary"
   # Note: PARALLEL_WORKERS must remain "1" for unit tests because running pytest concurrently
   # on the same runner VM can cause socket/IPC/process deadlocks across packages.
   PARALLEL_WORKERS: "1"
@@ -124,7 +125,7 @@ jobs:
       with:
         python-version: ${{ matrix.python }}
         cache: 'pip'
-        allow-prereleases: true
+        allow-prereleases: ${{ matrix.python == '3.15' }}
     - name: Setup uv
       uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86 # v5
       with:
@@ -198,7 +199,7 @@ jobs:
       with:
         python-version: ${{ matrix.python }}
         cache: 'pip'
-        allow-prereleases: true
+        allow-prereleases: false
     - name: Install nox
       run: |
         pip install nox

packages/sqlalchemy-spanner/tests/mockserver_tests/test_tags.py

@@ -35,7 +35,7 @@ class TestStaleReads(MockServerTestBase):
     def test_request_tag(self):
         from tests.mockserver_tests.tags_model import Singer
 
-        add_singer_query_result("SELECT singers.id, singers.name \n" + "FROM singers")
+        add_singer_query_result()
         engine = self.create_engine()
 
         with Session(engine.execution_options(read_only=True)) as session:
@@ -61,10 +61,8 @@ def test_request_tag(self):
     def test_transaction_tag(self):
         from tests.mockserver_tests.tags_model import Singer
 
-        add_singer_query_result("SELECT singers.id, singers.name\n" + "FROM singers")
-        add_single_singer_query_result(
-            "SELECT singers.id, singers.name\nFROM singers\nWHERE singers.id = @a0"
-        )
+        add_singer_query_result()
+        add_single_singer_query_result()
         add_update_count("INSERT INTO singers (id, name) VALUES (@a0, @a1)", 1)
         engine = self.create_engine()
 
@@ -129,7 +127,18 @@ def empty_singer_result_set():
     )
 
 
-def add_singer_query_result(sql: str):
+def has_column_aliases() -> bool:
+    # Older SQLAlchemy 2.0.x versions compiled ORM column selections with explicit
+    # labels (e.g., 'singers.id AS singers_id'), whereas newer 2.0.x and 2.1+ releases
+    # omit redundant column aliases in unaliased single-table queries.
+    from tests.mockserver_tests.tags_model import Singer
+
+    return "AS singers_id" in str(select(Singer))
+
+
+def add_singer_query_result():
+    sql = "SELECT singers.id, singers.name\nFROM singers"
+
     result = empty_singer_result_set()
     result.rows.extend(
         [
@@ -146,7 +155,15 @@ def add_singer_query_result(sql: str):
     add_result(sql, result)
 
 
-def add_single_singer_query_result(sql: str):
+def add_single_singer_query_result():
+    if has_column_aliases():
+        sql = (
+            "SELECT singers.id AS singers_id, singers.name AS singers_name"
+            + "\nFROM singers\nWHERE singers.id = @a0"
+        )
+    else:
+        sql = "SELECT singers.id, singers.name\nFROM singers\nWHERE singers.id = @a0"
+
     result = empty_singer_result_set()
     result.rows.extend(
         [