test(gapic-generator): Update gapic generator to resolve pytest-asyncio errors. (#17260)

This PR updates the Python GAPIC generator templates to support modern
EOL Python support drops natively across the entire SDK.

### Changes
* **setup.py.j2**: Bumps the baseline minimum `grpcio` dependency
requirement to `>= 1.59.0`. This robust minimum requirement resolves the
`pytest-asyncio` event loop regressions universally, removing the need
for custom `pytest-asyncio` overrides.
* **noxfile.py.j2**: Replaced the hardcoded constraints path with a
dynamic constraints file path resolver at runtime, ensuring that
monorepos natively resolve to their version-specific constraints files
(e.g., `testing/constraints-3.10.txt`).
* **pytest-asyncio** Updates the gapic-generator in order to resolve an
issue with `pytest-asyncio` failures across Python runtimes 3.10 - 3.14.

Author: chalmerlowe

packages/gapic-generator/gapic/templates/noxfile.py.j2

@@ -41,7 +41,12 @@ PREVIEW_PYTHON_VERSION = "3.14"
 
 CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
 
-LOWER_BOUND_CONSTRAINTS_FILE = CURRENT_DIRECTORY / "constraints.txt"
+if (CURRENT_DIRECTORY / "testing").exists():
+    LOWER_BOUND_CONSTRAINTS_FILE = (
+        CURRENT_DIRECTORY / "testing" / f"constraints-{ALL_PYTHON[0]}.txt"
+    )
+else:
+    LOWER_BOUND_CONSTRAINTS_FILE = CURRENT_DIRECTORY / "constraints.txt"
 PACKAGE_NAME = "{{ api.naming.warehouse_package_name }}"
 
 UNIT_TEST_STANDARD_DEPENDENCIES = [

packages/gapic-generator/gapic/templates/setup.py.j2

@@ -37,7 +37,7 @@ dependencies = [
     # Exclude incompatible versions of `google-auth`
     # See https://github.com/googleapis/google-cloud-python/issues/12364
     "google-auth >= 2.14.1, <3.0.0,!=2.24.0,!=2.25.0",
-    "grpcio >= 1.44.0, < 2.0.0",
+    "grpcio >= 1.59.0, < 2.0.0",
     "grpcio >= 1.75.1, < 2.0.0; python_version >= '3.14'",
     "proto-plus >= 1.22.3, <2.0.0",
     "proto-plus >= 1.25.0, <2.0.0; python_version >= '3.13'",

packages/gapic-generator/gapic/templates/testing/constraints-3.10-async-rest.txt.j2

@@ -10,7 +10,7 @@
 # then this file should have google-cloud-foo==1.14.0
 google-api-core==2.21.0
 google-auth==2.35.0
-grpcio==1.44.0
+grpcio==1.59.0
 proto-plus==1.22.3
 protobuf==4.25.8
 {% for package_tuple, package_info in pypi_packages.items() %}

packages/gapic-generator/gapic/templates/testing/constraints-3.10.txt.j2

@@ -7,7 +7,7 @@
 # then this file should have google-cloud-foo==1.14.0
 google-api-core==2.17.1
 google-auth==2.14.1
-grpcio==1.44.0
+grpcio==1.59.0
 proto-plus==1.22.3
 protobuf==4.25.8
 {% for package_tuple, package_info in pypi_packages.items() %}

packages/gapic-generator/gapic/templates/tests/unit/gapic/%name_%version/%sub/test_%service.py.j2

@@ -7,6 +7,7 @@
 {% import "%namespace/%name_%version/%sub/services/%service/_shared_macros.j2" as shared_macros %}
 
 import os
+import asyncio
 {% if api.all_method_settings.values()|map(attribute="auto_populated_fields", default=[])|select|list %}
 import re
 {% endif %}
@@ -140,6 +141,21 @@ def modify_default_endpoint_template(client):
     return "test.{UNIVERSE_DOMAIN}" if ("localhost" in client._DEFAULT_ENDPOINT_TEMPLATE) else client._DEFAULT_ENDPOINT_TEMPLATE
 
 
+@pytest.fixture(autouse=True)
+def set_event_loop():
+    try:
+        asyncio.get_running_loop()
+        yield
+    except RuntimeError:
+        loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(loop)
+        try:
+            yield
+        finally:
+            loop.close()
+            asyncio.set_event_loop(None)
+
+
 def test__get_default_mtls_endpoint():
     api_endpoint = "example.googleapis.com"
     api_mtls_endpoint = "example.mtls.googleapis.com"

packages/gapic-generator/noxfile.py

@@ -482,6 +482,9 @@ def run_showcase_unit_tests(session, fail_under=100, rest_async_io_enabled=False
         "pytest-xdist",
         "pytest-asyncio",
     )
+    # Freeze and print python environment package versions
+    session.run("python", "-m", "pip", "freeze")
+
     # Run the tests.
     session.run(
         "py.test",

packages/gapic-generator/rules_python_gapic/test/integration_test.bzl

@@ -114,7 +114,7 @@ def _overwrite_golden_impl(ctx):
     golden_update_script_content = """
     cd ${{BUILD_WORKSPACE_DIRECTORY}}
     # Filename pattern-based removal is needed to preserve the BUILD.bazel file.
-    find tests/integration/goldens/{api_name}/ -name \\*.py-type f -delete
+    find tests/integration/goldens/{api_name}/ -name \\*.py -type f -delete
     find tests/integration/goldens/{api_name}/ -name \\*.json -type f -delete
     unzip -ao {goldens_output_zip} -d tests/integration/goldens/{api_name}
     """.format(

packages/gapic-generator/tests/integration/goldens/asset/noxfile.py

@@ -48,7 +48,12 @@
 
 CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
 
-LOWER_BOUND_CONSTRAINTS_FILE = CURRENT_DIRECTORY / "constraints.txt"
+if (CURRENT_DIRECTORY / "testing").exists():
+    LOWER_BOUND_CONSTRAINTS_FILE = (
+        CURRENT_DIRECTORY / "testing" / f"constraints-{ALL_PYTHON[0]}.txt"
+    )
+else:
+    LOWER_BOUND_CONSTRAINTS_FILE = CURRENT_DIRECTORY / "constraints.txt"
 PACKAGE_NAME = "google-cloud-asset"
 
 UNIT_TEST_STANDARD_DEPENDENCIES = [

packages/gapic-generator/tests/integration/goldens/asset/setup.py

@@ -43,7 +43,7 @@
     # Exclude incompatible versions of `google-auth`
     # See https://github.com/googleapis/google-cloud-python/issues/12364
     "google-auth >= 2.14.1, <3.0.0,!=2.24.0,!=2.25.0",
-    "grpcio >= 1.44.0, < 2.0.0",
+    "grpcio >= 1.59.0, < 2.0.0",
     "grpcio >= 1.75.1, < 2.0.0; python_version >= '3.14'",
     "proto-plus >= 1.22.3, <2.0.0",
     "proto-plus >= 1.25.0, <2.0.0; python_version >= '3.13'",

packages/gapic-generator/tests/integration/goldens/asset/testing/constraints-3.10.txt

@@ -6,7 +6,7 @@
 # then this file should have google-cloud-foo==1.14.0
 google-api-core==2.17.1
 google-auth==2.14.1
-grpcio==1.44.0
+grpcio==1.59.0
 proto-plus==1.22.3
 protobuf==4.25.8
 google-cloud-access-context-manager==0.2.0