tests: update default runtime used for tests

noxfile.py

@@ -33,8 +33,33 @@
     "docs/conf.py",
 ]
 
+DEFAULT_PYTHON_VERSION = "3.10"
+# TODO(https://github.com/googleapis/google-auth-library-python/issues/1787):
+# Remove or restore testing for Python 3.7/3.8
+UNIT_TEST_PYTHON_VERSIONS = ["3.9", "3.10", "3.11", "3.12", "3.13"]
+
+# Error if a python version is missing
+nox.options.error_on_missing_interpreters = True
+
+# pypy will be run as a github action instead of through Kokoro
+nox.options.sessions = [
+    "lint",
+    "blacken",
+    "mypy",
+    # TODO(https://github.com/googleapis/google-auth-library-python/issues/1787):
+    # Remove or restore testing for Python 3.7/3.8
+    "unit-3.9",
+    "unit-3.10",
+    "unit-3.11",
+    "unit-3.12",
+    "unit-3.13",
+    # cover must be last to avoid error `No data to report`
+    "cover",
+    "docs",
+]
+
 
-@nox.session(python="3.8")
+@nox.session(python=DEFAULT_PYTHON_VERSION)
 def lint(session):
     session.install(
         "flake8", "flake8-import-order", "docutils", CLICK_VERSION, BLACK_VERSION
@@ -54,7 +79,7 @@ def lint(session):
     )
 
 
-@nox.session(python="3.8")
+@nox.session(python=DEFAULT_PYTHON_VERSION)
 def blacken(session):
     """Run black.
     Format code to uniform standard.
@@ -67,7 +92,7 @@ def blacken(session):
     session.run("black", *BLACK_PATHS)
 
 
-@nox.session(python="3.8")
+@nox.session(python=DEFAULT_PYTHON_VERSION)
 def mypy(session):
     """Verify type hints are mypy compatible."""
     session.install("-e", ".")
@@ -84,7 +109,7 @@ def mypy(session):
     session.run("mypy", "-p", "google", "-p", "tests", "-p", "tests_async")
 
 
-@nox.session(python=["3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.13"])
+@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
 def unit(session):
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
@@ -102,7 +127,7 @@ def unit(session):
     )
 
 
-@nox.session(python="3.8")
+@nox.session(python=DEFAULT_PYTHON_VERSION)
 def cover(session):
     session.install("-e", ".[testing]")
     session.run(

system_tests/noxfile.py

@@ -163,8 +163,8 @@ def configure_cloud_sdk(session, application_default_credentials, project=False)
 
 TEST_DEPENDENCIES_ASYNC = ["aiohttp", "pytest-asyncio", "nest-asyncio", "mock"]
 TEST_DEPENDENCIES_SYNC = ["pytest", "requests", "mock", "pyjwt"]
-PYTHON_VERSIONS_ASYNC = ["3.7"]
-PYTHON_VERSIONS_SYNC = ["3.7"]
+PYTHON_VERSIONS_ASYNC = ["3.10"]
+PYTHON_VERSIONS_SYNC = ["3.10"]
 
 
 def default(session, *test_paths):