tests: refactor unit test nox sessions (#873)

This change is needed as part of b/463296248. Instead of having 4
different presubmits that run 4 different nox unit tests, we now have
all 4 patterns tested under a single nox session. This follows the
pattern that we have in google-cloud-python where there is a single unit
test nox session.

Author: parthea

.github/workflows/unittest.yml

@@ -6,15 +6,38 @@ on:
       - main
 
 jobs:
-  run-unittests:
+  unit-prerelease:
+    name: prerelease_deps
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python: ["3.14"]
+        option: ["prerelease"]
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+    - name: Setup Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: ${{ matrix.python }}
+        allow-prereleases: true
+    - name: Install nox
+      run: |
+        python -m pip install --upgrade setuptools pip wheel
+        python -m pip install nox
+    - name: Run ${{ matrix.option }} tests
+      env:
+        COVERAGE_FILE: .coverage${{ matrix.option }}-${{matrix.python }}
+      run: |
+        nox -s prerelease_deps
+  unit:
     name: unit${{ matrix.option }}-${{ matrix.python }}
     # TODO(https://github.com/googleapis/gapic-generator-python/issues/2303): use `ubuntu-latest` once this bug is fixed.
     # Use ubuntu-22.04 until Python 3.7 is removed from the test matrix
     # https://docs.github.com/en/actions/using-github-hosted-runners/using-github-hosted-runners/about-github-hosted-runners#standard-github-hosted-runners-for-public-repositories
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        option: ["", "_grpc_gcp", "_wo_grpc", "_w_prerelease_deps", "_w_async_rest_extra"]
         python:
           - "3.7"
           - "3.8"
@@ -24,13 +47,6 @@ jobs:
           - "3.12"
           - "3.13"
           - "3.14"
-        exclude:
-          - option: "_wo_grpc"
-            python: 3.7
-          - option: "_wo_grpc"
-            python: 3.8
-          - option: "_wo_grpc"
-            python: 3.9
     steps:
     - name: Checkout
       uses: actions/checkout@v4
@@ -45,21 +61,21 @@ jobs:
         python -m pip install nox
     - name: Run unit tests
       env:
-        COVERAGE_FILE: .coverage${{ matrix.option }}-${{matrix.python }}
+        COVERAGE_FILE: .coverage-${{matrix.python }}
       run: |
-        nox -s unit${{ matrix.option }}-${{ matrix.python }}
+        nox -s unit-${{ matrix.python }}
     - name: Upload coverage results
       uses: actions/upload-artifact@v4
       with:
-        name: coverage-artifact-${{ matrix.option }}-${{ matrix.python }}
-        path: .coverage${{ matrix.option }}-${{ matrix.python }}
+        name: coverage-artifact-${{ matrix.python }}
+        path: .coverage-${{ matrix.python }}
         include-hidden-files: true
 
   report-coverage:
     name: cover
     runs-on: ubuntu-latest
     needs:
-        - run-unittests
+        - unit
     steps:
     - name: Checkout
       uses: actions/checkout@v4

noxfile.py

@@ -215,46 +215,41 @@ def default(session, install_grpc=True, prerelease=False, install_async_rest=Fal
 
 
 @nox.session(python=PYTHON_VERSIONS)
-def unit(session):
+@nox.parametrize(
+    ["install_grpc_gcp", "install_grpc", "install_async_rest"],
+    [
+        (False, True, False),  # Run unit tests with grpcio installed
+        (True, True, False),  # Run unit tests with grpcio/grpcio-gcp installed
+        (False, False, False),  # Run unit tests without grpcio installed
+        (False, True, True),  # Run unit tests with grpcio and async rest installed
+    ],
+)
+def unit(session, install_grpc_gcp, install_grpc, install_async_rest):
     """Run the unit test suite."""
-    default(session)
 
-
-@nox.session(python=PYTHON_VERSIONS)
-def unit_w_prerelease_deps(session):
-    """Run the unit test suite."""
-    default(session, prerelease=True)
-
-
-@nox.session(python=PYTHON_VERSIONS)
-def unit_grpc_gcp(session):
-    """
-    Run the unit test suite with grpcio-gcp installed.
-    `grpcio-gcp` doesn't support protobuf 4+.
-    Remove extra `grpcgcp` when protobuf 3.x is dropped.
-    https://github.com/googleapis/python-api-core/issues/594
-    """
-    constraints_path = str(
-        CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
+    # `grpcio-gcp` doesn't support protobuf 4+.
+    # Remove extra `grpcgcp` when protobuf 3.x is dropped.
+    # https://github.com/googleapis/python-api-core/issues/594
+    if install_grpc_gcp:
+        constraints_path = str(
+            CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
+        )
+        # Install grpcio-gcp
+        session.install("-e", ".[grpcgcp]", "-c", constraints_path)
+        # Install protobuf < 4.0.0
+        session.install("protobuf<4.0.0")
+
+    default(
+        session=session,
+        install_grpc=install_grpc,
+        install_async_rest=install_async_rest,
     )
-    # Install grpcio-gcp
-    session.install("-e", ".[grpcgcp]", "-c", constraints_path)
-    # Install protobuf < 4.0.0
-    session.install("protobuf<4.0.0")
-
-    default(session)
-
-
-@nox.session(python=PYTHON_VERSIONS)
-def unit_wo_grpc(session):
-    """Run the unit test suite w/o grpcio installed"""
-    default(session, install_grpc=False)
 
 
-@nox.session(python=PYTHON_VERSIONS)
-def unit_w_async_rest_extra(session):
-    """Run the unit test suite with the `async_rest` extra"""
-    default(session, install_async_rest=True)
+@nox.session(python=DEFAULT_PYTHON_VERSION)
+def prerelease_deps(session):
+    """Run the unit test suite."""
+    default(session, prerelease=True)
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)