test: adds pytest-xdist to speed up processing of CI/CD checks (googleapis#2153)

* experimentation using pytest-xdist

* adds pytest-xdist to nox system session for experimentation

* adds pytest-xdist install AND -n=auto argument

* updates sample noxfiles

* updates pytest version in requirements-test.txt files

* Update samples/notebooks/requirements-test.txt

* Update samples/notebooks/requirements-test.txt

Author: chalmerlowe

noxfile.py

@@ -98,6 +98,7 @@ def default(session, install_extras=True):
         "pytest",
         "google-cloud-testutils",
         "pytest-cov",
+        "pytest-xdist",
         "freezegun",
         "-c",
         constraints_path,
@@ -129,6 +130,7 @@ def default(session, install_extras=True):
     # Run py.test against the unit tests.
     session.run(
         "py.test",
+        "-n=auto",
         "--quiet",
         "-W default::PendingDeprecationWarning",
         "--cov=google/cloud/bigquery",
@@ -224,7 +226,12 @@ def system(session):
 
     # Install all test dependencies, then install local packages in place.
     session.install(
-        "pytest", "psutil", "google-cloud-testutils", "-c", constraints_path
+        "pytest",
+        "psutil",
+        "pytest-xdist",
+        "google-cloud-testutils",
+        "-c",
+        constraints_path,
     )
     if os.environ.get("GOOGLE_API_USE_CLIENT_CERTIFICATE", "") == "true":
         # mTLS test requires pyopenssl and latest google-cloud-storage
@@ -257,6 +264,7 @@ def system(session):
     # Run py.test against the system tests.
     session.run(
         "py.test",
+        "-n=auto",
         "--quiet",
         "-W default::PendingDeprecationWarning",
         os.path.join("tests", "system"),
@@ -310,7 +318,9 @@ def snippets(session):
     )
 
     # Install all test dependencies, then install local packages in place.
-    session.install("pytest", "google-cloud-testutils", "-c", constraints_path)
+    session.install(
+        "pytest", "pytest-xdist", "google-cloud-testutils", "-c", constraints_path
+    )
     session.install("google-cloud-storage", "-c", constraints_path)
     session.install("grpcio", "-c", constraints_path)
 
@@ -326,9 +336,12 @@ def snippets(session):
     # Run py.test against the snippets tests.
     # Skip tests in samples/snippets, as those are run in a different session
     # using the nox config from that directory.
-    session.run("py.test", os.path.join("docs", "snippets.py"), *session.posargs)
+    session.run(
+        "py.test", "-n=auto", os.path.join("docs", "snippets.py"), *session.posargs
+    )
     session.run(
         "py.test",
+        "-n=auto",
         "samples",
         "-W default::PendingDeprecationWarning",
         "--ignore=samples/desktopapp",
@@ -393,6 +406,7 @@ def prerelease_deps(session):
         "google-cloud-testutils",
         "psutil",
         "pytest",
+        "pytest-xdist",
         "pytest-cov",
     )
 
@@ -439,18 +453,21 @@ def prerelease_deps(session):
     # Run all tests, except a few samples tests which require extra dependencies.
     session.run(
         "py.test",
+        "-n=auto",
         "tests/unit",
         "-W default::PendingDeprecationWarning",
     )
 
     session.run(
         "py.test",
+        "-n=auto",
         "tests/system",
         "-W default::PendingDeprecationWarning",
     )
 
     session.run(
         "py.test",
+        "-n=auto",
         "samples/tests",
         "-W default::PendingDeprecationWarning",
     )

samples/desktopapp/requirements-test.txt

@@ -1,3 +1,4 @@
 google-cloud-testutils==1.6.0
 pytest==8.3.5
 mock==5.2.0
+pytest-xdist==3.6.1

samples/geography/requirements-test.txt

@@ -1,2 +1,3 @@
 pytest==8.3.5
 mock==5.2.0
+pytest-xdist==3.6.1

samples/magics/requirements-test.txt

@@ -1,3 +1,4 @@
 google-cloud-testutils==1.6.0
 pytest==8.3.5
 mock==5.2.0
+pytest-xdist==3.6.1

samples/notebooks/requirements-test.txt

@@ -1,3 +1,4 @@
 google-cloud-testutils==1.6.0
 pytest==8.3.5
 mock==5.2.0
+pytest-xdist==3.6.1

samples/snippets/requirements-test.txt

@@ -2,3 +2,4 @@
 google-cloud-testutils==1.6.0
 pytest==8.3.5
 mock==5.2.0
+pytest-xdist==3.6.1