build(python): exit with success status if no samples found

.github/.OwlBot.lock.yaml

@@ -1,3 +1,3 @@
 docker:
   image: gcr.io/repo-automation-bots/owlbot-python:latest
-  digest: sha256:58c7342b0bccf85028100adaa3d856cb4a871c22ca9c01960d996e66c40548ce
+  digest: sha256:e1793a23ae0ee9aafb2e3a53b564a351f74790dbe3c2d75f8fc3b8c43e5c036c

.kokoro/samples/python3.9/common.cfg

@@ -0,0 +1,40 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+# Build logs will be here
+action {
+  define_artifacts {
+    regex: "**/*sponge_log.xml"
+  }
+}
+
+# Specify which tests to run
+env_vars: {
+    key: "RUN_TESTS_SESSION"
+    value: "py-3.9"
+}
+
+# Declare build specific Cloud project.
+env_vars: {
+    key: "BUILD_SPECIFIC_GCLOUD_PROJECT"
+    value: "python-docs-samples-tests-py39"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-cloud-core/.kokoro/test-samples.sh"
+}
+
+# Configure the docker image for kokoro-trampoline.
+env_vars: {
+    key: "TRAMPOLINE_IMAGE"
+    value: "gcr.io/cloud-devrel-kokoro-resources/python-samples-testing-docker"
+}
+
+# Download secrets for samples
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/python-docs-samples"
+
+# Download trampoline resources.
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
+
+# Use the trampoline script to run in docker.
+build_file: "python-cloud-core/.kokoro/trampoline.sh"

.kokoro/samples/python3.9/continuous.cfg

@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}

.kokoro/samples/python3.9/periodic-head.cfg

@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-pubsub/.kokoro/test-samples-against-head.sh"
+}

.kokoro/samples/python3.9/periodic.cfg

@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "False"
+}

.kokoro/samples/python3.9/presubmit.cfg

@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}

.kokoro/test-samples-impl.sh

@@ -20,9 +20,9 @@ set -eo pipefail
 # Enables `**` to include files nested inside sub-folders
 shopt -s globstar
 
-# Exit early if samples directory doesn't exist
-if [ ! -d "./samples" ]; then
-  echo "No tests run. `./samples` not found"
+# Exit early if samples don't exist
+if ! find samples -name 'requirements.txt' | grep -q .; then
+  echo "No tests run. './samples/**/requirements.txt' not found"
   exit 0
 fi
 

.pre-commit-config.yaml

@@ -16,7 +16,7 @@
 # See https://pre-commit.com/hooks.html for more hooks
 repos:
 -   repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v3.4.0
+    rev: v4.0.1
     hooks:
     -   id: trailing-whitespace
     -   id: end-of-file-fixer

CONTRIBUTING.rst

@@ -22,7 +22,7 @@ In order to add a feature:
   documentation.
 
 - The feature must work fully on the following CPython versions:
-  3.6, 3.7, 3.8 and 3.9 on both UNIX and Windows.
+  2.7, 3.6, 3.7, 3.8 and 3.9 on both UNIX and Windows.
 
 - The feature must not add unnecessary dependencies (where
   "unnecessary" is of course subjective, but new dependencies should
@@ -68,15 +68,12 @@ Using ``nox``
 We use `nox <https://nox.readthedocs.io/en/latest/>`__ to instrument our tests.
 
 - To test your changes, run unit tests with ``nox``::
+    $ nox -s unit
 
-    $ nox -s unit-2.7
-    $ nox -s unit-3.8
-    $ ...
+- To run a single unit test::
 
-- Args to pytest can be passed through the nox command separated by a `--`. For
-  example, to run a single test::
+    $ nox -s unit-3.9 -- -k <name of test>
 
-    $ nox -s unit-3.8 -- -k <name of test>
 
   .. note::
 
@@ -143,18 +140,16 @@ Running System Tests
 - To run system tests, you can execute::
 
    # Run all system tests
-   $ nox -s system-3.8
-   $ nox -s system-2.7
+   $ nox -s system
 
    # Run a single system test
    $ nox -s system-3.8 -- -k <name of test>
 
 
   .. note::
 
-      System tests are only configured to run under Python 2.7 and
-      Python 3.8. For expediency, we do not run them in older versions
-      of Python 3.
+      System tests are only configured to run under Python 2.7 and 3.8.
+      For expediency, we do not run them in older versions of Python 3.
 
   This alone will not run the tests. You'll need to change some local
   auth settings and change some configuration in your project to
@@ -202,11 +197,13 @@ Supported Python Versions
 
 We support:
 
+-  `Python 2.7`_
 -  `Python 3.6`_
 -  `Python 3.7`_
 -  `Python 3.8`_
 -  `Python 3.9`_
 
+.. _Python 2.7: https://docs.python.org/2.7/
 .. _Python 3.6: https://docs.python.org/3.6/
 .. _Python 3.7: https://docs.python.org/3.7/
 .. _Python 3.8: https://docs.python.org/3.8/
@@ -218,8 +215,8 @@ Supported versions can be found in our ``noxfile.py`` `config`_.
 .. _config: https://github.com/googleapis/python-cloud-core/blob/master/noxfile.py
 
 
-We also explicitly decided to support Python 3 beginning with version
-3.6. Reasons for this include:
+We also explicitly decided to support Python 3 beginning with version 2.7.
+Reasons for this include:
 
 -  Encouraging use of newest versions of Python 3
 -  Taking the lead of `prominent`_ open-source `projects`_