build(python): exit with success status if no samples found (#234)

Source-Link: googleapis/synthtool@53ea389
Post-Processor: gcr.io/repo-automation-bots/owlbot-python:latest@sha256:e1793a23ae0ee9aafb2e3a53b564a351f74790dbe3c2d75f8fc3b8c43e5c036c

Author: gcf-owl-bot[bot]

.github/.OwlBot.lock.yaml

@@ -1,3 +1,3 @@
 docker:
   image: gcr.io/repo-automation-bots/owlbot-python:latest
-  digest: sha256:99d90d097e4a4710cc8658ee0b5b963f4426d0e424819787c3ac1405c9a26719
+  digest: sha256:e1793a23ae0ee9aafb2e3a53b564a351f74790dbe3c2d75f8fc3b8c43e5c036c

.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
 

samples/to_dataframe/noxfile.py

@@ -226,7 +226,7 @@ def py(session: nox.sessions.Session) -> None:
 
 
 def _get_repo_root() -> Optional[str]:
-    """Returns the root folder of the project."""
+    """ Returns the root folder of the project. """
     # Get root of this repository. Assume we don't have directories nested deeper than 10 items.
     p = Path(os.getcwd())
     for i in range(10):