I've added a test suite for the helper functions in examples/utils/example_helpers.py.

This includes tests for:
- `get_printable_datetime`: checks for string return type and ISO format.
- `get_image_bytes_from_url`: checks for bytes return type, exception handling for invalid URLs, and correct image download using a mock.

I also confirmed that the Google Ads API version is already v19 by default.

Author: google-labs-jules[bot]

examples/utils/tests/.gitkeep

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+# This file is intentionally left blank.
+# It is used to ensure that the directory is tracked by git.

examples/utils/tests/test_example_helpers.py

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+import unittest
+from unittest.mock import patch, MagicMock
+from datetime import datetime
+import requests # Required for requests.exceptions.RequestException
+from examples.utils.example_helpers import get_printable_datetime, get_image_bytes_from_url
+
+class TestGetPrintableDatetime(unittest.TestCase): # Renamed for clarity
+
+    def test_get_printable_datetime_returns_string(self):
+        """Tests that get_printable_datetime returns a string."""
+        self.assertIsInstance(get_printable_datetime(), str)
+
+    def test_get_printable_datetime_iso_format(self):
+        """Tests that get_printable_datetime returns a string in ISO format."""
+        datetime_str = get_printable_datetime()
+        # Attempt to parse the string to ensure it's in ISO format.
+        # datetime.fromisoformat() will raise a ValueError if not.
+        try:
+            datetime.fromisoformat(datetime_str)
+        except ValueError:
+            self.fail(f"'{datetime_str}' is not a valid ISO format datetime string.")
+
+class TestGetImageBytesFromUrl(unittest.TestCase):
+
+    @patch('requests.get')
+    def test_returns_bytes_for_valid_url(self, mock_requests_get):
+        """Tests that the function returns bytes for a valid URL."""
+        sample_bytes = b'sampleimagedata'
+        mock_response = MagicMock()
+        mock_response.content = sample_bytes
+        mock_requests_get.return_value = mock_response
+
+        result = get_image_bytes_from_url("http://example.com/image.jpg")
+        self.assertIsInstance(result, bytes)
+        self.assertEqual(result, sample_bytes)
+        mock_requests_get.assert_called_once_with("http://example.com/image.jpg")
+
+    @patch('requests.get')
+    def test_raises_exception_for_invalid_url(self, mock_requests_get):
+        """Tests that the function raises an exception for an invalid URL."""
+        mock_requests_get.side_effect = requests.exceptions.RequestException("Test error")
+
+        with self.assertRaises(requests.exceptions.RequestException):
+            get_image_bytes_from_url("http://invalid-url-that-does-not-exist.com/image.png")
+        mock_requests_get.assert_called_once_with("http://invalid-url-that-does-not-exist.com/image.png")
+
+    @patch('requests.get')
+    def test_correctly_downloads_image(self, mock_requests_get):
+        """Tests that the function correctly 'downloads' image bytes from a valid URL."""
+        expected_bytes = b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\x00\x00\x01\x00\x00\x00\x01\x08\x06\x00\x00\x00\x1f\x15\xc4\x89'
+        mock_response = MagicMock()
+        mock_response.content = expected_bytes
+        mock_requests_get.return_value = mock_response
+
+        actual_bytes = get_image_bytes_from_url("http://example.com/realimage.png")
+        self.assertEqual(actual_bytes, expected_bytes)
+        mock_requests_get.assert_called_once_with("http://example.com/realimage.png")
+
+
+if __name__ == '__main__':
+    unittest.main()