Ensure tests are runnable when standalone (#552)

When we run tests internally that don't invoke the test class, they pass
but don't run the tests.

Our GitHub environment tests them fine but this change ensures they run
in both environments.

tests/test_helpers.py

@@ -12,11 +12,11 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-import pathlib
 import copy
 import collections
 from typing import Union
 
+from absl.testing import absltest
 from absl.testing import parameterized
 
 from google.generativeai import protos
@@ -81,3 +81,7 @@ def test_get_model(self, request_options, expected_timeout, expected_retry):
 
         self.assertEqual(self.observed_timeout[0], expected_timeout)
         self.assertEqual(str(self.observed_retry[0]), str(expected_retry))
+
+
+if __name__ == "__main__":
+    absltest.main()

tests/test_protos.py

@@ -15,6 +15,7 @@
 import pathlib
 import re
 
+from absl.testing import absltest
 from absl.testing import parameterized
 
 ROOT = pathlib.Path(__file__).parent.parent
@@ -32,3 +33,7 @@ def test_check_glm_imports(self):
                     match,
                     msg=f"Bad `glm.` usage, use `genai.protos` instead,\n   in {fpath}",
                 )
+
+
+if __name__ == "__main__":
+    absltest.main()

tests/test_responder.py

@@ -19,8 +19,7 @@
 from absl.testing import parameterized
 from google.generativeai import protos
 from google.generativeai import responder
-import IPython.display
-import PIL.Image
+
 
 HERE = pathlib.Path(__file__).parent
 TEST_PNG_PATH = HERE / "test_img.png"
@@ -250,3 +249,7 @@ def fun(a: annotation):
         cfd = responder.FunctionDeclaration.from_function(fun)
         got = cfd.parameters.properties["a"]
         self.assertEqual(got, expected)
+
+
+if __name__ == "__main__":
+    absltest.main()