Add a repr method for ClientOptions (#9849)

diff --git a/google/api_core/client_options.py b/google/api_core/client_options.py
index 1144d2f..137043f 100644
--- a/google/api_core/client_options.py
+++ b/google/api_core/client_options.py
@@ -50,6 +50,9 @@
     def __init__(self, api_endpoint=None):
         self.api_endpoint = api_endpoint
 
+    def __repr__(self):
+        return "ClientOptions: " + repr(self.__dict__)
+
 
 def from_dict(options):
     """Construct a client options object from a dictionary.
diff --git a/tests/unit/test_client_options.py b/tests/unit/test_client_options.py
index 14cae9f..952adfc 100644
--- a/tests/unit/test_client_options.py
+++ b/tests/unit/test_client_options.py
@@ -34,3 +34,9 @@
         client_options.from_dict(
             {"api_endpoint": "foo.googleapis.com", "bad_arg": "1234"}
         )
+
+
+def test_repr():
+    options = client_options.ClientOptions(api_endpoint="foo.googleapis.com")
+
+    assert repr(options) == "ClientOptions: {'api_endpoint': 'foo.googleapis.com'}"