tests: unit tests pass w/o environ vars (#207)

Closes: #206

Author: tseaver

tests/unit/test_client.py

@@ -1844,7 +1844,7 @@ def test_conformance_post_policy(test_data):
  in_data = test_data["policyInput"]
  timestamp = datetime.datetime.strptime(in_data["timestamp"], "%Y-%m-%dT%H:%M:%SZ")
 
- client = Client(credentials=_DUMMY_CREDENTIALS)
+ client = Client(credentials=_DUMMY_CREDENTIALS, project="PROJECT")
 
  # mocking time functions
  with mock.patch("google.cloud.storage._signing.NOW", return_value=timestamp):