fix: strip trailing _ from field mask paths (#228)

google/api_core/protobuf_helpers.py

@@ -357,6 +357,13 @@ def _field_mask_helper(original, modified, current=""):
 
 
 def _get_path(current, name):
+    # gapic-generator-python appends underscores to field names
+    # that collide with python keywords.
+    # `_` is stripped away as it is not possible to
+    # natively define a field with a trailing underscore in protobuf.
+    # APIs will reject field masks if fields have trailing underscores.
+    # See https://github.com/googleapis/python-api-core/issues/227
+    name = name.rstrip("_")
     if not current:
         return name
     return "%s.%s" % (current, name)

noxfile.py

@@ -98,9 +98,10 @@ def default(session):
     ]
     pytest_args.extend(session.posargs)
 
-    # Inject AsyncIO content, if version >= 3.6.
+    # Inject AsyncIO content and proto-plus, if version >= 3.6.
+    # proto-plus is needed for a field mask test in test_protobuf_helpers.py
     if _greater_or_equal_than_36(session.python):
-        session.install("asyncmock", "pytest-asyncio")
+        session.install("asyncmock", "pytest-asyncio", "proto-plus")
 
         pytest_args.append("--cov=tests.asyncio")
         pytest_args.append(os.path.join("tests", "asyncio"))

tests/unit/test_protobuf_helpers.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import sys
+
 import pytest
 
 from google.api import http_pb2
@@ -472,3 +474,45 @@ def test_field_mask_different_level_diffs():
         "alpha",
         "red",
     ]
+
+
+@pytest.mark.skipif(
+    sys.version_info.major == 2,
+    reason="Field names with trailing underscores can only be created"
+    "through proto-plus, which is Python 3 only.",
+)
+def test_field_mask_ignore_trailing_underscore():
+    import proto
+
+    class Foo(proto.Message):
+        type_ = proto.Field(proto.STRING, number=1)
+        input_config = proto.Field(proto.STRING, number=2)
+
+    modified = Foo(type_="bar", input_config="baz")
+
+    assert sorted(protobuf_helpers.field_mask(None, Foo.pb(modified)).paths) == [
+        "input_config",
+        "type",
+    ]
+
+
+@pytest.mark.skipif(
+    sys.version_info.major == 2,
+    reason="Field names with trailing underscores can only be created"
+    "through proto-plus, which is Python 3 only.",
+)
+def test_field_mask_ignore_trailing_underscore_with_nesting():
+    import proto
+
+    class Bar(proto.Message):
+        class Baz(proto.Message):
+            input_config = proto.Field(proto.STRING, number=1)
+
+        type_ = proto.Field(Baz, number=1)
+
+    modified = Bar()
+    modified.type_.input_config = "foo"
+
+    assert sorted(protobuf_helpers.field_mask(None, Bar.pb(modified)).paths) == [
+        "type.input_config",
+    ]