feat: update templates to permit enum aliases (googleapis#809)

Certain APIs like RecommendationEngine use multiple enum variant
monikers to reference the same value. Achieving this in protos
requires explicit support from proto-plus and the generated surface.

Hand testing indicates compliance.

Bump the min proto-plus version for generated clients.

Author: software-dov

gapic/ads-templates/%namespace/%name/%version/%sub/types/_enum.py.j2

@@ -1,5 +1,8 @@
 class {{ enum.name }}({{ p }}.Enum):
     r"""{{ enum.meta.doc|rst(indent=4) }}"""
+    {% if enum.enum_pb.HasField("options") -%}
+     _pb_options = {{ enum.options_dict }}
+    {% endif -%}
     {% for enum_value in enum.values -%}
     {{ enum_value.name }} = {{ enum_value.number }}
     {% endfor -%}

gapic/ads-templates/setup.py.j2

@@ -19,7 +19,7 @@ setuptools.setup(
         'google-api-core >= 1.22.2, < 2.0.0dev',
         'googleapis-common-protos >= 1.5.8',
         'grpcio >= 1.10.0',
-        'proto-plus >= 1.4.0',
+        'proto-plus >= 1.15.0',
     {%- if api.requires_package(('google', 'iam', 'v1')) %}
         'grpc-google-iam-v1',
     {%- endif %}

gapic/schema/wrappers.py

@@ -39,6 +39,7 @@
 from google.api import resource_pb2
 from google.api_core import exceptions      # type: ignore
 from google.protobuf import descriptor_pb2  # type: ignore
+from google.protobuf.json_format import MessageToDict  # type: ignore
 
 from gapic import utils
 from gapic.schema import metadata
@@ -413,7 +414,7 @@ def get_field(self, *field_path: str,
         # Get the first field in the path.
         first_field = field_path[0]
         cursor = self.fields[first_field +
-            ('_' if first_field in utils.RESERVED_NAMES else '')]
+                             ('_' if first_field in utils.RESERVED_NAMES else '')]
 
         # Base case: If this is the last field in the path, return it outright.
         if len(field_path) == 1:
@@ -536,6 +537,18 @@ def with_context(self, *, collisions: FrozenSet[str]) -> 'EnumType':
             meta=self.meta.with_context(collisions=collisions),
         )
 
+    @property
+    def options_dict(self) -> Dict:
+        """Return the EnumOptions (if present) as a dict.
+
+        This is a hack to support a pythonic structure representation for
+        the generator templates.
+        """
+        return MessageToDict(
+            self.enum_pb.options,
+            preserving_proto_field_name=True
+        )
+
 
 @dataclasses.dataclass(frozen=True)
 class PythonType:
@@ -869,7 +882,7 @@ def paged_result_field(self) -> Optional[Field]:
 
         # The request must have page_token and next_page_token as they keep track of pages
         for source, source_type, name in ((self.input, str, 'page_token'),
-                           (self.output, str, 'next_page_token')):
+                                          (self.output, str, 'next_page_token')):
             field = source.fields.get(name, None)
             if not field or field.type != source_type:
                 return None

gapic/templates/%namespace/%name_%version/%sub/types/_enum.py.j2

@@ -1,5 +1,8 @@
 class {{ enum.name }}({{ p }}.Enum):
     r"""{{ enum.meta.doc|rst(indent=4) }}"""
+    {% if enum.enum_pb.HasField("options") -%}
+     _pb_options = {{ enum.options_dict }}
+    {% endif -%}
     {% for enum_value in enum.values -%}
     {{ enum_value.name }} = {{ enum_value.number }}
     {% endfor -%}

gapic/templates/setup.py.j2

@@ -28,7 +28,7 @@ setuptools.setup(
     install_requires=(
         'google-api-core[grpc] >= 1.22.2, < 2.0.0dev',
         'libcst >= 0.2.5',
-        'proto-plus >= 1.4.0',
+        'proto-plus >= 1.15.0',
     {%- if api.requires_package(('google', 'iam', 'v1')) or opts.add_iam_methods %}
         'grpc-google-iam-v1',
     {%- endif %}

test_utils/test_utils.py

@@ -290,6 +290,7 @@ def make_enum(
     module: str = 'baz',
     values: typing.Tuple[str, int] = (),
     meta: metadata.Metadata = None,
+    options: desc.EnumOptions = None,
 ) -> wrappers.EnumType:
     enum_value_pbs = [
         desc.EnumValueDescriptorProto(name=i[0], number=i[1])
@@ -298,6 +299,7 @@ def make_enum(
     enum_pb = desc.EnumDescriptorProto(
         name=name,
         value=enum_value_pbs,
+        options=options,
     )
     return wrappers.EnumType(
         enum_pb=enum_pb,

tests/unit/schema/wrappers/test_enums.py

@@ -37,6 +37,18 @@ def test_enum_value_properties():
 
 
 def test_enum_ident():
-    message = make_enum('Baz', package='foo.v1', module='bar')
-    assert str(message.ident) == 'bar.Baz'
-    assert message.ident.sphinx == 'foo.v1.bar.Baz'
+    enum = make_enum('Baz', package='foo.v1', module='bar')
+    assert str(enum.ident) == 'bar.Baz'
+    assert enum.ident.sphinx == 'foo.v1.bar.Baz'
+
+
+def test_enum_options_dict():
+    cephalopod = make_enum("Cephalopod", package="animalia.v1",
+                     module="mollusca", options={"allow_alias": True})
+    assert isinstance(cephalopod.enum_pb.options, descriptor_pb2.EnumOptions)
+    assert cephalopod.options_dict == {"allow_alias": True}
+
+    bivalve = make_enum("Bivalve", package="animalia.v1",
+                     module="mollusca")
+    assert isinstance(bivalve.enum_pb.options, descriptor_pb2.EnumOptions)
+    assert bivalve.options_dict == {}