feat: Automatically populate uuid4 fields

gapic/ads-templates/%namespace/%name/%version/%sub/services/%service/client.py.j2

@@ -6,6 +6,7 @@ from collections import OrderedDict
 import os
 import re
 from typing import Callable, Dict, Mapping, MutableMapping, MutableSequence, Optional, {% if service.any_server_streaming %}Iterable, {% endif %}{% if service.any_client_streaming %}Iterator, {% endif %}Sequence, Tuple, Type, Union, cast
+import uuid
 {% if service.any_deprecated %}
 import warnings
 {% endif %}
@@ -473,6 +474,27 @@ class {{ service.client_name }}(metaclass={{ service.client_name }}Meta):
         )
         {% endif %}
 
+{#
+    Automatically populate uuid4 fields according to AIP-4235
+    (https://google.aip.dev/client-libraries/4235) if the
+    field satisfies either of:
+    - The field supports explicit presence and has not been set by the user
+    - The field doesn't support explicit presence, and its value is the empty
+      string (i.e. the default value)
+#}
+{% with method_settings = api.all_method_settings.get(method.meta.address.proto) %}
+{% if method_settings is not none %}
+{% for auto_populated_field in method_settings.auto_populated_fields %}
+    {% if method.input.fields[auto_populated_field].proto3_optional %}
+        if not request.HasField({{ auto_populated_field }}):
+    {% else %}
+        if not request.{{ auto_populated_field }}:
+    {% endif %}
+            request.{{ auto_populated_field }} = str(uuid.uuid4())
+{% endfor %}
+{% endif %}{# if method_settings is not none #}
+{% endwith %}{# method_settings #}
+
         # Send the request.
         {%+ if not method.void %}response = {% endif %}rpc(
             {% if not method.client_streaming %}

gapic/ads-templates/tests/unit/gapic/%name_%version/%sub/test_%service.py.j2

@@ -3,6 +3,7 @@
 {% block content %}
 
 import os
+import re
 # try/except added for compatibility with python < 3.8
 try:
     from unittest import mock
@@ -519,8 +520,20 @@ def test_{{ method_name }}(request_type, transport: str = 'grpc'):
     )
 
     # Everything is optional in proto3 as far as the runtime is concerned,
-    # and we are mocking out the actual API, so just send an empty request.
+    # and we are mocking out the actual API.
     request = request_type()
+
+    # Set uuid4 fields so that they are not automatically popoulated. 
+    {% with method_settings = api.all_method_settings.get(method.meta.address.proto) %}
+    {% if method_settings is not none %}
+    {% for auto_populated_field in method_settings.auto_populated_fields %}
+    if isinstance(request, dict):
+        request['{{ auto_populated_field }}'] = "str_value"
+    else:
+        request.{{ auto_populated_field }} = "str_value"
+    {% endfor %}
+    {% endif %}{# if method_settings is not none #}
+    {% endwith %}{# method_settings #}
     {% if method.client_streaming %}
     requests = [request]
     {% endif %}
@@ -629,6 +642,16 @@ def test_{{ method_name }}_empty_call():
         {% if method.client_streaming %}
         assert next(args[0]) == request
         {% else %}
+{% with method_settings = api.all_method_settings.get(method.meta.address.proto) %}
+{% if method_settings is not none %}
+{% for auto_populated_field in method_settings.auto_populated_fields %}
+        # Ensure that the uuid4 field is set according to AIP 4235
+        assert re.match(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].{{ auto_populated_field }})
+        # clear UUID field so that the check below succeeds
+        args[0].{{ auto_populated_field }} = ""
+{% endfor %}
+{% endif %}{# if method_settings is not none #}
+{% endwith %}{# method_settings #}
         assert args[0] == {{ method.input.ident }}()
         {% endif %}
 {% endif %}

gapic/templates/%namespace/%name_%version/%sub/services/%service/_client_macros.j2

@@ -183,6 +183,8 @@
         )
         {% endif %} {# method.explicit_routing #}
 
+{{ auto_populate_uuid4_fields(api, method) }}
+
         # Validate the universe domain.
         self._validate_universe_domain()
 
@@ -265,3 +267,26 @@
 
 {% macro define_extended_operation_subclass(extended_operation) %}
 {% endmacro %}
+
+{% macro auto_populate_uuid4_fields(api, method) %}
+{# 
+    Automatically populate uuid4 fields according to AIP-4235
+    (https://google.aip.dev/client-libraries/4235) if the
+    field satisfies either of:
+    - The field supports explicit presence and has not been set by the user
+    - The field doesn't support explicit presence, and its value is the empty
+      string (i.e. the default value)
+#}
+{% with method_settings = api.all_method_settings.get(method.meta.address.proto) %}
+{% if method_settings is not none %}
+{% for auto_populated_field in method_settings.auto_populated_fields %}
+    {% if method.input.fields[auto_populated_field].proto3_optional %}
+        if not request.HasField({{ auto_populated_field }}):
+    {% else %}
+        if not request.{{ auto_populated_field }}:
+    {% endif %}
+            request.{{ auto_populated_field }} = str(uuid.uuid4())
+{% endfor %}
+{% endif %}{# if method_settings is not none #}
+{% endwith %}{# method_settings #}
+{% endmacro %}

gapic/templates/%namespace/%name_%version/%sub/services/%service/async_client.py.j2

@@ -1,11 +1,13 @@
 {% extends "_base.py.j2" %}
 
 {% block content %}
+{% import "%namespace/%name_%version/%sub/services/%service/_client_macros.j2" as macros %}
 
 from collections import OrderedDict
 import functools
 import re
 from typing import Dict, Mapping, MutableMapping, MutableSequence, Optional, {% if service.any_server_streaming %}AsyncIterable, Awaitable, {% endif %}{% if service.any_client_streaming %}AsyncIterator, {% endif %}Sequence, Tuple, Type, Union
+import uuid
 {% if service.any_deprecated %}
 import warnings
 {% endif %}
@@ -386,6 +388,8 @@ class {{ service.async_client_name }}:
         )
         {% endif %}
 
+{{ macros.auto_populate_uuid4_fields(api, method) }}
+
         # Validate the universe domain.
         self._client._validate_universe_domain()
 

gapic/templates/%namespace/%name_%version/%sub/services/%service/client.py.j2

@@ -10,6 +10,7 @@ import functools
 import os
 import re
 from typing import Dict, Mapping, MutableMapping, MutableSequence, Optional, {% if service.any_server_streaming %}Iterable, {% endif %}{% if service.any_client_streaming %}Iterator, {% endif %}Sequence, Tuple, Type, Union, cast
+import uuid
 import warnings
 
 {% set package_path = api.naming.module_namespace|join('.') + "." + api.naming.versioned_module_name %}

gapic/templates/tests/unit/gapic/%name_%version/%sub/test_%service.py.j2

@@ -4,6 +4,7 @@
 {% import "tests/unit/gapic/%name_%version/%sub/test_macros.j2" as test_macros %}
 
 import os
+import re
 # try/except added for compatibility with python < 3.8
 try:
     from unittest import mock
@@ -849,10 +850,10 @@ def test_{{ service.client_name|snake_case }}_create_channel_credentials_file(cl
 
 {% for method in service.methods.values() if 'grpc' in opts.transport %}{# method_name #}
 {% if method.extended_lro %}
-{{ test_macros.grpc_required_tests(method, service, full_extended_lro=True) }}
+{{ test_macros.grpc_required_tests(method, service, api, full_extended_lro=True) }}
 
 {% endif %}
-{{ test_macros.grpc_required_tests(method, service) }}
+{{ test_macros.grpc_required_tests(method, service, api) }}
 {% endfor %} {# method in methods for grpc #}
 
 {% for method in service.methods.values() if 'rest' in opts.transport %}

gapic/templates/tests/unit/gapic/%name_%version/%sub/test_macros.j2

@@ -1,4 +1,4 @@
-{% macro grpc_required_tests(method, service, full_extended_lro=False) %}
+{% macro grpc_required_tests(method, service, api, full_extended_lro=False) %}
 {% with method_name = method.safe_name|snake_case + "_unary" if method.extended_lro and not full_extended_lro else method.safe_name|snake_case, method_output = method.extended_lro.operation_type if method.extended_lro and not full_extended_lro else method.output %}
 @pytest.mark.parametrize("request_type", [
   {{ method.input.ident }},
@@ -11,8 +11,19 @@ def test_{{ method_name }}(request_type, transport: str = 'grpc'):
     )
 
     # Everything is optional in proto3 as far as the runtime is concerned,
-    # and we are mocking out the actual API, so just send an empty request.
+    # and we are mocking out the actual API.
     request = request_type()
+    # Set uuid4 fields so that they are not automatically popoulated. 
+    {% with method_settings = api.all_method_settings.get(method.meta.address.proto) %}
+    {% if method_settings is not none %}
+    {% for auto_populated_field in method_settings.auto_populated_fields %}
+    if isinstance(request, dict):
+        request['{{ auto_populated_field }}'] = "str_value"
+    else:
+        request.{{ auto_populated_field }} = "str_value"
+    {% endfor %}
+    {% endif %}{# if method_settings is not none #}
+    {% endwith %}{# method_settings #}
     {% if method.client_streaming %}
     requests = [request]
     {% endif %}
@@ -58,7 +69,15 @@ def test_{{ method_name }}(request_type, transport: str = 'grpc'):
         {% if method.client_streaming %}
         assert next(args[0]) == request
         {% else %}
-        assert args[0] == {{ method.input.ident }}()
+        request = {{ method.input.ident }}()
+        {% with method_settings = api.all_method_settings.get(method.meta.address.proto) %}
+        {% if method_settings is not none %}
+        {% for auto_populated_field in method_settings.auto_populated_fields %}
+        request.{{ auto_populated_field }} = "str_value"
+        {% endfor %}
+        {% endif %}{# if method_settings is not none #}
+        {% endwith %}{# method_settings #}
+        assert args[0] == request
         {% endif %}
 
     # Establish that the response is the type that we expect.
@@ -119,11 +138,77 @@ def test_{{ method_name }}_empty_call():
         {% if method.client_streaming %}
         assert next(args[0]) == request
         {% else %}
+        {% with method_settings = api.all_method_settings.get(method.meta.address.proto) %}
+        {% if method_settings is not none %}
+        {% for auto_populated_field in method_settings.auto_populated_fields %}
+        # Ensure that the uuid4 field is set according to AIP 4235
+        assert re.match(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].{{ auto_populated_field }})
+        # clear UUID field so that the check below succeeds
+        args[0].{{ auto_populated_field }} = ""
+        {% endfor %}
+        {% endif %}{# if method_settings is not none #}
+        {% endwith %}{# method_settings #}
         assert args[0] == {{ method.input.ident }}()
         {% endif %}
 {% endif %}
 
 {% if not full_extended_lro %}
+{% if not method.client_streaming %}
+@pytest.mark.asyncio
+async def test_{{ method_name }}_empty_call_async():
+    # This test is a coverage failsafe to make sure that totally empty calls,
+    # i.e. request == None and no flattened fields passed, work.
+    client = {{ service.async_client_name }}(
+        credentials=ga_credentials.AnonymousCredentials(),
+        transport='grpc_asyncio',
+    )
+
+    # Mock the actual call within the gRPC stub, and fake the request.
+    with mock.patch.object(
+            type(client.transport.{{ method.transport_safe_name|snake_case }}),
+            '__call__') as call:
+        # Designate an appropriate return value for the call.
+        {% if method.void %}
+        call.return_value = grpc_helpers_async.FakeUnaryUnaryCall(None)
+        {% elif method.lro %}
+        call.return_value = grpc_helpers_async.FakeUnaryUnaryCall(
+            operations_pb2.Operation(name='operations/spam')
+        )
+        {% elif not method.client_streaming and method.server_streaming %}
+        call.return_value = mock.Mock(aio.UnaryStreamCall, autospec=True)
+        call.return_value.read = mock.AsyncMock(side_effect=[{{ method.output.ident }}()])
+        {% elif method.client_streaming and method.server_streaming %}
+        call.return_value = mock.Mock(aio.StreamStreamCall, autospec=True)
+        call.return_value.read = mock.AsyncMock(side_effect=[{{ method.output.ident }}()])
+        {% else %}
+        call.return_value ={{ '' }}
+            {%- if not method.client_streaming and not method.server_streaming -%}
+                grpc_helpers_async.FakeUnaryUnaryCall
+            {%- else -%}
+                grpc_helpers_async.FakeStreamUnaryCall
+            {%- endif -%}({{ method.output.ident }}(
+            {% for field in method.output.fields.values() | rejectattr('message') %}{% if not field.oneof or field.proto3_optional %}
+            {{ field.name }}={{ field.mock_value }},
+            {% endif %}
+            {% endfor %}
+        ))
+        {% endif %}
+        response = await client.{{ method_name }}()
+        call.assert_called()
+        _, args, _ = call.mock_calls[0]
+        {% with method_settings = api.all_method_settings.get(method.meta.address.proto) %}
+        {% if method_settings is not none %}
+        {% for auto_populated_field in method_settings.auto_populated_fields %}
+        # Ensure that the uuid4 field is set according to AIP 4235
+        assert re.match(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].{{ auto_populated_field }})
+        # clear UUID field so that the check below succeeds
+        args[0].{{ auto_populated_field }} = ""
+        {% endfor %}
+        {% endif %}{# if method_settings is not none #}
+        {% endwith %}{# method_settings #}
+        assert args[0] == {{ method.input.ident }}()
+{% endif %}
+
 @pytest.mark.asyncio
 async def test_{{ method_name }}_async(transport: str = 'grpc_asyncio', request_type={{ method.input.ident }}):
     client = {{ service.async_client_name }}(
@@ -132,8 +217,19 @@ async def test_{{ method_name }}_async(transport: str = 'grpc_asyncio', request_
     )
 
     # Everything is optional in proto3 as far as the runtime is concerned,
-    # and we are mocking out the actual API, so just send an empty request.
+    # and we are mocking out the actual API.
     request = request_type()
+    # Set uuid4 fields so that they are not automatically popoulated. 
+    {% with method_settings = api.all_method_settings.get(method.meta.address.proto) %}
+    {% if method_settings is not none %}
+    {% for auto_populated_field in method_settings.auto_populated_fields %}
+    if isinstance(request, dict):
+        request['{{ auto_populated_field }}'] = "str_value"
+    else:
+        request.{{ auto_populated_field }} = "str_value"
+    {% endfor %}
+    {% endif %}{# if method_settings is not none #}
+    {% endwith %}{# method_settings #}
     {% if method.client_streaming %}
     requests = [request]
     {% endif %}
@@ -182,7 +278,15 @@ async def test_{{ method_name }}_async(transport: str = 'grpc_asyncio', request_
         {% if method.client_streaming %}
         assert next(args[0]) == request
         {% else %}
-        assert args[0] == {{ method.input.ident }}()
+        request = {{ method.input.ident }}()
+        {% with method_settings = api.all_method_settings.get(method.meta.address.proto) %}
+        {% if method_settings is not none %}
+        {% for auto_populated_field in method_settings.auto_populated_fields %}
+        request.{{ auto_populated_field }} = "str_value"
+        {% endfor %}
+        {% endif %}{# if method_settings is not none #}
+        {% endwith %}{# method_settings #}
+        assert args[0] == request
         {% endif %}
 
     # Establish that the response is the type that we expect.

tests/system/test_unary.py

@@ -14,6 +14,7 @@
 
 import os
 import pytest
+import re
 
 from google.api_core import exceptions
 from google.rpc import code_pb2
@@ -24,15 +25,48 @@
 def test_unary_with_request_object(echo):
     response = echo.echo(showcase.EchoRequest(
         content='The hail in Wales falls mainly on the snails.',
+        request_id='some_value',
     ))
     assert response.content == 'The hail in Wales falls mainly on the snails.'
+    assert response.request_id == 'some_value'
+
+    # Repeat the same test but this time without `request_id`` set
+    # The `request_id` field should be automatically populated with
+    # a UUID4 value if it is not set.
+    # See https://google.aip.dev/client-libraries/4235
+    response = echo.echo(showcase.EchoRequest(
+        content='The hail in Wales falls mainly on the snails.',
+    ))
+    assert response.content == 'The hail in Wales falls mainly on the snails.'
+    # Ensure that the uuid4 field is set according to AIP 4235
+    re.match(
+        r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}",
+        response.request_id,
+    )
+    assert len(response.request_id) == 36
 
 
 def test_unary_with_dict(echo):
+    response = echo.echo({
+        'content': 'The hail in Wales falls mainly on the snails.',
+        'request_id': 'some_value',
+    })
+    assert response.content == 'The hail in Wales falls mainly on the snails.'
+    assert response.request_id == 'some_value'
+
+    # Repeat the same test but this time without `request_id`` set
+    # The `request_id` field should be automatically populated with
+    # a UUID4 value if it is not set.
+    # See https://google.aip.dev/client-libraries/4235
     response = echo.echo({
         'content': 'The hail in Wales falls mainly on the snails.',
     })
     assert response.content == 'The hail in Wales falls mainly on the snails.'
+    re.match(
+        r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}",
+        response.request_id,
+    )
+    assert len(response.request_id) == 36
 
 
 def test_unary_error(echo):