fix: resource messages in method response types generate helpers (#629)

Some resource messages are only referenced in method responses, either
directly (the method returns a resource) or indirectly (the resource
is a field for some other message).
These response-resources now generate helper methods in client
classes.

Contains a minor formatting fix in the generated output, a minor fix
in an error message, and a tweak to nox.py to aid interactive debugging.

gapic/schema/api.py

@@ -460,7 +460,7 @@ def __init__(
             else:
                 raise TypeError(
                     f"Unknown type referenced in "
-                    "{self.file_descriptor.name}: '{key}'"
+                    f"{self.file_descriptor.name}: '{key}'"
                 )
 
         # Only generate the service if this is a target file to be generated.

gapic/schema/wrappers.py

@@ -1012,7 +1012,7 @@ def names(self) -> FrozenSet[str]:
     @utils.cached_property
     def resource_messages(self) -> FrozenSet[MessageType]:
         """Returns all the resource message types used in all
-        request fields in the service."""
+        request and response fields in the service."""
         def gen_resources(message):
             if message.resource_path:
                 yield message
@@ -1022,9 +1022,14 @@ def gen_resources(message):
                     yield type_
 
         return frozenset(
-            resource_msg
+            msg
             for method in self.methods.values()
-            for resource_msg in gen_resources(method.input)
+            for msg in chain(
+                gen_resources(method.input),
+                gen_resources(
+                    method.lro.response_type if method.lro else method.output
+                ),
+            )
         )
 
     @utils.cached_property

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

@@ -137,6 +137,7 @@ class {{ service.client_name }}(metaclass={{ service.client_name }}Meta):
         """Parse a {{ message.resource_type|snake_case }} path into its component segments."""
         m = re.match(r"{{ message.path_regex_str }}", path)
         return m.groupdict() if m else {}
+
     {% endfor %} {# resources #}
     {% for resource_msg in service.common_resources|sort(attribute="type_name") -%}
     @staticmethod

noxfile.py

@@ -37,13 +37,18 @@ def unit(session):
 
     session.run(
         "py.test",
-        "-vv",
-        "-n=auto",
-        "--cov=gapic",
-        "--cov-config=.coveragerc",
-        "--cov-report=term",
-        "--cov-report=html",
-        *(session.posargs or [path.join("tests", "unit")]),
+        *(
+            session.posargs
+            or [
+                "-vv",
+                "-n=auto",
+                "--cov=gapic",
+                "--cov-config=.coveragerc",
+                "--cov-report=term",
+                "--cov-report=html",
+                path.join("tests", "unit"),
+            ]
+        ),
     )
 
 

tests/unit/schema/wrappers/test_service.py

@@ -32,6 +32,24 @@
     make_service_with_method_options,
 )
 
+################################
+# Helper Functions
+################################
+
+
+def make_resource_opts(*args):
+    # Resources are labeled via an options extension
+    opts = descriptor_pb2.MessageOptions()
+    opts.Extensions[resource_pb2.resource].pattern.append(
+        "/".join("{{{arg}}}/{arg}" for arg in args)
+    )
+    return opts
+
+
+################################
+# End Helper Functions
+################################
+
 
 def test_service_properties():
     service = make_service(name='ThingDoer')
@@ -162,14 +180,6 @@ def test_module_name():
 
 
 def test_resource_messages():
-    # Resources are labeled via an options extension
-    def make_resource_opts(*args):
-        opts = descriptor_pb2.MessageOptions()
-        opts.Extensions[resource_pb2.resource].pattern.append(
-            "/".join("{{{arg}}}/{arg}" for arg in args)
-        )
-        return opts
-
     # Regular, top level resource
     squid_resource = make_message("Squid", options=make_resource_opts("squid"))
     squid_request = make_message(
@@ -336,3 +346,34 @@ def test_common_resource_patterns():
     assert species_msg.resource_type == "Species"
     assert species_msg.resource_path_args == ["family", "genus", "species"]
     assert species_msg.path_regex_str == '^families/(?P<family>.+?)/genera/(?P<genus>.+?)/species/(?P<species>.+?)$'
+
+
+def test_resource_response():
+    # Top level response resource
+    squid_resource = make_message("Squid", options=make_resource_opts("squid"))
+    squid_request = make_message("CreateSquidRequest")
+
+    # Nested response resource
+    clam_resource = make_message("Clam", options=make_resource_opts("clam"))
+    clam_response = make_message(
+        "CreateClamResponse",
+        fields=(
+            make_field('clam', message=clam_resource),
+        ),
+    )
+    clam_request = make_message("CreateClamRequest")
+
+    mollusc_service = make_service(
+        "MolluscService",
+        methods=(
+            make_method(f"{request.name}", request, response)
+            for request, response in (
+                (squid_request, squid_resource),
+                (clam_request, clam_response),
+            )
+        ),
+    )
+
+    expected = {squid_resource, clam_resource}
+    actual = mollusc_service.resource_messages
+    assert expected == actual