test: improve routing parameter assert

gapic/schema/wrappers.py

@@ -30,6 +30,7 @@
 import collections
 import copy
 import dataclasses
+import functools
 import json
 import keyword
 import re
@@ -1035,10 +1036,20 @@ def _to_regex(self, path_template: str) -> Pattern:
         """
         return re.compile(f"^{self._convert_to_regex(path_template)}$")
 
+    # Use caching to avoid repeated computation
+    # TODO(https://github.com/googleapis/gapic-generator-python/issues/2161):
+    # Use `@functools.cache` instead of `@functools.lru_cache` once python 3.8 is dropped.
+    # https://docs.python.org/3/library/functools.html#functools.cache
+    @functools.lru_cache(maxsize=None)
     def to_regex(self) -> Pattern:
         return self._to_regex(self.path_template)
 
     @property
+    # Use caching to avoid repeated computation
+    # TODO(https://github.com/googleapis/gapic-generator-python/issues/2161):
+    # Use `@functools.cache` instead of `@functools.lru_cache` once python 3.8 is dropped.
+    # https://docs.python.org/3/library/functools.html#functools.cache
+    @functools.lru_cache(maxsize=None)
     def key(self) -> Union[str, None]:
         if self.path_template == "":
             return self.field
@@ -1067,6 +1078,69 @@ def try_parse_routing_rule(cls, routing_rule: routing_pb2.RoutingRule) -> Option
         params = [RoutingParameter(x.field, x.path_template) for x in params]
         return cls(params)
 
+    @classmethod
+    def resolve(cls, routing_rule: routing_pb2.RoutingRule, request: Union[dict, str]) -> dict:
+        """Resolves the routing header which should be sent along with the request.
+        The routing header is determined based on the given routing rule and request.
+        See the following link for more information on explicit routing headers:
+        https://google.aip.dev/client-libraries/4222#explicit-routing-headers-googleapirouting
+
+        Args:
+            routing_rule(routing_pb2.RoutingRule): A collection of Routing Parameter specifications
+                defined by `routing_pb2.RoutingRule`.
+                See https://github.com/googleapis/googleapis/blob/cb39bdd75da491466f6c92bc73cd46b0fbd6ba9a/google/api/routing.proto#L391
+            request(Union[dict, str]): The request for which the routine rule should be resolved.
+                The format can be either a dictionary or json string representing the request.
+
+        Returns(dict):
+            A dictionary containing the resolved routing header to the sent along with the given request.
+        """
+
+        def _get_field(request, field_path: str):
+            segments = field_path.split(".")
+
+            # Either json string or dictionary is supported
+            if isinstance(request, str):
+                current = json.loads(request)
+            else:
+                current = request
+
+            # This is to cater for the case where the `field_path` contains a
+            # dot-separated path of field names leading to a field in a sub-message.
+            for x in segments:
+                current = current.get(x, None)
+                # Break if the sub-message does not exist
+                if current is None:
+                    break
+            return current
+
+        header_params = {}
+        # TODO(https://github.com/googleapis/gapic-generator-python/issues/2160): Move this logic to
+        # `google-api-core` so that the shared code can be used in both `wrappers.py` and GAPIC clients
+        # via Jinja templates.
+        for routing_param in routing_rule.routing_parameters:
+            request_field_value = _get_field(request, routing_param.field)
+            # Only resolve the header for routing parameter fields which are populated in the request
+            if request_field_value is not None:
+                # If there is a path_template for a given routing parameter field, the value of the field must match
+                # If multiple `routing_param`s describe the same key
+                # (via the `path_template` field or via the `field` field when
+                # `path_template` is not provided), the "last one wins" rule
+                # determines which parameter gets used. See https://google.aip.dev/client-libraries/4222.
+                routing_parameter_key = routing_param.key
+                if routing_param.path_template:
+                    routing_param_regex = routing_param.to_regex()
+                    regex_match = routing_param_regex.match(
+                        request_field_value
+                    )
+                    if regex_match:
+                        header_params[routing_parameter_key] = regex_match.group(
+                            routing_parameter_key
+                        )
+                else:  # No need to match
+                    header_params[routing_parameter_key] = request_field_value
+        return header_params
+
 
 @dataclasses.dataclass(frozen=True)
 class HttpRule:

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

@@ -414,12 +414,11 @@ def test_{{ method.name|snake_case }}_routing_parameters():
 
         # Establish that the underlying gRPC stub method was called.
         assert len(call.mock_calls) == 1
-        _, args, _ = call.mock_calls[0]
+        _, args, kw = call.mock_calls[0]
         assert args[0] == request
 
-    _, _, kw = call.mock_calls[0]
-    # This test doesn't assert anything useful.
-    assert kw['metadata']
+        expected_headers = {{ method.routing_rule.resolve(method.routing_rule, routing_param.sample_request) }}
+        assert gapic_v1.routing_header.to_grpc_metadata(expected_headers) in kw['metadata']
     {% endfor %}
 {% endif %}
 

tests/unit/schema/wrappers/test_routing.py

@@ -14,6 +14,7 @@
 
 from gapic.schema import wrappers
 
+import json
 import proto
 import pytest
 
@@ -23,31 +24,6 @@ class RoutingTestRequest(proto.Message):
     app_profile_id = proto.Field(proto.STRING, number=2)
 
 
-def resolve(rule, request):
-    """This function performs dynamic header resolution, identical to what's in client.py.j2."""
-
-    def _get_field(request, field_path: str):
-        segments = field_path.split(".")
-        cur = request
-        for x in segments:
-            cur = getattr(cur, x)
-        return cur
-
-    header_params = {}
-    for routing_param in rule.routing_parameters:
-        # This may raise exception (which we show to clients).
-        request_field_value = _get_field(request, routing_param.field)
-        if routing_param.path_template:
-            routing_param_regex = routing_param.to_regex()
-            regex_match = routing_param_regex.match(request_field_value)
-            if regex_match:
-                header_params[routing_param.key] = regex_match.group(
-                    routing_param.key)
-        else:  # No need to match
-            header_params[routing_param.key] = request_field_value
-    return header_params
-
-
 @pytest.mark.parametrize(
     "req, expected",
     [
@@ -63,7 +39,10 @@ def _get_field(request, field_path: str):
 def test_routing_rule_resolve_simple_extraction(req, expected):
     rule = wrappers.RoutingRule(
         [wrappers.RoutingParameter("app_profile_id", "")])
-    assert resolve(rule, req) == expected
+    assert wrappers.RoutingRule.resolve(
+        rule,
+        RoutingTestRequest.to_dict(req)
+    ) == expected
 
 
 @pytest.mark.parametrize(
@@ -82,7 +61,10 @@ def test_routing_rule_resolve_rename_extraction(req, expected):
     rule = wrappers.RoutingRule(
         [wrappers.RoutingParameter("app_profile_id", "{routing_id=**}")]
     )
-    assert resolve(rule, req) == expected
+    assert wrappers.RoutingRule.resolve(
+        rule,
+        RoutingTestRequest.to_dict(req)
+    ) == expected
 
 
 @pytest.mark.parametrize(
@@ -111,7 +93,10 @@ def test_routing_rule_resolve_field_match(req, expected):
             ),
         ]
     )
-    assert resolve(rule, req) == expected
+    assert wrappers.RoutingRule.resolve(
+        rule,
+        RoutingTestRequest.to_dict(req)
+    ) == expected
 
 
 @pytest.mark.parametrize(
@@ -135,6 +120,9 @@ def test_routing_rule_resolve_field_match(req, expected):
                 wrappers.RoutingParameter(
                     "table_name", "projects/*/{instance_id=instances/*}/**"
                 ),
+                wrappers.RoutingParameter(
+                    "doesnotexist", "projects/*/{instance_id=instances/*}/**"
+                ),
             ],
             RoutingTestRequest(
                 table_name="projects/100/instances/200/tables/300"),
@@ -144,7 +132,15 @@ def test_routing_rule_resolve_field_match(req, expected):
 )
 def test_routing_rule_resolve(routing_parameters, req, expected):
     rule = wrappers.RoutingRule(routing_parameters)
-    got = resolve(rule, req)
+    got = wrappers.RoutingRule.resolve(
+        rule, RoutingTestRequest.to_dict(req)
+    )
+    assert got == expected
+
+    rule = wrappers.RoutingRule(routing_parameters)
+    got = wrappers.RoutingRule.resolve(
+        rule, json.dumps(RoutingTestRequest.to_dict(req))
+    )
     assert got == expected