fix: don't use stale session in rest transport (#1291)

* fix: don't use stale session in rest transport

* add test

Author: parthea

packages/gapic-generator/gapic/ads-templates/%namespace/%name/%version/%sub/services/%service/transports/rest.py.j2

@@ -129,7 +129,6 @@ class {{service.name}}RestTransport({{service.name}}Transport):
 
     It sends JSON representations of protocol buffers over HTTP/1.1
     """
-    _STUBS: Dict[str, {{service.name}}RestStub] = {}
 
 
     {# TODO(yon-mg): handle mtls stuff if that is relevant for rest transport #}
@@ -399,13 +398,9 @@ class {{service.name}}RestTransport({{service.name}}Transport):
     def {{method.transport_safe_name | snake_case}}(self) -> Callable[
             [{{method.input.ident}}],
             {{method.output.ident}}]:
-        stub = self._STUBS.get("{{method.transport_safe_name | snake_case}}")
-        if not stub:
-            stub = self._STUBS["{{method.transport_safe_name | snake_case}}"] = self._{{method.name}}(self._session, self._host, self._interceptor)
-
         # The return type is fine, but mypy isn't sophisticated enough to determine what's going on here.
         # In C++ this would require a dynamic_cast
-        return stub # type: ignore
+        return self._{{method.name}}(self._session, self._host, self._interceptor) # type: ignore
 
     {% endfor %}
 

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

@@ -1941,6 +1941,28 @@ def test_{{ service.name|snake_case }}_host_with_port(transport_name):
     )
     {% endwith %}
 
+{% if 'rest' in opts.transport %}
+@pytest.mark.parametrize("transport_name", [
+    "rest",
+])
+def test_{{ service.name|snake_case }}_client_transport_session_collision(transport_name):
+    creds1 = ga_credentials.AnonymousCredentials()
+    creds2 = ga_credentials.AnonymousCredentials()
+    client1 = {{ service.client_name }}(
+        credentials=creds1,
+        transport=transport_name,
+    )
+    client2 = {{ service.client_name }}(
+        credentials=creds2,
+        transport=transport_name,
+    )
+    {% for method in service.methods.values() %}
+    session1 = client1.transport.{{ method.transport_safe_name|snake_case }}._session
+    session2 = client2.transport.{{ method.transport_safe_name|snake_case }}._session
+    assert session1 != session2
+    {% endfor %}
+{% endif -%}
+
 {% if 'grpc' in opts.transport %}
 def test_{{ service.name|snake_case }}_grpc_transport_channel():
     channel = grpc.secure_channel('http://localhost/', grpc.local_channel_credentials())

packages/gapic-generator/gapic/templates/%namespace/%name_%version/%sub/services/%service/transports/rest.py.j2

@@ -129,7 +129,6 @@ class {{service.name}}RestTransport({{service.name}}Transport):
 
     It sends JSON representations of protocol buffers over HTTP/1.1
     """
-    _STUBS: Dict[str, {{service.name}}RestStub] = {}
 
 
     {# TODO(yon-mg): handle mtls stuff if that is relevant for rest transport #}
@@ -399,13 +398,9 @@ class {{service.name}}RestTransport({{service.name}}Transport):
     def {{method.transport_safe_name|snake_case}}(self) -> Callable[
             [{{method.input.ident}}],
             {{method.output.ident}}]:
-        stub = self._STUBS.get("{{method.transport_safe_name|snake_case}}")
-        if not stub:
-            stub = self._STUBS["{{method.transport_safe_name|snake_case}}"] = self._{{method.name}}(self._session, self._host, self._interceptor)
-
         # The return type is fine, but mypy isn't sophisticated enough to determine what's going on here.
         # In C++ this would require a dynamic_cast
-        return stub # type: ignore
+        return self._{{method.name}}(self._session, self._host, self._interceptor) # type: ignore
 
     {% endfor %}
 

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

@@ -1031,6 +1031,28 @@ def test_{{ service.name|snake_case }}_host_with_port(transport_name):
     )
     {% endwith %}
 
+{% if 'rest' in opts.transport %}
+@pytest.mark.parametrize("transport_name", [
+    "rest",
+])
+def test_{{ service.name|snake_case }}_client_transport_session_collision(transport_name):
+    creds1 = ga_credentials.AnonymousCredentials()
+    creds2 = ga_credentials.AnonymousCredentials()
+    client1 = {{ service.client_name }}(
+        credentials=creds1,
+        transport=transport_name,
+    )
+    client2 = {{ service.client_name }}(
+        credentials=creds2,
+        transport=transport_name,
+    )
+    {% for method in service.methods.values() %}
+    session1 = client1.transport.{{ method.transport_safe_name|snake_case }}._session
+    session2 = client2.transport.{{ method.transport_safe_name|snake_case }}._session
+    assert session1 != session2
+    {% endfor %}
+{% endif -%}
+
 {% if 'grpc' in opts.transport %}
 def test_{{ service.name|snake_case }}_grpc_transport_channel():
     channel = grpc.secure_channel('http://localhost/', grpc.local_channel_credentials())