1 files changed, 82 insertions, 0 deletions
diff --git a/test/core/util/fake_stats_plugin.cc b/test/core/util/fake_stats_plugin.cc
new file mode 100644
index 0000000000..f8819461da
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+++ b/test/core/util/fake_stats_plugin.cc
@@ -0,0 +1,82 @@
+// Copyright 2023 The gRPC Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "test/core/util/fake_stats_plugin.h"
+
+#include "src/core/lib/config/core_configuration.h"
+
+namespace grpc_core {
+
+class FakeStatsClientFilter : public ChannelFilter {
+ public:
+  static const grpc_channel_filter kFilter;
+
+  static absl::StatusOr<FakeStatsClientFilter> Create(
+      const ChannelArgs& /*args*/, ChannelFilter::Args /*filter_args*/);
+
+  ArenaPromise<ServerMetadataHandle> MakeCallPromise(
+      CallArgs call_args, NextPromiseFactory next_promise_factory) override;
+
+ private:
+  explicit FakeStatsClientFilter(
+      FakeClientCallTracerFactory* fake_client_call_tracer_factory);
+  FakeClientCallTracerFactory* const fake_client_call_tracer_factory_;
+};
+
+const grpc_channel_filter FakeStatsClientFilter::kFilter =
+    MakePromiseBasedFilter<FakeStatsClientFilter, FilterEndpoint::kClient>(
+        "fake_stats_client");
+
+absl::StatusOr<FakeStatsClientFilter> FakeStatsClientFilter::Create(
+    const ChannelArgs& args, ChannelFilter::Args /*filter_args*/) {
+  auto* fake_client_call_tracer_factory =
+      args.GetPointer<FakeClientCallTracerFactory>(
+          GRPC_ARG_INJECT_FAKE_CLIENT_CALL_TRACER_FACTORY);
+  GPR_ASSERT(fake_client_call_tracer_factory != nullptr);
+  return FakeStatsClientFilter(fake_client_call_tracer_factory);
+}
+
+ArenaPromise<ServerMetadataHandle> FakeStatsClientFilter::MakeCallPromise(
+    CallArgs call_args, NextPromiseFactory next_promise_factory) {
+  FakeClientCallTracer* client_call_tracer =
+      fake_client_call_tracer_factory_->CreateFakeClientCallTracer();
+  if (client_call_tracer != nullptr) {
+    auto* call_context = GetContext<grpc_call_context_element>();
+    call_context[GRPC_CONTEXT_CALL_TRACER_ANNOTATION_INTERFACE].value =
+        client_call_tracer;
+    call_context[GRPC_CONTEXT_CALL_TRACER_ANNOTATION_INTERFACE].destroy =
+        nullptr;
+  }
+  return next_promise_factory(std::move(call_args));
+}
+
+FakeStatsClientFilter::FakeStatsClientFilter(
+    FakeClientCallTracerFactory* fake_client_call_tracer_factory)
+    : fake_client_call_tracer_factory_(fake_client_call_tracer_factory) {}
+
+void RegisterFakeStatsPlugin() {
+  CoreConfiguration::RegisterBuilder(
+      [](CoreConfiguration::Builder* builder) mutable {
+        builder->channel_init()
+            ->RegisterFilter(GRPC_CLIENT_CHANNEL,
+                             &FakeStatsClientFilter::kFilter)
+            .If([](const ChannelArgs& args) {
+              return args.GetPointer<FakeClientCallTracerFactory>(
+                         GRPC_ARG_INJECT_FAKE_CLIENT_CALL_TRACER_FACTORY) !=
+                     nullptr;
+            });
+      });
+}
+
+}  // namespace grpc_core