From 2282decdbc0e33d31140312b7d46da968a81e247 Mon Sep 17 00:00:00 2001
From: Abhishek Ranjan <aranjans@google.com>
Date: Wed, 10 Apr 2024 15:24:04 +0530
Subject: [PATCH] Added test

---
 test/stats_test.go | 122 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)
 create mode 100644 test/stats_test.go

diff --git a/test/stats_test.go b/test/stats_test.go
new file mode 100644
index 00000000000..cefbf108e80
--- /dev/null
+++ b/test/stats_test.go
@@ -0,0 +1,122 @@
+/*
+ *
+ * Copyright 2024 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.
+ *
+ */
+
+package test
+
+import (
+	"context"
+	"net"
+	"sync"
+	"testing"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/interop"
+	testgrpc "google.golang.org/grpc/interop/grpc_testing"
+	"google.golang.org/grpc/peer"
+	"google.golang.org/grpc/stats"
+)
+
+// TestPeerForClientStatsHandler tests the scenario where stats handler
+// (having peer as part of its struct) has peer enriched as part of
+// stream context.
+func (s) TestPeerForClientStatsHandler(t *testing.T) {
+	spy := &handlerSpy{}
+
+	// Start server.
+	l, err := net.Listen("tcp", "localhost:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	grpcServer := grpc.NewServer()
+	testgrpc.RegisterTestServiceServer(grpcServer, interop.NewTestServer())
+	errCh := make(chan error)
+	go func() {
+		errCh <- grpcServer.Serve(l)
+	}()
+	t.Cleanup(func() {
+		grpcServer.Stop()
+		if err := <-errCh; err != nil {
+			t.Error(err)
+		}
+	})
+
+	// Create client with stats handler and do some calls.
+	conn, err := grpc.NewClient(
+		l.Addr().String(),
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithStatsHandler(spy))
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() {
+		if err := conn.Close(); err != nil {
+			t.Error(err)
+		}
+	})
+
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	client := testgrpc.NewTestServiceClient(conn)
+	interop.DoEmptyUnaryCall(ctx, client)
+	interop.DoLargeUnaryCall(ctx, client)
+	interop.DoClientStreaming(ctx, client)
+	interop.DoServerStreaming(ctx, client)
+	interop.DoPingPong(ctx, client)
+
+	// Assert if peer is populated for each stats type.
+	for _, callbackArgs := range spy.Args {
+		if callbackArgs.Peer == nil {
+			switch callbackArgs.RPCStats.(type) {
+			case *stats.Begin:
+				continue
+			case *stats.PickerUpdated:
+				continue
+			default:
+			}
+			t.Errorf("peer not populated for: %T", callbackArgs.RPCStats)
+		}
+	}
+}
+
+type peerStats struct {
+	RPCStats stats.RPCStats
+	Peer     *peer.Peer
+}
+
+type handlerSpy struct {
+	Args []peerStats
+	mu   sync.Mutex
+}
+
+func (h *handlerSpy) TagRPC(ctx context.Context, info *stats.RPCTagInfo) context.Context {
+	return ctx
+}
+
+func (h *handlerSpy) HandleRPC(ctx context.Context, rs stats.RPCStats) {
+	h.mu.Lock()
+	p, _ := peer.FromContext(ctx)
+	h.Args = append(h.Args, peerStats{rs, p})
+	h.mu.Unlock()
+}
+
+func (h *handlerSpy) TagConn(ctx context.Context, info *stats.ConnTagInfo) context.Context {
+	return ctx
+}
+
+func (h *handlerSpy) HandleConn(context.Context, stats.ConnStats) {}