diff --git a/internal/lsp/cmd/serve_test.go b/internal/lsp/cmd/serve_test.go
new file mode 100644
index 00000000000..ad3f8b2336b
--- /dev/null
+++ b/internal/lsp/cmd/serve_test.go
@@ -0,0 +1,86 @@
+package cmd
+
+import (
+	"context"
+	"io"
+	"regexp"
+	"testing"
+	"time"
+
+	"golang.org/x/tools/internal/jsonrpc2"
+	"golang.org/x/tools/internal/lsp/protocol"
+	"golang.org/x/tools/internal/telemetry/log"
+)
+
+type fakeServer struct {
+	protocol.Server
+	client protocol.Client
+}
+
+func (s *fakeServer) DidOpen(ctx context.Context, params *protocol.DidOpenTextDocumentParams) error {
+	// Our instrumentation should cause this message to be logged back to the LSP
+	// client.
+	log.Print(ctx, "ping")
+	return nil
+}
+
+type fakeClient struct {
+	protocol.Client
+
+	logs chan string
+}
+
+func (c *fakeClient) LogMessage(ctx context.Context, params *protocol.LogMessageParams) error {
+	c.logs <- params.Message
+	return nil
+}
+
+func TestClientLogging(t *testing.T) {
+	server := &fakeServer{}
+	client := &fakeClient{logs: make(chan string)}
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	// Bind our fake client and server.
+	// sReader and sWriter read from and write to the server. cReader and cWriter
+	// read from and write to the client.
+	sReader, sWriter := io.Pipe()
+	cReader, cWriter := io.Pipe()
+	close := func() {
+		failOnErr := func(err error) {
+			if err != nil {
+				t.Fatal(err)
+			}
+		}
+		failOnErr(sReader.Close())
+		failOnErr(cReader.Close())
+		failOnErr(sWriter.Close())
+		failOnErr(cWriter.Close())
+	}
+	defer close()
+	serverStream := jsonrpc2.NewStream(sReader, cWriter)
+	// The returned client dispatches to the client, but it is already stored
+	// in the context by NewServer, so we can ignore it.
+	serverCtx, serverConn, _ := protocol.NewServer(ctx, serverStream, server)
+	serverConn.AddHandler(&handler{})
+	clientStream := jsonrpc2.NewStream(cReader, sWriter)
+	clientCtx, clientConn, serverDispatch := protocol.NewClient(ctx, clientStream, client)
+
+	go clientConn.Run(clientCtx)
+	go serverConn.Run(serverCtx)
+	serverDispatch.DidOpen(ctx, &protocol.DidOpenTextDocumentParams{})
+
+	select {
+	case got := <-client.logs:
+		want := "ping"
+		matched, err := regexp.MatchString(want, got)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if !matched {
+			t.Errorf("got log %q, want a log containing %q", got, want)
+		}
+	case <-time.After(1 * time.Second):
+		t.Error("timeout waiting for client log")
+	}
+}