p2p/tracker: add test file

p2p/tracker/tracker_test.go

@@ -0,0 +1,64 @@
+// Copyright 2026 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package tracker
+
+import (
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/metrics"
+	"github.com/ethereum/go-ethereum/p2p"
+)
+
+// This checks that metrics gauges for pending requests are be decremented when a
+// Tracker is stopped.
+func TestMetricsOnStop(t *testing.T) {
+	metrics.Enable()
+
+	cap := p2p.Cap{Name: "test", Version: 1}
+	tr := New(cap, "peer1", time.Minute)
+
+	// Track some requests with different ReqCodes.
+	var id uint64
+	for i := 0; i < 3; i++ {
+		tr.Track(Request{ID: id, ReqCode: 0x01, RespCode: 0x02, Size: 1})
+		id++
+	}
+	for i := 0; i < 5; i++ {
+		tr.Track(Request{ID: id, ReqCode: 0x03, RespCode: 0x04, Size: 1})
+		id++
+	}
+
+	gauge1 := tr.trackedGauge(0x01)
+	gauge2 := tr.trackedGauge(0x03)
+
+	if gauge1.Snapshot().Value() != 3 {
+		t.Fatalf("gauge1 value mismatch: got %d, want 3", gauge1.Snapshot().Value())
+	}
+	if gauge2.Snapshot().Value() != 5 {
+		t.Fatalf("gauge2 value mismatch: got %d, want 5", gauge2.Snapshot().Value())
+	}
+
+	tr.Stop()
+
+	if gauge1.Snapshot().Value() != 0 {
+		t.Fatalf("gauge1 value after stop: got %d, want 0", gauge1.Snapshot().Value())
+	}
+	if gauge2.Snapshot().Value() != 0 {
+		t.Fatalf("gauge2 value after stop: got %d, want 0", gauge2.Snapshot().Value())
+	}
+}