feat(stats): add bounded path and hash-width analytics (#159)

internal/cache/paths_test.go

@@ -0,0 +1,48 @@
+// Copyright 2026 Beacon Contributors
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+package cache
+
+import (
+	"context"
+	"slices"
+	"testing"
+	"time"
+
+	"github.com/MeshCore-Beacon/beacon-server/internal/api"
+)
+
+type pathStatsReader struct {
+	api.Reader
+	calls int64
+}
+
+func (r *pathStatsReader) GetPathStats(context.Context, time.Time, time.Time, []string) (*api.PathStats, error) {
+	r.calls++
+	return &api.PathStats{Receptions: r.calls}, nil
+}
+
+func TestPathCacheSeparatesWindowAndRegion(t *testing.T) {
+	c, mr := newTestClient(t)
+	inner := &pathStatsReader{}
+	r := NewCachedReader(inner, c, CacheTTLs{Stats: time.Minute})
+	for _, tc := range []struct {
+		iatas              []string
+		since, until, want int64
+	}{
+		{nil, 0, 10, 1}, {[]string{}, 0, 10, 1}, {[]string{""}, 0, 10, 2}, {[]string{"YVR"}, 0, 10, 3},
+		{[]string{"YVR", "YYJ"}, 0, 10, 4}, {[]string{"YYJ", "YVR", "YYJ"}, 0, 10, 4},
+		{nil, 1, 10, 5}, {nil, 0, 11, 6}, {nil, 0, 10, 1},
+	} {
+		before := slices.Clone(tc.iatas)
+		got, err := r.GetPathStats(context.Background(), time.UnixMilli(tc.since), time.UnixMilli(tc.until), tc.iatas)
+		if err != nil || got.Receptions != tc.want || !slices.Equal(before, tc.iatas) {
+			t.Fatalf("%+v: %+v %v", tc, got, err)
+		}
+	}
+	mr.FastForward(time.Minute)
+	got, err := r.GetPathStats(context.Background(), time.UnixMilli(0), time.UnixMilli(10), nil)
+	if err != nil || got.Receptions != 7 {
+		t.Fatalf("expiry: %+v %v", got, err)
+	}
+}