diff --git a/cmd/csaf_downloader/stats_test.go b/cmd/csaf_downloader/stats_test.go
new file mode 100644
index 0000000..69567ab
--- /dev/null
+++ b/cmd/csaf_downloader/stats_test.go
@@ -0,0 +1,112 @@
+// This file is Free Software under the MIT License
+// without warranty, see README.md and LICENSES/MIT.txt for details.
+//
+// SPDX-License-Identifier: MIT
+//
+// SPDX-FileCopyrightText: 2023 German Federal Office for Information Security (BSI) <https://www.bsi.bund.de>
+// Software-Engineering: 2023 Intevation GmbH <https://intevation.de>
+
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"log/slog"
+	"testing"
+)
+
+func TestStatsAdd(t *testing.T) {
+	a := stats{
+		downloadFailed:  2,
+		filenameFailed:  3,
+		schemaFailed:    5,
+		remoteFailed:    7,
+		sha256Failed:    11,
+		sha512Failed:    13,
+		signatureFailed: 17,
+		succeeded:       19,
+	}
+	b := a
+	a.add(&b)
+	b.downloadFailed *= 2
+	b.filenameFailed *= 2
+	b.schemaFailed *= 2
+	b.remoteFailed *= 2
+	b.sha256Failed *= 2
+	b.sha512Failed *= 2
+	b.signatureFailed *= 2
+	b.succeeded *= 2
+	if a != b {
+		t.Fatalf("%v != %v", a, b)
+	}
+}
+
+func TestStatsTotalFailed(t *testing.T) {
+	a := stats{
+		downloadFailed:  2,
+		filenameFailed:  3,
+		schemaFailed:    5,
+		remoteFailed:    7,
+		sha256Failed:    11,
+		sha512Failed:    13,
+		signatureFailed: 17,
+	}
+	sum := a.downloadFailed +
+		a.filenameFailed +
+		a.schemaFailed +
+		a.remoteFailed +
+		a.sha256Failed +
+		a.sha512Failed +
+		a.signatureFailed
+	if got := a.totalFailed(); got != sum {
+		t.Fatalf("got %d expected %d", got, sum)
+	}
+}
+
+func TestStatsLog(t *testing.T) {
+	var out bytes.Buffer
+	h := slog.NewJSONHandler(&out, &slog.HandlerOptions{Level: slog.LevelInfo})
+	orig := slog.Default()
+	defer slog.SetDefault(orig)
+	slog.SetDefault(slog.New(h))
+	a := stats{
+		downloadFailed:  2,
+		filenameFailed:  3,
+		schemaFailed:    5,
+		remoteFailed:    7,
+		sha256Failed:    11,
+		sha512Failed:    13,
+		signatureFailed: 17,
+		succeeded:       19,
+	}
+	a.log()
+	type result struct {
+		Succeeded       int `json:"succeeded"`
+		TotalFailed     int `json:"total_failed"`
+		FilenameFailed  int `json:"filename_failed"`
+		DownloadFailed  int `json:"download_failed"`
+		SchemaFailed    int `json:"schema_failed"`
+		RemoteFailed    int `json:"remote_failed"`
+		SHA256Failed    int `json:"sha256_failed"`
+		SHA512Failed    int `json:"sha512_failed"`
+		SignatureFailed int `json:"signature_failed"`
+	}
+	var got result
+	if err := json.Unmarshal(out.Bytes(), &got); err != nil {
+		t.Fatal(err)
+	}
+	want := result{
+		Succeeded:       a.succeeded,
+		TotalFailed:     a.totalFailed(),
+		FilenameFailed:  a.filenameFailed,
+		DownloadFailed:  a.downloadFailed,
+		SchemaFailed:    a.schemaFailed,
+		RemoteFailed:    a.remoteFailed,
+		SHA256Failed:    a.sha256Failed,
+		SHA512Failed:    a.sha512Failed,
+		SignatureFailed: a.signatureFailed,
+	}
+	if got != want {
+		t.Fatalf("%v != %v", got, want)
+	}
+}