Add temp dir unit test

Author: MatteoPologruto

updater/download_image_test.go

@@ -0,0 +1,45 @@
+// This file is part of arduino-flasher-cli.
+//
+// Copyright 2025 ARDUINO SA (http://www.arduino.cc/)
+//
+// This software is released under the GNU General Public License version 3,
+// which covers the main part of arduino-flasher-cli.
+// The terms of this license can be found at:
+// https://www.gnu.org/licenses/gpl-3.0.en.html
+//
+// You can be released from the requirements of the above licenses by purchasing
+// a commercial license. Buying such a license is mandatory if you want to
+// modify or otherwise use the software for commercial activities involving the
+// Arduino software without disclosing the source code of your own applications.
+// To purchase a commercial license, send an email to license@arduino.cc.
+
+package updater
+
+import (
+	"os"
+	"testing"
+
+	"github.com/arduino/go-paths-helper"
+	"github.com/stretchr/testify/require"
+)
+
+func TestTempDir(t *testing.T) {
+	userCacheDir, err := os.UserCacheDir()
+	require.NoError(t, err)
+
+	defaultTempDir, err := SetTempDir("download-", "")
+	defer func() { _ = defaultTempDir.RemoveAll() }()
+	require.NoError(t, err)
+	require.DirExists(t, defaultTempDir.String())
+	require.Contains(t, defaultTempDir.Base(), "download-")
+	require.Contains(t, defaultTempDir.String(), userCacheDir)
+
+	customTempDir, err := SetTempDir("extract-", ".")
+	defer func() { _ = customTempDir.RemoveAll() }()
+	require.NoError(t, err)
+	require.DirExists(t, customTempDir.String())
+	require.Contains(t, customTempDir.Base(), "extract-")
+	currentDir, err := paths.New(".").Abs()
+	require.NoError(t, err)
+	require.Contains(t, customTempDir.String(), currentDir.String())
+}