test: Add TempDir() helper

src/restic/test/helpers.go

@@ -170,3 +170,21 @@ func RemoveAll(t testing.TB, path string) {
 	ResetReadOnly(t, path)
 	OK(t, os.RemoveAll(path))
 }
+
+// TempDir returns a temporary directory that is removed when cleanup is
+// called, except if TestCleanupTempDirs is set to false.
+func TempDir(t testing.TB) (path string, cleanup func()) {
+	tempdir, err := ioutil.TempDir(TestTempDir, "restic-test-")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return tempdir, func() {
+		if !TestCleanupTempDirs {
+			t.Logf("leaving temporary directory %v used for test", tempdir)
+			return
+		}
+
+		RemoveAll(t, tempdir)
+	}
+}