test: add a simple test for the qr printing code

Ideally, we'd read back what we wrote, but that would have been
much more complicated. But just writing stuff is useful to test under
valgrind or manually.

src/test/meson.build

@@ -808,6 +808,10 @@ tests += [
         [['src/test/test-psi-util.c'],
          [],
          []],
+
+        [['src/test/test-qrcode-util.c'],
+         [libshared],
+         [libdl]],
 ]
 
 ############################################################

src/test/test-qrcode-util.c

@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include "locale-util.h"
+#include "main-func.h"
+#include "qrcode-util.h"
+#include "tests.h"
+
+static int run(int argc, char **argv) {
+        int r;
+
+        test_setup_logging(LOG_DEBUG);
+
+        assert_se(setenv("SYSTEMD_COLORS", "1", 1) == 0); /* Force the qrcode to be printed */
+
+        r = print_qrcode(stdout, "This should say \"TEST\"", "TEST");
+        if (r == -EOPNOTSUPP)
+                return log_tests_skipped("not supported");
+        if (r < 0)
+                return log_error_errno(r, "Failed to print QR code: %m");
+        return 0;
+}
+
+DEFINE_MAIN_FUNCTION(run);