diff --git a/src/test/meson.build b/src/test/meson.build
index cf060c3bd1b..6c81131c996 100644
--- a/src/test/meson.build
+++ b/src/test/meson.build
@@ -143,6 +143,10 @@ tests += [
           libmount,
           libblkid]],
 
+        [['src/test/test-serialize.c'],
+         [],
+         []],
+
         [['src/test/test-utf8.c'],
          [],
          []],
diff --git a/src/test/test-serialize.c b/src/test/test-serialize.c
new file mode 100644
index 00000000000..59594554119
--- /dev/null
+++ b/src/test/test-serialize.c
@@ -0,0 +1,149 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include "def.h"
+#include "escape.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "log.h"
+#include "serialize.h"
+#include "strv.h"
+#include "tests.h"
+
+#define sixteen(x) x x x x x x x x x x x x x x x x
+#define million(x) sixteen(sixteen(sixteen(sixteen(sixteen(x)))))
+
+#define long_string million("x")
+assert_cc(STRLEN(long_string) == LONG_LINE_MAX);
+
+static void test_serialize_item(void) {
+        _cleanup_(unlink_tempfilep) char fn[] = "/tmp/test-serialize.XXXXXX";
+        _cleanup_fclose_ FILE *f = NULL;
+
+        assert_se(fmkostemp_safe(fn, "r+", &f) == 0);
+        log_info("/* %s (%s) */", __func__, fn);
+
+        assert_se(serialize_item(f, "a", NULL) == 0);
+        assert_se(serialize_item(f, "a", "bbb") == 1);
+        assert_se(serialize_item(f, "a", "bbb") == 1);
+        assert_se(serialize_item(f, "a", long_string) == -EINVAL);
+        assert_se(serialize_item(f, long_string, "a") == -EINVAL);
+        assert_se(serialize_item(f, long_string, long_string) == -EINVAL);
+
+        rewind(f);
+
+        _cleanup_free_ char *line1 = NULL, *line2 = NULL, *line3 = NULL;
+        assert_se(read_line(f, LONG_LINE_MAX, &line1) > 0);
+        assert_se(streq(line1, "a=bbb"));
+        assert_se(read_line(f, LONG_LINE_MAX, &line2) > 0);
+        assert_se(streq(line2, "a=bbb"));
+        assert_se(read_line(f, LONG_LINE_MAX, &line3) == 0);
+        assert_se(streq(line3, ""));
+}
+
+static void test_serialize_item_escaped(void) {
+        _cleanup_(unlink_tempfilep) char fn[] = "/tmp/test-serialize.XXXXXX";
+        _cleanup_fclose_ FILE *f = NULL;
+
+        assert_se(fmkostemp_safe(fn, "r+", &f) == 0);
+        log_info("/* %s (%s) */", __func__, fn);
+
+        assert_se(serialize_item_escaped(f, "a", NULL) == 0);
+        assert_se(serialize_item_escaped(f, "a", "bbb") == 1);
+        assert_se(serialize_item_escaped(f, "a", "bbb") == 1);
+        assert_se(serialize_item_escaped(f, "a", long_string) == -EINVAL);
+        assert_se(serialize_item_escaped(f, long_string, "a") == -EINVAL);
+        assert_se(serialize_item_escaped(f, long_string, long_string) == -EINVAL);
+
+        rewind(f);
+
+        _cleanup_free_ char *line1 = NULL, *line2 = NULL, *line3 = NULL;
+        assert_se(read_line(f, LONG_LINE_MAX, &line1) > 0);
+        assert_se(streq(line1, "a=bbb"));
+        assert_se(read_line(f, LONG_LINE_MAX, &line2) > 0);
+        assert_se(streq(line2, "a=bbb"));
+        assert_se(read_line(f, LONG_LINE_MAX, &line3) == 0);
+        assert_se(streq(line3, ""));
+}
+
+static void test_serialize_usec(void) {
+        _cleanup_(unlink_tempfilep) char fn[] = "/tmp/test-serialize.XXXXXX";
+        _cleanup_fclose_ FILE *f = NULL;
+
+        assert_se(fmkostemp_safe(fn, "r+", &f) == 0);
+        log_info("/* %s (%s) */", __func__, fn);
+
+        assert_se(serialize_usec(f, "usec1", USEC_INFINITY) == 0);
+        assert_se(serialize_usec(f, "usec2", 0) == 1);
+        assert_se(serialize_usec(f, "usec3", USEC_INFINITY-1) == 1);
+
+        rewind(f);
+
+        _cleanup_free_ char *line1 = NULL, *line2 = NULL;
+        usec_t x;
+
+        assert_se(read_line(f, LONG_LINE_MAX, &line1) > 0);
+        assert_se(streq(line1, "usec2=0"));
+        assert_se(deserialize_usec(line1 + 6, &x) == 0);
+        assert_se(x == 0);
+
+        assert_se(read_line(f, LONG_LINE_MAX, &line2) > 0);
+        assert_se(startswith(line2, "usec3="));
+        assert_se(deserialize_usec(line2 + 6, &x) == 0);
+        assert_se(x == USEC_INFINITY-1);
+}
+
+static void test_serialize_strv(void) {
+        _cleanup_(unlink_tempfilep) char fn[] = "/tmp/test-serialize.XXXXXX";
+        _cleanup_fclose_ FILE *f = NULL;
+
+        char **strv = STRV_MAKE("a", "b", "foo foo",
+                                "nasty1 \"",
+                                "\"nasty2 ",
+                                "nasty3 '",
+                                "\"nasty4 \"",
+                                "nasty5\n",
+                                "\nnasty5\nfoo=bar",
+                                "\nnasty5\nfoo=bar");
+
+        assert_se(fmkostemp_safe(fn, "r+", &f) == 0);
+        log_info("/* %s (%s) */", __func__, fn);
+
+        assert_se(serialize_strv(f, "strv1", NULL) == 0);
+        assert_se(serialize_strv(f, "strv2", STRV_MAKE_EMPTY) == 0);
+        assert_se(serialize_strv(f, "strv3", strv) == 1);
+        assert_se(serialize_strv(f, "strv4", STRV_MAKE(long_string)) == -EINVAL);
+
+        rewind(f);
+
+        _cleanup_strv_free_ char **strv2 = NULL;
+        for (;;) {
+                _cleanup_free_ char *line = NULL;
+                int r;
+
+                r = read_line(f, LONG_LINE_MAX, &line);
+                if (r == 0)
+                        break;
+                assert_se(r > 0);
+
+                const char *t = startswith(line, "strv3=");
+                assert_se(t);
+
+                char *un;
+                assert_se(cunescape(t, 0, &un) >= 0);
+                assert_se(strv_consume(&strv2, un) >= 0);
+        }
+
+        assert_se(strv_equal(strv, strv2));
+}
+
+int main(int argc, char *argv[]) {
+        test_setup_logging(LOG_INFO);
+
+        test_serialize_item();
+        test_serialize_item_escaped();
+        test_serialize_usec();
+        test_serialize_strv();
+
+        return EXIT_SUCCESS;
+}