+static void test_path_join(void) {
+
+#define test_join(root, path, rest, expected) { \
+ _cleanup_free_ char *z = NULL; \
+ z = path_join(root, path, rest); \
+ assert_se(streq(z, expected)); \
+ }
+
+ test_join("/root", "/a/b", "/c", "/root/a/b/c");
+ test_join("/root", "a/b", "c", "/root/a/b/c");
+ test_join("/root", "/a/b", "c", "/root/a/b/c");
+ test_join("/root", "/", "c", "/root//c");
+ test_join("/root", "/", NULL, "/root/");
+
+ test_join(NULL, "/a/b", "/c", "/a/b/c");
+ test_join(NULL, "a/b", "c", "a/b/c");
+ test_join(NULL, "/a/b", "c", "/a/b/c");
+ test_join(NULL, "/", "c", "//c");
+ test_join(NULL, "/", NULL, "/");
+}
+