diff --git a/lib/common/tests/scores/Makefile.am b/lib/common/tests/scores/Makefile.am
index 0e7aa87da6..395415ffee 100644
--- a/lib/common/tests/scores/Makefile.am
+++ b/lib/common/tests/scores/Makefile.am
@@ -1,21 +1,22 @@
 #
 # Copyright 2020-2022 the Pacemaker project contributors
 #
 # The version control history for this file may have further details.
 #
 # This source code is licensed under the GNU General Public License version 2
 # or later (GPLv2+) WITHOUT ANY WARRANTY.
 #
 
 AM_CPPFLAGS = -I$(top_srcdir)/include -I$(top_builddir)/include -I$(top_srcdir)/lib/common
 LDADD = $(top_builddir)/lib/common/libcrmcommon.la -lcmocka
 
 include $(top_srcdir)/mk/tap.mk
 
 # Add "_test" to the end of all test program names to simplify .gitignore.
 check_PROGRAMS =		\
 	char2score_test		\
+	pcmk__add_scores_test	\
 	score2char_stack_test	\
 	score2char_test
 
 TESTS = $(check_PROGRAMS)
diff --git a/lib/common/tests/scores/pcmk__add_scores_test.c b/lib/common/tests/scores/pcmk__add_scores_test.c
new file mode 100644
index 0000000000..bf7f0cf956
--- /dev/null
+++ b/lib/common/tests/scores/pcmk__add_scores_test.c
@@ -0,0 +1,85 @@
+/*
+ * Copyright 2022 the Pacemaker project contributors
+ *
+ * The version control history for this file may have further details.
+ *
+ * This source code is licensed under the GNU Lesser General Public License
+ * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
+ */
+
+#include <crm_internal.h>
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <setjmp.h>
+#include <cmocka.h>
+
+static void
+score1_minus_inf(void **state)
+{
+    assert_int_equal(pcmk__add_scores(-CRM_SCORE_INFINITY, -CRM_SCORE_INFINITY), -CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(-CRM_SCORE_INFINITY, -1), -CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(-CRM_SCORE_INFINITY, 0), -CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(-CRM_SCORE_INFINITY, 1), -CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(-CRM_SCORE_INFINITY, CRM_SCORE_INFINITY), -CRM_SCORE_INFINITY);
+}
+
+static void
+score2_minus_inf(void **state)
+{
+    assert_int_equal(pcmk__add_scores(-1, -CRM_SCORE_INFINITY), -CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(0, -CRM_SCORE_INFINITY), -CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(1, -CRM_SCORE_INFINITY), -CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(CRM_SCORE_INFINITY, -CRM_SCORE_INFINITY), -CRM_SCORE_INFINITY);
+}
+
+static void
+score1_pos_inf(void **state)
+{
+    assert_int_equal(pcmk__add_scores(CRM_SCORE_INFINITY, CRM_SCORE_INFINITY), CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(CRM_SCORE_INFINITY, -1), CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(CRM_SCORE_INFINITY, 0), CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(CRM_SCORE_INFINITY, 1), CRM_SCORE_INFINITY);
+}
+
+static void
+score2_pos_inf(void **state)
+{
+    assert_int_equal(pcmk__add_scores(-1, CRM_SCORE_INFINITY), CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(0, CRM_SCORE_INFINITY), CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(1, CRM_SCORE_INFINITY), CRM_SCORE_INFINITY);
+}
+
+static void
+result_infinite(void **state)
+{
+    assert_int_equal(pcmk__add_scores(INT_MAX, INT_MAX), CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(INT_MIN, INT_MIN), -CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(2000000, 50), CRM_SCORE_INFINITY);
+    assert_int_equal(pcmk__add_scores(-4000000, 50), -CRM_SCORE_INFINITY);
+}
+
+static void
+result_finite(void **state)
+{
+    assert_int_equal(pcmk__add_scores(0, 0), 0);
+    assert_int_equal(pcmk__add_scores(0, 100), 100);
+    assert_int_equal(pcmk__add_scores(200, 0), 200);
+    assert_int_equal(pcmk__add_scores(200, -50), 150);
+}
+
+int main(int argc, char **argv)
+{
+    const struct CMUnitTest tests[] = {
+        cmocka_unit_test(score1_minus_inf),
+        cmocka_unit_test(score2_minus_inf),
+        cmocka_unit_test(score1_pos_inf),
+        cmocka_unit_test(score2_pos_inf),
+        cmocka_unit_test(result_infinite),
+        cmocka_unit_test(result_finite),
+    };
+
+    cmocka_set_message_output(CM_OUTPUT_TAP);
+    return cmocka_run_group_tests(tests, NULL, NULL);
+}