test: add regression tests for chunithm SSS

server/src/lib/score-import/framework/common/score-utils.test.ts

@@ -8,7 +8,7 @@ t.test("#GetGradeForPercent", (t) => {
 	t.equal(
 		GetGradeFromPercent("chunithm", "Single", 101),
 		"SSS",
-		"Should return SSS for the edge case of chunithms 101% == SS."
+		"Should return SSS for the edge case of chunithms 101%."
 	);
 	t.equal(
 		GetGradeFromPercent("iidx", "SP", 100),
@@ -47,6 +47,11 @@ t.test("#GetGradeForPercent", (t) => {
 		"Should return SSS for the edge case of 0% == F (iidx DP)."
 	);
 
+	t.throws(
+		() => GetGradeFromPercent("iidx", "DP", -1),
+		"Should throw if percent is unresolvable."
+	);
+
 	t.end();
 });