test: add explicit test cases for cpu_set_add() and cpu_set_add_range()

cpu_set_add_range() is used in parse_cpu_set(), hence already tested.
But it is better to test these functions explicitly.

For CID#1611787 and CID#1611788, that should be false-positive.

src/shared/cpu-set-util.c

@@ -179,7 +179,7 @@ int cpu_set_add_set(CPUSet *c, const CPUSet *src) {
         return 1;
 }
 
-static int cpu_set_add_range(CPUSet *c, size_t start, size_t end) {
+int cpu_set_add_range(CPUSet *c, size_t start, size_t end) {
         int r;
 
         assert(c);

src/shared/cpu-set-util.h

@@ -24,6 +24,7 @@ void cpu_set_done(CPUSet *c);
 int cpu_set_realloc(CPUSet *c, size_t n);
 int cpu_set_add(CPUSet *c, size_t i);
 int cpu_set_add_set(CPUSet *c, const CPUSet *src);
+int cpu_set_add_range(CPUSet *c, size_t start, size_t end);
 int cpu_set_add_all(CPUSet *c);
 
 char* cpu_set_to_string(const CPUSet *c);

src/test/test-cpu-set-util.c

@@ -262,4 +262,25 @@ TEST(print_cpu_alloc_size) {
         log_info("CPU_ALLOC_SIZE(8191) = %zu", CPU_ALLOC_SIZE(8191));
 }
 
+TEST(cpu_set_add) {
+        _cleanup_(cpu_set_done) CPUSet c = {};
+
+        for (size_t i = 0; i < 8192; i++)
+                ASSERT_OK(cpu_set_add(&c, 8191));
+
+        ASSERT_ERROR(cpu_set_add(&c, 8192), ERANGE);
+        ASSERT_ERROR(cpu_set_add(&c, SIZE_MAX), ERANGE);
+}
+
+TEST(cpu_set_add_range) {
+        _cleanup_(cpu_set_done) CPUSet c = {};
+
+        ASSERT_ERROR(cpu_set_add_range(&c, 0, 8192), ERANGE);
+        ASSERT_ERROR(cpu_set_add_range(&c, 0, SIZE_MAX), ERANGE);
+        ASSERT_SIGNAL(cpu_set_add_range(&c, 100, 0), SIGABRT);
+
+        ASSERT_OK(cpu_set_add_range(&c, 0, 0));
+        ASSERT_OK(cpu_set_add_range(&c, 0, 8191));
+}
+
 DEFINE_TEST_MAIN(LOG_DEBUG);