test: add '1W,3W' interval test

Aren't failing as W-checks were redone, inserting days dynamically into calendar instead of looking up the next fitting day for each flag

Author: Kniggebrot

ccronexpr_test.c

@@ -514,13 +514,19 @@ void test_expr() {
     assert(check_next("0 0 12 1W,2W * ?","2025-01-01_11:00:00", "2025-01-01_12:00:00"));
     assert(check_next("0 0 12 1W,2W * ?","2025-01-01_13:01:00", "2025-01-02_12:00:00"));
     assert(check_next("0 0 12 1W,2W * ?","2025-01-02_12:01:00", "2025-02-03_12:00:00"));
+    assert(check_next("0 0 12 1W,3W * ?","2025-01-01_11:00:00", "2025-01-01_12:00:00"));
+    assert(check_next("0 0 12 1W,3W * ?","2025-01-01_13:01:00", "2025-01-03_12:00:00"));
+    assert(check_next("0 0 12 1W,3W * ?","2025-01-03_12:01:00", "2025-02-03_12:00:00"));
     assert(check_next("0 0 12 1W,15W * ?","2025-01-01_11:00:00", "2025-01-01_12:00:00"));
     assert(check_next("0 0 12 1W,15W * ?","2025-01-01_13:01:00", "2025-01-15_12:00:00"));
     assert(check_next("0 0 12 1W,15W * ?","2025-01-15_12:01:00", "2025-02-03_12:00:00"));
-    // Repeat for 1st May, also a wednesday
+    // Repeat for 1st May, a thursday
     assert(check_next("0 0 12 1W,2W * ?","2025-05-01_11:00:00", "2025-05-01_12:00:00"));
     assert(check_next("0 0 12 1W,2W * ?","2025-05-01_13:01:00", "2025-05-02_12:00:00"));
     assert(check_next("0 0 12 1W,2W * ?","2025-05-02_12:01:00", "2025-06-02_12:00:00"));
+    assert(check_next("0 0 12 1W,3W * ?","2025-05-01_11:00:00", "2025-05-01_12:00:00"));
+    assert(check_next("0 0 12 1W,3W * ?","2025-05-01_13:01:00", "2025-05-02_12:00:00"));
+    assert(check_next("0 0 12 1W,3W * ?","2025-05-02_12:01:00", "2025-06-02_12:00:00"));
     assert(check_next("0 0 12 1W,15W * ?","2025-05-01_11:00:00", "2025-05-01_12:00:00"));
     assert(check_next("0 0 12 1W,15W * ?","2025-05-01_13:01:00", "2025-05-15_12:00:00"));
     assert(check_next("0 0 12 1W,15W * ?","2025-05-15_12:01:00", "2025-06-02_12:00:00"));