Support scheduling task every month on specific date

Author: strika

src/commands/schedule_tasks.janet

@@ -27,6 +27,7 @@
         "every month" (= (date :day) 1)
         "every 3 months" (and (= (date :day) 1)
                               (number? (index-of (date :month) [1 4 7 10])))
+        (string "every month on " (date :day)) true
         (string "every year on " (remove-year formatted-date)) true
         (string "on " formatted-date) true
         "every last day" (date/last-day-of-month? date)

test/commands/schedule_tasks_test.janet

@@ -49,6 +49,14 @@
   (test (not (scheduled-for? task (d/date 2022 1 29))) true)  # Saturday
   (test (not (scheduled-for? task (d/date 2022 1 30))) true)) # Sunday
 
+(deftest "every month on some date"
+  (def task (task/build-scheduled-task 42 "Review logs" "every month on 15"))
+  (test (scheduled-for? task (d/date 2022 1 15)) true)
+  (test (scheduled-for? task (d/date 2022 2 15)) true)
+  (test (scheduled-for? task (d/date 2022 10 15)) true)
+  (test (not (scheduled-for? task (d/date 2022 1 14))) true)
+  (test (not (scheduled-for? task (d/date 2022 1 16))) true))
+
 (deftest "every year on some date"
   (def task (task/build-scheduled-task 42 "Review logs" "every year on 01-27"))
   (test (scheduled-for? task (d/date 2022 1 27)) true)