test(p19): add tests

	- test iterative, map, module, rec and tailrec
	- test data module

p19/lib/date.ml

@@ -1,5 +1,10 @@
 let is_leap year = (year mod 4 = 0 && year mod 100 <> 0) || year mod 400 = 0
 
+let%test "is_leap for leap year 2000" = is_leap 2000 = true
+let%test "is_leap for leap year 2020" = is_leap 2020 = true
+let%test "is_leap for non-leap year 1900" = is_leap 1900 = false
+let%test "is_leap for non-leap year 2023" = is_leap 2023 = false
+
 let days_in_month year month =
   match month with
   | 1 | 3 | 5 | 7 | 8 | 10 | 12 -> 31
@@ -8,10 +13,20 @@ let days_in_month year month =
   | _ -> failwith "Invalid month"
 ;;
 
+let%test "days_in_month for February in leap year" = days_in_month 2020 2 = 29
+let%test "days_in_month for February in non-leap year" = days_in_month 2021 2 = 28
+let%test "days_in_month for January" = days_in_month 2021 1 = 31
+let%test "days_in_month for April" = days_in_month 2021 4 = 30
+
 let zellers_congruence year month day =
   let year, month = if month < 3 then year - 1, month + 12 else year, month in
   let k = year mod 100 in
   let j = year / 100 in
   let f = day + (13 * (month + 1) / 5) + k + (k / 4) + (j / 4) - (2 * j) in
   ((f mod 7) + 7) mod 7
 ;;
+
+let%test "zellers_congruence for 1 Jan 1900 (Monday)" = zellers_congruence 1900 1 1 = 2
+let%test "zellers_congruence for 1 Jan 2000 (Saturday)" = zellers_congruence 2000 1 1 = 0
+let%test "zellers_congruence for 1 Mar 2021 (Monday)" = zellers_congruence 2021 2 28 = 1
+let%test "zellers_congruence for 31 Dec 1999 (Friday)" = zellers_congruence 1999 12 31 = 6

p19/lib/dune

@@ -1,3 +1,7 @@
 (library
  (name p19_lib)
- (modules date tailrec rec map iterative module))
+ (modules date tailrec rec map iterative module)
+ (inline_tests
+  (flags (-verbose)))
+ (preprocess
+  (pps ppx_inline_test)))

p19/lib/iterative.ml

@@ -9,3 +9,5 @@ let count_sundays start_year end_year =
   done;
   !count
 ;;
+
+let%test _ = count_sundays 1901 2000 = 171

p19/lib/map.ml

@@ -9,3 +9,5 @@ let count_sundays start_year end_year =
   in
   List.fold_left (fun acc year -> acc + aux year) 0 years
 ;;
+
+let%test _ = count_sundays 1901 2000 = 171

p19/lib/module.ml

@@ -8,3 +8,5 @@ let count_sundays start_year end_year =
   in
   List.fold_left (fun acc year -> acc + aux year) 0 years
 ;;
+
+let%test _ = count_sundays 1901 2000 = 171

p19/lib/rec.ml

@@ -11,3 +11,5 @@ let rec count_sundays year month day_of_week =
     then new_count + count_sundays (year + 1) 1 next_day_of_week
     else new_count + count_sundays year (month + 1) next_day_of_week)
 ;;
+
+let%test _ = count_sundays 1901 1 2 = 171

p19/lib/tailrec.ml

@@ -11,3 +11,5 @@ let rec count_sundays year month day_of_week count =
     then count_sundays (year + 1) 1 next_day_of_week new_count
     else count_sundays year (month + 1) next_day_of_week new_count)
 ;;
+
+let%test _ = count_sundays 1901 1 2 0 = 171