Address gh-47, accept "* * * * Mon%2+2"

let's not error on that

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ## fugit 1.4.5 not yet released
 
+* Accept "* * * Mon%2+2", gh-47
+
 
 ## fugit 1.4.4 released 2021-03-25
 

CREDITS.md

@@ -11,7 +11,7 @@
 * Danny Ben Shitrit https://github.com/DannyBen nat variants, gh-38
 * Dominik Sander https://github.com/dsander #rough_frequency 0, gh-36
 * Milovan Zogovic https://github.com/assembler Cron#match? vs TZ, gh-31
-* Jessica Stokes https://github.com/ticky 0-24 issue with cron, gh-30
+* Jessica Stokes https://github.com/ticky 0-24 issue with cron, gh-30 and gh-47
 * Shai Coleman https://github.com/shaicoleman parse_nat enhancements, gh-24, gh-25, gh-28, and gh-37
 * Jan Stevens https://github.com/JanStevens Fugit.parse('every 15 minutes') gh-22
 * Fabio Pitino https://github.com/hspazio nil on February 30 gh-21

README.md

@@ -215,6 +215,10 @@ c.match?('2019-01-08')  # => false, since (rweek + 1) % 2 == 1
 # ...
 ```
 
+`sun%2` matches if Sunday and `current_date.rweek % 2 == 0`
+`tue%3+2` matches if Tuesday and `current_date.rweek + 2 % 3 == 0`
+`tue%x+y` matches if Tuesday and `current_date.rweek + y % x == 0`
+
 
 ## `Fugit::Duration`
 

lib/fugit/cron.rb

@@ -150,7 +150,7 @@ def weekday_hash_match?(nt, hsh)
 
     def weekday_modulo_match?(nt, mod)
 
-      nt.rweek % mod[0] == mod[1]
+      (nt.rweek + mod[1]) % mod[0] == 0
     end
 
     def weekday_match?(nt)

spec/cron_spec.rb

@@ -551,6 +551,17 @@ class Fugit::Cron::TimeCursor
           expect(nt.utc.to_s).to match(/ 16:00:00 /)
         end
       end
+
+      it 'does not break on "* * * * 1%2+2" (gh-47)' do
+
+        cron0 = Fugit.parse('0 8 * * 1%2+2')
+        cron1 = Fugit.parse('0 8 * * 1%2')
+
+        expect(cron0.next_time('2021-04-21 07:00:00').to_s
+          ).to match(/^2021-05-03 08:00:00 /)
+        expect(cron0.next_time('2021-04-21 07:00:00').to_s
+          ).to eq(cron1.next_time('2021-04-21 07:00:00').to_s)
+      end
     end
   end