add ValidatorTestCase for CronExpression

[Hanmac]

This adds a TestCase for the String Constraint

Closes #32

[codecov]

Codecov Report

Merging #33 (5794b02) into master (335c3a8) will increase coverage by 11.96%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             master      #33       +/-   ##
=============================================
+ Coverage     63.24%   75.21%   +11.96%     
  Complexity       45       45               
=============================================
  Files             6        6               
  Lines           117      117               
=============================================
+ Hits             74       88       +14     
+ Misses           43       29       -14     

Impacted Files	Coverage Δ
src/Validator/CronExpressionValidator.php	100.00% <0.00%> (+100.00%)	⬆️

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[Hanmac]

the static code errors are invalid i think

• the setParameter function isn't internal as they said
• the return type from the provider i don't get it to return the right type without making other tests fail

[loevgaard]

Thank you for this 🎉

[loevgaard]

This commit fixed them, but introduced a new one :D

d7f1516

[loevgaard]

And then we're green: 95473cc

Thanks for your contribution :)