Test descriptions of all possible permutations of a cron string

[TheCodedSelf]

e.g. ensure tests are written for:

• 1 * * * *
• • 1 * * *
• • • 1 * *
• • • • 1 *
• • • • • 1

• ---

Et cetera

[TheCodedSelf]

Meaning, all combinations of which fields are left blank, and which contain a number