Cron Expression Parser | Dataford Interview Questions

Implement a cron expression parser (take-home), runnable from the command line with unit tests

Asked in the Take-home stage. Expected production grade: tests, abstraction, modularity.

Implement parse_cron(expression), which accepts exactly five space-separated fields: minute, hour, day of month, month, and weekday. Return a dictionary mapping each field name to sorted allowed integer values. Support *, comma-separated values, inclusive ranges, and step expressions such as */15 or 1-10/2. Reject malformed expressions and values outside each field's bounds.

Constraints

The expression contains exactly five whitespace-separated fields.
Minute values are between 0 and 59.
Hour values are between 0 and 23.
Day-of-month values are between 1 and 31.
Month values are between 1 and 12.
Weekday values are between 0 and 6.
Supported syntax is wildcard, integer, ascending range, comma-separated list, and an optional positive step.

Function Signature

def parse_cron(expression):

Your question is Cron Expression Parser. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Implement a cron expression parser (take-home), runnable from the command line with unit tests

Asked in the Take-home stage. Expected production grade: tests, abstraction, modularity.

Constraints

The expression contains exactly five whitespace-separated fields.
Minute values are between 0 and 59.
Hour values are between 0 and 23.
Day-of-month values are between 1 and 31.
Month values are between 1 and 12.
Weekday values are between 0 and 6.
Supported syntax is wildcard, integer, ascending range, comma-separated list, and an optional positive step.

Function Signature

def parse_cron(expression):

Your question is Cron Expression Parser. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.