Checklist

• Parsing: What is the time zone of the input?
• Parsing: Use Time.zone.parse to parse user input, but first set Time.zone to the user’s time zone.
• UI: What is the user’s time zone?
• UI: Show the time in the user’s time zone: https://github.com/github/time-elements
• Ruby: Time.now uses the operating system’s time zone
• Ruby: Date.today uses the operating system’s time zone
• Ruby: Time.parse uses the operating system’s time zone
• Ruby: Use Range.cover? with time ranges and know how it differs from Range.include?
• Rails: Time.zone.now and Time.current uses Rails’ time zone (config.time_zone in config/application.rb)
• Rails: Time.zone.today uses Rails’ time zone
• Rails: Time.zone.parse uses Rails’ time zone
• Database: Store time in UTC (without time zone information)
• Database: “BETWEEN a AND b” is inclusive
• Database: PostgreSQL’s current_timestamp uses the database time zone (timezone in postgresql.conf)
• API: Use ISO 8601 format
• Daylight savings
• Leap year
• Falsehoods