Sample

Choose between Carbon and CarbonImmutable, and get timezone conversion, DST arithmetic and a frozen test clock right

sha256:db94b10dc83113f829139d9b6b88de71e978906568855aa20a460ba480bc0062

Case

Goal

Choose between Carbon and CarbonImmutable, and get timezone conversion, DST arithmetic and a frozen test clock right HOW

Packages

nesbot/carbon 3.13.2

Environment

php 8

Created

2026-08-14T12:55:47Z

Contract

• assert addDay on a Carbon rewrites the receiver and every other reference to it and returns that same object, while addDay on a CarbonImmutable leaves the receiver alone and only the returned value moves
• assert a bare addDay statement whose result is discarded is a write on Carbon and a silent no-op on CarbonImmutable
• assert Carbon extends DateTime and CarbonImmutable extends DateTimeImmutable and neither is an instance of the other, so only DateTimeInterface or CarbonInterface accepts both
• assert a Carbon and a CarbonImmutable holding the same instant compare equal with == and equalTo even across timezones, so comparison cannot detect the mixup
• assert copy clones on both classes while avoidMutation clones a Carbon and returns the same instance for a CarbonImmutable
• assert one slot-building loop returns three distinct dates on CarbonImmutable and three references to one date three days later on Carbon, and that it also advances the caller's start date
• assert the same loop written with avoidMutation returns the identical three dates for both classes and leaves the caller's start date alone
• assert setTimezone keeps the instant and changes the wall clock while shiftTimezone keeps the wall clock and moves the instant back by the offset, so the two answers print differently in Paris and have different UTC timestamps
• assert setTimezone and shiftTimezone both rewrite a Carbon argument in place and return that same object, so the shifting helper moves the caller's instant two hours while its wall clock still prints unchanged
• assert diffInDays reports 2.0 calendar days across both Paris DST boundaries while its third utc argument reports 47/24 and 49/24 elapsed days
• assert diffInDays applies that utc conversion on its own when the two dates name different zones, so reading either side in UTC returns the elapsed answer unasked
• assert diffInHours always reports elapsed hours, 47 and 49 across those same two spans, and has no utc parameter at all, so a third argument passed to it is discarded in silence
• assert the Carbon 3 diffs are signed floats, so reversing the arguments gives -2.0 days and -47.0 hours unless absolute is requested
• assert addDay across the spring-forward day moves 23 real hours while addHours(24) moves 86400 seconds and lands an hour later, and that startOfDay to endOfDay spans 23 hours less a microsecond on that day and 25 on the autumn one
• assert Carbon::parse reads a slash-separated numeric date as American m/d/y and a dash or dot separated one as European d-m-y, and throws InvalidFormatException only when the American reading is impossible
• assert parsing the repeated wall clock hour of the autumn transition yields the standard-time reading with isDST false, one hour later than the same wall clock reached by adding an hour, and that the nonexistent spring hour rolls forward instead of failing
• assert startOfDay uses the instance timezone, so midnight in Paris is the previous calendar day in UTC and converting to UTC before taking the boundary gives an instant one offset hour later
• assert Carbon::setTestNow freezes now, the constructor, parse('now') and CarbonImmutable::now to the identical microsecond for both classes through one shared switch
• assert the frozen clock is rendered in the ambient default timezone rather than the timezone of the value that was set, that relative strings resolve against it while PHP's own time() does not, and that setTestNowAndTimezone moves and restores the default timezone
• assert setTestNow with no argument clears the frozen clock for both classes, and that withTestNow restores the previous state even when its callback throws

Files

• composer.json
• composer.lock
• csx.json
• phpunit.xml
• src/Schedule.php
• test/ScheduleTest.php

Origin Seeder

anonymous

Verification receipts

• php 8 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · composer@1 · 2026-08-14 · ed25519:a2ec939a4c60e243
• · CONTAINER_RUN · compile:SKIPPED · contract:SKIPPED · load:SKIPPED · resolve:FAIL · composer@1 · 2026-08-14 · ed25519:7da3f610facce8bf