ios-timecop

DESCRIPTION

A library providing "time travel" and "time freezing" capabilities, making it dead simple to test time-dependent code. It inspired by ruby timecop gem.

INSTALL

Install Timecop to your project with CocoaPods by adding the following to your Podfile:

pod 'Timecop'

FEATURES

• Freeze time to a specific point.
• Travel back/forward to a specific point in time, but allow time to continue moving forward from there.
• Scale time by a given scaling factor that will cause time to move at an accelerated pace.

USAGE

Run a time-sensitive test

Person *joe = [Persons findJoe];
[joe purchaseHome];
XCTAssertFalse( [joe MortgageDue] );
// move ahead a month and assert that the mortgage is due
NSDate *aMonthLater = [NSDate dateWithTimeIntervalSinceNow:60*60*24*30];
[Timecop freezeWithDate:aMonthLater block:^{
    XCTAssertTrue( [joe mortgageDue] );
}];  

The difference between Freeze and Travel

freeze is used to statically mock the concept of now. As your program executes, Time.now will not change unless you make subsequent calls into the Timecop API. travel, on the other hand, computes an offset between what we currently think Time.now is (recall that we support nested traveling) and the time passed in. It uses this offset to simulate the passage of time. To demonstrate, consider the following code snippets:

NSDate *aHourAgo = [NSDate dateWithTimeIntervalSinceNow:60*60*-1];
[Timecop freezeWithDate:aHourAgo];
sleep(10)
if( aHourAgo == [NSDate date] ){
    NSLog(@"TIME NOT PASSED");
}

[Timecop finishTravel]; // "turn off" Timecop
[Timecop travelWithDate:aHourAgo];
sleep(10)
if( aHourAgo != [NSDate date] ){
    NSLog(@"TIME PASSED!");
}

Timecop Scale

Let's say you want to test a "live" integration wherein entire days could pass by in minutes while you're able to simulate "real" activity. For example, one such use case is being able to test reports and invoices that run in 30 day cycles in very little time, while also being able to simulate activity via subsequent calls to your application.

# seconds will now seem like hours
[Timecop scaleWithFactor:3600];
NSLog(@"current date :%@", [NSDate date]);

// sleep 1sec
sleep(1);
// seconds later, hours have past it's gone a hour!
NSLog(@"a hour passed! :%@", [NSDate date]);

Timecop SafeMode

Safe mode forces you to use Timecop with the block syntax since it always puts time back the way it was. If you are running in safe mode and use Timecop without the block exceptions will be raised to tell the user they are not being safe.

// turn on safe mode
[Timecop setSafeMode:YES];

// using method without block
[Timecop freezeWithDate:nil];
// *** Terminating app due to uncaught exception 'Timecop Exception', reason: 'Safe mode is enabled, only calls passing a block are allowed.'