extremely slow unit tests in Xcode 7

[c3farrell]

Summary:
Xcode 6.4 ran 3000 specta unit tests in about 40 seconds.
Xcode 7 runs about 500 specta unit tests in about 5 minutes.

Steps to Reproduce:

1. new project
2. write substantial number of unit tests
3. run unit tests

Expected Results:
expect the unit tests to run as fast or faster in Xcode 7 as Xcode 6.4

Actual Results:
unit tests run much slower in Xcode 7 than they did in Xcode 6.4

Version:
Xcode 7, OS X 10.10.5

[rbaumbach]

+1

[michaeltansg]

+1

[rbaumbach]

After much investigation on this issue, it was determined that the culprit is in fact the iOS 9 simulator. If you download the 8.4 version (if you haven't already) and run your specs with it, it will be as fast as it used to be.

I'm not sure what else we can do other than to let Apple know that the iOS 9 simulator is extremely slow.

[orta]

sigh

[fatuhoku]

Sigh indeed. I would love to practise test-driven development but at every turn, it's either compilation, or the speed of loading the tests, the performance of the simulator, that erodes at the benefits of testing.

[StatusReport]

The workaround we currently did is to remove the verify-after-running of class methods (if you mock class methods, you probably want to refactor your code for many reasons anyway), which dramatically speeded up things. See Lightricks/ocmock@6d8f2c5.

[tonyarnold]

There have been a few comments from Apple engineers on Twitter that the slowness in running unit tests is an OS X bug. No word on whether it's fixed in 10.10.2 beta.

[programmerdave]

Any updates on this from Apple dev? Is there a radar ticket open for this?

[aterribili]

+1