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iOS test project

Parallelizing iOS tests on virtualized OSX

This is a proof of concept script to divide a time consuming iOS test suite on multiple virtual machines. A quick (~2/3minutes) suite will not benefit from this strategy.

How this works?

Xcode8 has a xcodebuild option called --only-test that allows to run parts of a build so we search the Xcode project test file list and split them across virtual machines--legally--running OSX.

We don't allow to distribute test functions across virtual machines.

Installation steps:

From now on we will refer to your workstation (or CI server) as the HOST.

On the HOST:

  • git clone

  • cd parallelize-tests and then run bundle

  • install OSX server from the AppStore

  • install VmWare Fusion

  • create a new VmWare Fusion OSX virtual machine--follow the wizard that will create the OS from the HOST recovery disk

  • turn on the virtual machine (refered to as GUEST from now on) and set its name ie. (parallel-ios-tests-1)

  • enable the GUEST ssh access from System Preferences -> Sharing

    Provisioning GUEST

    • install xcode and necessary simulators
    • enable xcode developer mode
    • install git
    • install SSH certificate to allow git checkout
    • create a PROJECT_DIRECTORY and git clone your project--the project directory will be needed when Running the tests from the HOST

    Cloning GUEST to create a suite virtual machines

    • turn off the GUEST
    • from VmWare's menu: Virtual Machine -> Create full clone
    • once the new GUEST is turned on change its name
    • repeat this as long as you see your total test time decrease


Currently all the variables have to be provided via ENV variables ie.

LIST_OF_VMS="parallel-ios-testbox-1.local parallel-ios-testbox-2.local parallel-ios-testbox-3.local" PROJECT_FILE=UnitTest.xcodeproj SCHEME=UnitTest VM_PROJECT_DIRECTORY="workspace/parallelize-tests" DESTINATION="platform=iOS Simulator,name=iPhone 7" ruby run.rb

You should see green dots as test succeed and red F when they fail ie.

>> Detected 20 test files.
>> Parallelizing tests on 3 virtual machines
.................F..>> Failing tests:
  -[ExpectedToFailTests testFalse()]
  -[ExpectedToFailTests testTrue()]


Each run will create a new timestamped file in the script's directory ie. ios-parallel-tests-20161010_1026.log. The log contains the whole xcodebuild outputs.


ssh connection to the VmWare virtualmachines via their domain name takes 5/6 seconds--that's because it's attempting to connect to their IPV6 address. To avoid that we added: AddressFamily inet inside ~/.ssh/config.

We saw occasional test fails related to xcodebuild telling us the simulator "is installing or uninstalling, and cannot be launched". When we catch that you will see a orange R on the screen and we retry that test.


Worked at during Pivotal Labs research time by Enrico Teotti (@agenteo) and Tim Kersey (@tkersey)