Would prefer we let `testableBuildSettings` be _just_ the settings that we get from xcodebuild.  Instead of saving this value here, you can access it via the `testableExectutionInfo` object.  e.g. `testableExecutionInfo.testable.target`.

It looks like you need this value inside of `commonOCUnitEventInfoFromBuildSettings:garbageCollectionEnabled:`.  But, if you refactored that method to be...

```
+ (NSDictionary *)commonOCUnitEventInfoFromTestableExecutionInfo:(TestableExecutionInfo *)testableExecutionInfo
                                garbageCollectionEnabled:(NSNumber *)garbageCollectionEnabled
```

... and added the relevant plumbing, you'd have what you need.