XCTest Doesn't have ActivitySummaries in TestSummaries

I'm New to Running XCTest. After running : open ~/Library/Developer/Xcode/DerivedData/My_Proj/Logs/Tests/TestSummaries.plist

Question 1 : When open TestSummaries.plist i can find my all Tests.can't find ActivitySummaries for the tests whose TestStatus is Success. But for the tests whose TestStatus is Failure have ActivitySummaries. Why this behavior ?

Question 2 : -For XCUITests ActivitySummaries is present for all Success and Failure tests . But Not for Pure XCTest (Unit)... Can someone Guide me why XCTest doesn't have ActivitySummaries wherein XCUITests does have the same or Is there a way to enable or add it ?