---
title: "Code coverage issues for Swift projects"
slug: code-coverage-issues-for-swift-projects
section: tech
date: 2015-11-07T17:59:00.000Z
canonical: https://roland.leth.ro/blog/tech/code-coverage-issues-for-swift-projects
---

I stumbled upon a problem recently (the full story can be found on [Apple Developer Forums](https://forums.developer.apple.com/thread/20283)) and the short version is: running the app or the tests without code coverage enabled always worked fine, but turning it on caused errors to appear, breaking the build process when trying to test.

*Hunting attemp #75*. One of the errors raised was `Segmentation fault 11`, which appeared for several Swift files during the *Compile Swift source files* phase. This is an error I remembered having in the early days of Swift when writing daring short syntax, like:

```swift
// UILabel convenience init
convenience init(text: String, font: UIFont)

// UIFont helper
class func boldFont(ofSize size: CGFloat) -> UIFont {
  return UIFont(name: "AvenirNext-Bold", size: size)!
}

UILabel(
  text: "Test",
  font: .boldFont(ofSize: 15)
)

// This wouldn't compile, with segmentation fault 11,
// and I would have to write the full thing, UIFont.boldFontOfSize(15)
```

So I went in one of the smallest Swift files with issues, added "long" syntax everywhere, and, weirdly enough, it was still not compiling. 

Next, in a desperate attempt, I went ahead and stripped the code of all ternary conditions and optionals (replacing with bangs `!`), and it now worked. Huh? 

Anyway, adding back the old code, bit by bit, revealed the culprit - variables with ternary conditioned default values, like:

```swift
private let leftMargin: CGFloat = isPad ? 32 : 16 // var made no difference
private let leftMargin: CGFloat = CGFloat((1 == 1) ? CGFloat(32) : CGFloat(16)) // desperation moment
```

Changing them to computed properties, or lazy variables did the trick, and now code coverage finally works:

```swift
private var leftMargin: CGFloat {
 return isPad ? 32 : 16
}
private lazy var leftMargin: CGFloat = {
 return isPad ? 32 : 16
}()
```

This whole thing seems so simple, I have the feeling I'm just missing something obvious; please [let me know](https://bsky.app/profile/roland.leth.ro) if so.