Closures, ViewController & Performance Testing with XCTestCase

Hello. I will with to do performance testing on my swift code for an internship.
I have never done that, before, so my problem could be related to principle of performance testing.
I think I understand the principale of "self.measure" blocks and why it is necessary to execute
the code several hundreds of times.
My first problem is at the beginning, I tempt to do my tests, without pass to "setUp" and "tearDown" functions,
but searching on the Web, I have found it is better to use them, donc I change several things :

<code>

import XCTest
@testable import DernierTest

class PerformanceTests: XCTestCase {

  let viewController = ViewController()
  let secondViewController = SecondViewController()
  let thirdViewController = ThirdViewController()
  let fourthViewController = FourthViewController()

       override func setUp() {
    
             super.setUp()
    
       }

       override func tearDown() {
   
              super.tearDown()
      }

func test_displayFamiliesTask() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
        
            _ = self.viewController.displayFamiliesTask { (success, response, error) in
                
                if error != nil {
                    
                    print(error)
                    return
                    
                }
                if success {
                    
                    guard let datas = response as? [AnyObject] else { return }
                    self?.viewController.displayFamilies(datas: datas)
                    
                }
                
            }
            
        }
        
    }
    
}

func test_displayCategoriesTask() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self.viewController.displayCategoriesTask { (success, response, error) in
                
                if success {
                    
                    guard let datas = response as? [Category] else { return }
                    DispatchQueue.main.async {
                        
                        self?.secondViewController.collectionView.reloadData()
                        
                    }
                    
                }
                    
                else if let error = error {
                    
                    print(error)
                    
                }
            }
            
        }
        
    }
    
}

func test_getAPITokenTask() {
    
    self.measure { [weak self] in
        
        for _ in 0…1000 {
            
            _ = self.thirdViewController.getAPITokenTask()
            
        }
        
    }
    
}

func test_getTagsProductTask() {
    
    self.measure { [weak self] in
        
        for _ in 0...000 {
            
            _ = self.thirdViewController.getTagsProductTask()
            
        }
        
    }
    
}

func test_searchTags() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self.thirdViewController.searchByTag(token: )
            
        }
        
    }
    
}

func test_getFormattedTimestamp() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self.thirdViewController.getFormatedTimestamp()
            
        }
        
    }
    
}

func test_fillFamilies() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            guard let filePath = Bundle.main.path(forResource: "families”, ofType: “json”),
            let fileSource = try? String(contentsOfFile: filePath) else { return }
            _ = self?.viewController.fillFamilies(json: fileSource as? AnyObject)
            
        }
        
    }
    
}

func test_parseJSON() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            guard let filePath = Bundle.main.path(forResource: "results”, ofType: “json”),
                let fileSource = try? String(contentsOfFile: filePath) else { return }
            
            _ = self.thirdViewController.parseJSON(json: fileSource as? AnyObject)
            
        }
        
    }
    
}

func test_fillTags() {
    
    self.measure { [weak self] in
        
        for _ in 0…1000 {
            
            guard let filePath = Bundle.main.path(forResource: “families”, ofType: “json”),
                let fileSource = try? String(contentsOfFile: filePath) else { return }
            
            _ = self.thirdViewController.fillTags(json: fileSource as? AnyObject)
            
        }
        
    }

}

func test_FirstControllerCollectionViewNumberOfItemsInSection() {

    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self.viewController.collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int)
            
        }
        
    }

}

func test_FirstControllerCollectionViewCellForItemAt() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self.viewController.collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath)
            
        }
        
    }
    
}

func test_FirstControllerCollectionViewDidSelectItemAt() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self.viewController.collectionView(_, collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath)
            
        }
        
    }
    
}

func test_SecondControllerCollectionViewNumberOfItemsInSection() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self.secondViewController.collectionView(_, collectionView: UICollectionView, numberOfItemsInSection section: Int)
            
        }
        
    }
}

func test_SecondControllerCollectionViewCellForItemAt() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self.secondViewController.collectionView(_, collectionView: UICollectionView, cellForItemAt indexPath: IndexPath)
            
        }
        
    }

}

func test_SecondControllerCollectionViewDidSelectItemAt() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self.secondViewController.collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath)
            
        }
        
    }
    
}

func test_ThirdControllerCollectionViewNumberOfItemsInSection() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self.thirdViewController.collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int)
            
        }
        
    }
    
}

func test_ThirdControllerCollectionViewCellForItemAt() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self.thirdViewController.collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath)
            
        }
        
    }
    
}

func test_ThirdControllerCollectionViewDidSelectItemAt() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self.thirdViewController.collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath)
            
        }
        
    }

}

}

Other problems are arrived, but until here, compiler did not return warning at least.

After that, I found it is better to use setUp and tearDown and I change my code like that :

import XCTest
@testable import DernierTest

class PerformanceTests: XCTestCase {

var viewController: UIViewController!
var secondViewController: UIViewController!
var thirdViewController: UIViewController!
var fourthViewController: UIViewController!

override func setUp() {
    
    super.setUp()
    
    viewController = ViewController()
    secondViewController = SecondViewController()
    thirdViewController = ThirdViewController()
    fourthViewController = FourthViewController()
    
}

override func tearDown() {
    
    viewController = nil
    secondViewController = nil
    thirdViewController = nil
    fourthViewController = nil
    
    super.tearDown()
    
}

func test_displayFamiliesTask() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
        
            _ = self?.viewController.displayFamiliesTask { (success, response, error) in
                
                if error != nil {
                    
                    print(error)
                    return
                    
                }
                if success {
                    
                    guard let datas = response as? [AnyObject] else { return }
                    self?.viewController.displayFamilies(datas: datas)
                    
                }
                
            }
            
        }
        
    }
    
}

func test_displayCategoriesTask() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self?.viewController.displayCategoriesTask { (success, response, error) in
                
                if success {
                    
                    guard let datas = response as? [Category] else { return }
                    DispatchQueue.main.async {
                        
                        self?.secondViewController.collectionView.reloadData()
                        
                    }
                    
                }
                    
                else if let error = error {
                    
                    print(error)
                    
                }
            }
            
        }
        
    }
    
}

func test_getAPITokenTask() {
    
    self.measure { [weak self] in
        
        for _ in 0…1000 {
            
            _ = self?.thirdViewController.getAPITokenTask()
            
        }
        
    }
    
}

func test_getTagsProductTask() {
    
    self.measure { [weak self] in
        
        for _ in 0...000 {
            
            _ = self?.thirdViewController.getTagsProductTask()
            
        }
        
    }
    
}

func test_searchTags() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self?.thirdViewController.searchByTag(token: )
            
        }
        
    }
    
}

func test_getFormattedTimestamp() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self?.thirdViewController.getFormatedTimestamp()
            
        }
        
    }
    
}

func test_fillFamilies() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            guard let filePath = Bundle.main.path(forResource: "families”, ofType: “json”),
            let fileSource = try? String(contentsOfFile: filePath) else { return }
            _ = self?.viewController.fillFamilies(json: fileSource as? AnyObject)
            
        }
        
    }
    
}

func test_parseJSON() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            guard let filePath = Bundle.main.path(forResource: "results”, ofType: “json”),
                let fileSource = try? String(contentsOfFile: filePath) else { return }
            
            _ = self?.thirdViewController.parseJSON(json: fileSource as? AnyObject)
            
        }
        
    }
    
}

func test_fillTags() {
    
    self.measure { [weak self] in
        
        for _ in 0…1000 {
            
            guard let filePath = Bundle.main.path(forResource: “families”, ofType: “json”),
                let fileSource = try? String(contentsOfFile: filePath) else { return }
            
            _ = self?.thirdViewController.fillTags(json: fileSource as? AnyObject)
            
        }
        
    }

}

func test_FirstControllerCollectionViewNumberOfItemsInSection() {

    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self?.viewController.collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int)
            
        }
        
    }

}

func test_FirstControllerCollectionViewCellForItemAt() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self?.viewController.collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath)
            
        }
        
    }
    
}

func test_FirstControllerCollectionViewDidSelectItemAt() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self?.viewController.collectionView(_, collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath)
            
        }
        
    }
    
}

func test_SecondControllerCollectionViewNumberOfItemsInSection() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self?.secondViewController.collectionView(_, collectionView: UICollectionView, numberOfItemsInSection section: Int)
            
        }
        
    }
}

func test_SecondControllerCollectionViewCellForItemAt() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self?.secondViewController.collectionView(_, collectionView: UICollectionView, cellForItemAt indexPath: IndexPath)
            
        }
        
    }

}

func test_SecondControllerCollectionViewDidSelectItemAt() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self?.secondViewController.collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath)
            
        }
        
    }
    
}

func test_ThirdControllerCollectionViewNumberOfItemsInSection() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self?.thirdViewController.collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int)
            
        }
        
    }
    
}

func test_ThirdControllerCollectionViewCellForItemAt() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self?.thirdViewController.collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath)
            
        }
        
    }
    
}

func test_ThirdControllerCollectionViewDidSelectItemAt() {
    
    self.measure { [weak self] in
        
        for _ in 0...1000 {
            
            _ = self?.thirdViewController.collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath)
            
        }
        
    }

}

}

The compiler send back me warnings for every functions, saying it doesn't find the function in my ViewController, like that :

"Value of type 'UIViewController' has no member 'displayFamiliesTask'"

My first question is where can come these messages, have I need to use "setUp" and "tearDown",
or is it better to do without.
My second question concerns the closures. Is it possible to do a test on a closure, particularly an escaping closure, simply like that, or have I need to use a particular way.

I precise, giving you definition of my functions :

In the first ViewController :

func displayFamiliesTask(completion: @escaping (Bool, Any?, Error?) -> Void) func fillFamilies(json: AnyObject) func displayFamilies(datas: [AnyObject])

In the second ViewController :

func displayCategoriesTask(completion: @escaping (Bool, Any?, Error?) -> Void)

In the third ViewController :

func getTagsProductTask() func getAPITokenTask() func getFormatedTimestamp() -> String func searchByTag(token: String) func parseJSON(json: AnyObject) func fillTags(json: AnyObject)

sorry in advance, if it is not the good category for the topic.