iOS/Swift Snapshot Test utility for UIView, UITableCell, UICollectionViewCell and SwiftUI

SnapshotContainer.swift

import UIKit

final class SnapshotContainer: UIView {
    let view: UIView

    init(_ view: UIView, width: CGFloat, backgroundColor: UIColor = .white) {
        self.view = view

        super.init(frame: .zero)

        translatesAutoresizingMaskIntoConstraints = false
        view.translatesAutoresizingMaskIntoConstraints = false

        addSubview(view)

        NSLayoutConstraint.activate([
            view.topAnchor.constraint(equalTo: topAnchor),
            view.bottomAnchor.constraint(equalTo: bottomAnchor),
            view.leadingAnchor.constraint(equalTo: leadingAnchor),
            view.trailingAnchor.constraint(equalTo: trailingAnchor),
            view.widthAnchor.constraint(equalToConstant: width)
        ])
        self.backgroundColor = backgroundColor
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

SnapshotTestCase.swift

import FBSnapshotTestCase

class SnapshotTestCase: FBSnapshotTestCase {
    func XCTVerifyCollectionCell(wrapping cell: UICollectionViewCell) {
        let container = SnapshotContainer(cell.contentView, width: 375)
        FBSnapshotVerifyView(container, overallTolerance: 0.02)
    }

    func XCTVerifyCell(wrapping cell: UITableViewCell) {
        let container = SnapshotContainer(cell.contentView, width: 375)
        FBSnapshotVerifyView(container, overallTolerance: 0.02)
    }

    func XCTVerify(wrapping view: UIView) {
        let container = SnapshotContainer(view, width: 375)
        FBSnapshotVerifyView(container, overallTolerance: 0.02)
    }
}

// MARK: - SwiftUI

import SwiftUI

extension SnapshotTestCase {
    func XCTVerifySwiftUI<V: View>(wrapping sut: V) {
        let viewController = UIHostingController(rootView: sut)
        viewController.view.width(350)
        viewController.view.drawHierarchy(in: viewController.view.bounds, afterScreenUpdates: true)
        FBSnapshotVerifyView(viewController.view, overallTolerance: 0.02)
    }
}