TableView isSelected Scenario Swift 的单元测试 [英] Unit Test for TableView isSelected Scenario Swift

问题描述

我有一个简单的场景和 tableView.

I have a simple scenario and tableView.

我需要选择 3 个单元格，即使我滚动它也会保持原样.我可以选择 1、2 或 3 个单元格，但不能选择 4 个或更多.当我选择 4 个单元格时，什么都不会发生.如果有 3 个选定的单元格并且我单击其中一个单元格，则应取消选择我选择的单元格.到现在为止还挺好.感谢@vadian 的帮助，我可以实现如下.但是我一整天都在为这个场景写单元测试，但无法处理它..我决定向社区求助，但仍然找不到方法..

I need to select 3 cells and and even I scroll it will be stay like. I can select 1, 2 or 3 cells but not 4 or more.When I select 4 cells nothing should happen. If there are 3 selected cells and I click one of them the cell which I selected should be deselected. So far so good. Thanks to @vadian help I can make this happen as below. But I tried all day writing unit test for this scenario but could not handle it.. I decided to ask help community and still could not find a way..

问题是:对于这种情况，我如何用一种很好的方法编写单元测试?

Question is: How can I write unit test with a nice approach for this scenario ?

    /// My Model ///

struct Item: Codable {
    
    let name: String
    let image: String
   
    var isSelected = false
   
    enum CodingKeys: String, CodingKey {
        case name = "name"
        case image = "image"
      
    }
}

// MARK: - UITableViewDelegate
extension ViewController: UITableViewDelegate {

let items = [Item]() // fetched from network, there is item objects inside it.

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        
        items[indexPath.row].isSelected.toggle()
        tableView.reloadRows(at: [indexPath], with: .automatic)
        
    }
    
    func tableView(_ tableView: UITableView, willSelectRowAt indexPath: IndexPath) -> IndexPath? {
                
        return items[indexPath.row].isSelected || items.filter{$0.isSelected}.count < 3 ? indexPath : nil

    }
}
// MARK: - UITableViewDataSource
extension ItemViewModel: UITableViewDataSource {

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "Food", for: indexPath) as! FoodTableViewCell
        
        let item = self.items[indexPath.row]

        cell.isSelected = item.isSelected
      
        return cell
    }
  }
}

推荐答案

当然，您可以为 tableView 操作编写许多单元测试，但我同意 Matt 在这应该很简单"的观点.您的 ViewModel 需要根据单独关注"进行处理；原则，否则需要重构.我假设您将所有逻辑移到 ViewModel 中，然后您可以编写如下单元测试.

Of course, you can write many unit tests for tableView actions but I agree with Matt in terms of "this should be simple". Your ViewModel needs to be handled according to "Separate Concern" principles otherwise it needs to be refactored. I assume you move all logic into ViewModel then you can write a unit test as below.

import Foundation

class YourViewControllerTest: XCTestCase {
    
    var viewModel: ItemViewModel!
    fileprivate var fetcher: MockItemFetcher!
    
    var tableView: UITableView!
    
    override func setUp() {
        super.setUp()
        
        fetcher = MockItemFetcher()
        viewModel = ItemViewModel(fetchable: fetcher)
        
    }
    
    override func tearDown() {
        viewModel = nil
        fetcher = nil
        tableView = nil
        super.tearDown()
    }
    
    /// test the one cell can be selectable or not
    func test_did_select_a_cell() {
        
        let items = [Item(name: "", image: "",)]
        // given
        fetcher.items = items
        viewModel.fetchItems()
        
        let viewController = YourViewController()
        let tableView = UITableView()
        viewController.viewModel = viewModel
        
        // when
        viewController.tableView(tableView, didSelectRowAt: IndexPath(row: 0, section: 0))
        let willBeSelected = viewController.tableView(tableView, willSelectRowAt: IndexPath(row: 0, section: 0))
        
        // then
        XCTAssertNotNil(willBeSelected)
        XCTAssertTrue(viewModel.items.value[0].isSelected) // please note that items need to be binded - viewmodel-view
    }

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