todos/UnitTests/Tests/View Models/TaskListViewModelTests.swift

import Foundation
import SwiftData
import SwiftUI
import Testing

@testable import Todos

@Suite("TaskList view model tests")
struct TaskListViewModelTests {

    // MARK: Initializers tests

    @Test(
        "properties are set correctly during initialization",
        arguments: TodoGroup.allCases
    )
    func initialization(for group: TodoGroup) {
        // GIVEN
        // WHEN
        let viewModel = TaskListView.ViewModel(group: group)

        // THEN
        #expect(viewModel.group == group)
        #expect(viewModel.showCompleted == false)
    }

    // MARK: Computed property tests

    @Test(
        "buttonCompleted returns correct values when showCompleted is true",
        arguments: TodoGroup.allCases, [true, false]
    )
    func buttonCompleted(
        for group: TodoGroup,
        showCompleted: Bool
    ) {
        // GIVEN
        let viewModel = TaskListView.ViewModel(group: group)
        
        viewModel.showCompleted = showCompleted

        // WHEN
        let (title, icon) = viewModel.buttonCompleted

        // THEN
        if showCompleted {
            #expect(title == "view.task-list.label.hide-completed")
            #expect(icon == "eye.slash")
        } else {
            #expect(title == "view.task-list.label.show-completed")
            #expect(icon == "eye")
        }
    }

    @Test(
        "canShowCompleted returns correct value for each group",
        arguments: zip(
            TodoGroup.allCases,
            [true, true, true, false]
        )
    )
    func canShowCompleted(
        for group: TodoGroup,
        expects expectation: Bool
    ) {
        // GIVEN
        let viewModel = TaskListView.ViewModel(group: group)

        // WHEN
        let canShowCompleted = viewModel.canShowCompleted

        // THEN
        #expect(canShowCompleted == expectation)
    }

    @Test(
        "navigationTitle returns correct view title for each group",
        arguments: TodoGroup.allCases
    )
    func navigationTitle(for group: TodoGroup) {
        // GIVEN
        let viewModel = TaskListView.ViewModel(group: group)

        // WHEN
        let title = viewModel.navigationTitle

        // THEN
        #expect(title == group.title)
    }

    // MARK: Method tests

    @Test("toggleCompletedVisbility toggles the showCompleted property")
    func toggleCompletedVisibility() {
        // GIVEN
        let viewModel = TaskListView.ViewModel(group: .today)
        let initialValue = viewModel.showCompleted

        // WHEN
        viewModel.toggleCompletedVisibility()
        let afterFirstToggle = viewModel.showCompleted

        viewModel.toggleCompletedVisibility()
        let afterSecondToggle = viewModel.showCompleted

        // THEN
        #expect(initialValue == false)
        #expect(afterFirstToggle == true)
        #expect(afterSecondToggle == false)
    }

}