Group tasks feature (#3)

This PR contains the work done to implement the **Group Task** feature, and to integrate it into the main content view of the app. Furthermore, an issue related to triggering a view update after inserting the todo tasks into the model container has been fixed.

Reviewed-on: rock-n-code/todos-app#3
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

App/Previews/Modifiers/EmptyContainerModifier.swift

@@ -0,0 +1,79 @@
+import SwiftData
+import SwiftUI
+
+/// A preview modifier that provides an empty SwiftData model container for SwiftUI previews.
+///
+/// This modifier creates an in-memory SwiftData model container with no data, useful for testing and previewing views in their empty or initial state.
+/// It's particularly helpful for testing empty state UI, loading states, or views that should gracefully handle no data.
+///
+/// ## Usage
+/// Use the `.emptyContainer` trait on your preview:
+///
+/// ```swift
+/// #Preview(traits: .emptyContainer) {
+///     TaskGroupListView()
+/// }
+/// ```
+///
+/// This automatically provides an empty model container to the preview, allowing SwiftData queries to return empty results.
+struct EmptyContainerModifier: PreviewModifier {
+    
+    // MARK: Functions
+    
+    /// Creates and configures a shared in-memory model container with no data.
+    ///
+    /// This method is called once when the preview is loaded and creates an in-memory
+    /// SwiftData container with no persisted entities. The container is configured
+    /// to store data only in memory, ensuring previews don't affect any persistent storage.
+    ///
+    /// - Returns: An empty `ModelContainer` configured for in-memory storage.
+    /// - Throws: An error if the model container cannot be created.
+    static func makeSharedContext() async throws -> ModelContainer {
+        try ModelContainer(
+            for: Todo.self,
+            configurations: .init(isStoredInMemoryOnly: true)
+        )
+    }
+    
+    /// Applies the empty model container to the preview content.
+    ///
+    /// This method is called by SwiftUI to apply the modifier to the preview.
+    /// It injects the empty model container into the SwiftUI environment, making it
+    /// available to any views that use `@Query` or `@Environment(\.modelContext)`.
+    /// Queries will return empty results, allowing you to test empty state behavior.
+    ///
+    /// - Parameters:
+    ///   - content: The preview content to modify.
+    ///   - context: The empty model container.
+    /// - Returns: The content with the empty model container applied.
+    func body(
+        content: Content,
+        context: ModelContainer
+    ) -> some View {
+        content.modelContainer(context)
+    }
+    
+}
+
+// MARK: - PreviewTrait
+
+extension PreviewTrait where T == Preview.ViewTraits {
+    
+    /// A preview trait that provides an empty model container.
+    ///
+    /// Use this trait to test views in their empty state without any data.
+    /// This is particularly useful for testing empty state UI, placeholder content,
+    /// and ensuring views handle the absence of data gracefully.
+    ///
+    /// ## Example
+    /// ```swift
+    /// #Preview("Empty State", traits: .emptyContainer) {
+    ///     TaskGroupListView()
+    /// }
+    /// ```
+    ///
+    /// The view will receive an empty SwiftData container, causing any `@Query`
+    /// properties to return empty collections.
+    static var emptyContainer: Self = .modifier(EmptyContainerModifier())
+    
+}

App/Previews/Modifiers/SampleTaskDataModifier.swift

@@ -0,0 +1,131 @@
+import SwiftData
+import SwiftUI
+
+/// A preview modifier that provides sample task data for SwiftUI previews.
+///
+/// This modifier creates an in-memory SwiftData model container populated with representative sample todos across all task groups
+/// (today, upcoming, overdue, completed).
+/// It's designed to be used with SwiftUI previews to display realistic data without
+/// requiring a persistent database.
+///
+/// ## Usage
+/// Use the `.sampleTasks` trait on your preview:
+///
+/// ```swift
+/// #Preview(traits: .sampleTasks) {
+///     TaskGroupListView()
+/// }
+/// ```
+///
+/// This automatically provides a model container with sample data to the preview.
+struct SampleTaskDataModifier: PreviewModifier {
+
+    // MARK: Functions
+
+    /// Creates and configures a shared in-memory model container with sample task data.
+    ///
+    /// This method is called once when the preview is loaded and creates an in-memory
+    /// SwiftData container populated with 8 representative todo tasks spanning all
+    /// task groups and various configurations.
+    ///
+    /// - Returns: A `ModelContainer` configured for in-memory storage with sample data.
+    /// - Throws: An error if the model container cannot be created.
+    static func makeSharedContext() async throws -> ModelContainer {
+        let modelContainer = try ModelContainer(
+            for: Todo.self,
+            configurations: .init(isStoredInMemoryOnly: true)
+        )
+
+        let calendar: Calendar = .current
+        let today: Date = .now
+        let tomorrow: Date = calendar.date(byAdding: .day, value: 1, to: today) ?? today
+        let yesterday = calendar.date(byAdding: .day, value: -1, to: today) ?? today
+
+        let tasks: [Todo] = [
+            .init(
+                title: "Today task 1",
+                due: today
+            ),
+            .init(
+                title: "Today task 2",
+                note: "This is some random note attached to the task.",
+                due: today
+            ),
+            .init(
+                title: "Tomorrow task",
+                due: tomorrow
+            ),
+            .init(
+                title: "Next week task",
+                note: "This is some random note attached to the task.",
+                due: calendar.date(byAdding: .day, value: 7, to: today) ?? today
+            ),
+            .init(
+                title: "Yesterday task",
+                due: yesterday
+            ),
+            .init(
+                title: "Last week task",
+                note: "This is some random note attached to the task.",
+                due: calendar.date(byAdding: .day, value: -7, to: today) ?? today
+            ),
+            .init(
+                title: "Completed task 1",
+                due: today,
+                completed: today
+            ),
+            .init(
+                title: "Completed task 2",
+                note: "This is some random note attached to the task.",
+                due: yesterday,
+                completed: today
+            ),
+        ]
+
+        for task in tasks {
+            modelContainer.mainContext.insert(task)
+        }
+
+        return modelContainer
+    }
+
+    /// Applies the model container to the preview content.
+    ///
+    /// This method is called by SwiftUI to apply the modifier to the preview.
+    /// It injects the model container into the SwiftUI environment, making it
+    /// available to any views that use `@Query` or `@Environment(\.modelContext)`.
+    ///
+    /// - Parameters:
+    ///   - content: The preview content to modify.
+    ///   - context: The model container with sample data.
+    /// - Returns: The content with the model container applied.
+    func body(
+        content: Content,
+        context: ModelContainer
+    ) -> some View {
+        content.modelContainer(context)
+    }
+
+}
+
+// MARK: - PreviewTrait
+
+extension PreviewTrait where T == Preview.ViewTraits {
+
+    /// A preview trait that provides sample task data.
+    ///
+    /// Use this trait to automatically populate previews with realistic sample todos
+    /// without manually creating a model container and inserting data.
+    ///
+    /// ## Example
+    /// ```swift
+    /// #Preview(traits: .sampleTasks) {
+    ///     TaskGroupListView()
+    /// }
+    /// ```
+    ///
+    /// This is equivalent to manually creating a container with sample data but
+    /// much more concise and reusable across multiple previews.
+    static var sampleTasks: Self = .modifier(SampleTaskDataModifier())
+
+}

App/Resources/Localizable.xcstrings

@@ -1,6 +1,50 @@
 {
   "sourceLanguage" : "en",
   "strings" : {
+    "enumeration.todo-group.title.completed" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Completed"
+          }
+        }
+      }
+    },
+    "enumeration.todo-group.title.overdue" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Overdue"
+          }
+        }
+      }
+    },
+    "enumeration.todo-group.title.today" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Today"
+          }
+        }
+      }
+    },
+    "enumeration.todo-group.title.upcoming" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Upcoming"
+          }
+        }
+      }
+    },
     "view.new-task.navigation.title" : {
       "extractionState" : "manual",
       "localizations" : {
@@ -66,6 +110,17 @@
           }
         }
       }
+    },
+    "view.task-group-list.navigation.title" : {
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Todos"
+          }
+        }
+      }
     }
   },
   "version" : "1.1"

App/Sources/Enumerations/TodoGroup.swift

@@ -0,0 +1,70 @@
+import Foundation
+import SwiftUI
+
+/// Categorizes todo tasks into groups based on their due dates and completion status.
+///
+/// This enumeration provides a semantic grouping mechanism for organizing and filtering todo tasks throughout the application.
+/// Each case represents a distinct category that helps users manage their tasks based on temporal relevance and completion state.
+enum TodoGroup {
+    /// Tasks that have been marked as done, regardless of due date.
+    case completed
+    /// Tasks with due dates in the past that remain incomplete.
+    case overdue
+    /// Tasks due on the current day that are not yet completed.
+    case today
+    /// Tasks due in the future that are not yet completed.
+    case upcoming
+}
+
+// MARK: - Computed
+
+extension TodoGroup {
+
+    /// The color associated with the task group.
+    var color: Color {
+        switch self {
+            case .completed: .gray
+            case .overdue: .red
+            case .today: .blue
+            case .upcoming: .green
+        }
+    }
+
+    /// The system icon name for the task group.
+    var iconName: String {
+        switch self {
+            case .completed: "checkmark.circle.fill"
+            case .overdue: "calendar.badge.exclamationmark"
+            case .today: "calendar.badge.clock"
+            case .upcoming: "calendar"
+        }
+    }
+
+    /// The display title for the task group.
+    var title: LocalizedStringKey {
+        switch self {
+            case .completed: "enumeration.todo-group.title.completed"
+            case .overdue: "enumeration.todo-group.title.overdue"
+            case .today: "enumeration.todo-group.title.today"
+            case .upcoming: "enumeration.todo-group.title.upcoming"
+
+        }
+    }
+
+}
+
+// MARK: - CaseIterable
+
+extension TodoGroup: CaseIterable {
+
+    static var allCases: [TodoGroup] { [.today, .upcoming, .overdue, .completed] }
+
+}
+
+// MARK: - Identifiable
+
+extension TodoGroup: Identifiable {
+
+    var id: Self { self }
+
+}

App/Sources/View Models/ContentViewModel.swift

@@ -11,7 +11,7 @@ extension ContentView {
     /// The view model manages:
     /// - Presentation state for the new task view within a sheet.
     @Observable
-    class ViewModel {
+    final class ViewModel {
 
         // MARK: Properties
 

App/Sources/View Models/NewTaskViewModel.swift

@@ -13,7 +13,7 @@ extension NewTaskView {
     /// - Form validation (ensuring title is not empty)
     /// - Saving the todo to SwiftData model context
     @Observable
-    class ViewModel {
+    final class ViewModel {
 
         // MARK: Properties
 

App/Sources/View Models/TaskGroupListViewModel.swift

@@ -0,0 +1,87 @@
+import SwiftData
+import SwiftUI
+
+extension TaskGroupListView {
+
+    /// View model for managing the logic for the task group list view.
+    ///
+    /// This observable class encapsulates the state and business logic for the task group list view.
+    /// It follows the MVVM pattern to separate presentation logic from the view layer.
+    ///
+    /// ## Responsibilities
+    /// - Providing access to all task groups for iteration
+    /// - Efficiently counting tasks per group using SwiftData fetch descriptors
+    /// - Managing date calculations for group categorization
+    @Observable
+    final class ViewModel {
+
+        // MARK: Properties
+
+        /// The calendar used for date calculations.
+        ///
+        /// This calendar is used to determine day boundaries for categorizing tasks into date groups: today, upcoming, overdue.
+        /// Defaults to the current calendar.
+        private let calendar: Calendar
+
+        // MARK: Initialization
+
+        /// Initializes a new view model instance.
+        ///
+        /// - Parameter calendar: The calendar to use for date calculations. Defaults to `.current`.
+        init(calendar: Calendar = .current) {
+            self.calendar = calendar
+        }
+
+        // MARK: Computed
+
+        /// Returns all available task groups in an predetermined order.
+        ///
+        /// This computed property provides access to all task group cases for iteration in the view.
+        ///
+        /// - Returns: An array of all `TodoGroup` cases in a predetermined order.
+        var groups: [TodoGroup] {
+            TodoGroup.allCases
+        }
+
+        // MARK: Functions
+
+        /// Calculates the number of tasks for a given task group from an in-memory collection.
+        ///
+        /// This method filters the provided tasks array to count only those tasks that belong
+        /// to the specified group based on their due date and completion status. Tasks are
+        /// categorized as follows:
+        ///
+        /// - **Completed**: Tasks with a non-nil `completed` date
+        /// - **Overdue**: Incomplete tasks due before today
+        /// - **Today**: Incomplete tasks due today (from start of day to end of day)
+        /// - **Upcoming**: Incomplete tasks due tomorrow or later
+        ///
+        /// - Parameters:
+        ///   - tasks: The array of tasks to filter and count.
+        ///   - group: The task group to count tasks for.
+        /// - Returns: The number of tasks in the specified group.
+        func count(
+            _ tasks: [Todo],
+            for group: TodoGroup
+        ) -> Int {
+            let today = calendar.startOfDay(for: .now)
+            let tomorrow = calendar.date(byAdding: .day, value: 1, to: today) ?? .now
+
+            return tasks
+                .filter { task in
+                    switch group {
+                        case .completed:
+                            task.completed != nil
+                        case .overdue:
+                            task.completed == nil && task.due < today
+                        case .today:
+                            task.completed == nil && task.due >= today && task.due < tomorrow
+                        case .upcoming:
+                            task.completed == nil && task.due >= tomorrow
+                    }
+                }
+                .count
+        }
+
+    }
+}

App/Sources/Views/ContentView.swift

@@ -27,7 +27,7 @@ struct ContentView: View {
     var body: some View {
         NavigationView {
             ZStack(alignment: .bottomTrailing) {
-                List {}
+                TaskGroupListView()
 
                 Button(action: viewModel.showNewTask) {
                     Image(systemName: "plus")

App/Sources/Views/NewTaskView.swift

@@ -52,7 +52,7 @@ struct NewTaskView: View {
                         "view.new-task.placeholder.title",
                         text: $viewModel.title
                     )
-                    .autocapitalization(.none)
+                    .autocapitalization(.sentences)
                     .autocorrectionDisabled(false)
                     .keyboardType(.asciiCapable)
 
@@ -61,7 +61,7 @@ struct NewTaskView: View {
                         text: $viewModel.note,
                         axis: .vertical
                     )
-                    .autocapitalization(.none)
+                    .autocapitalization(.sentences)
                     .autocorrectionDisabled(false)
                     .keyboardType(.asciiCapable)
                     .lineLimit(3 ... 6)
@@ -99,7 +99,9 @@ struct NewTaskView: View {
 
 // MARK: - Previews
 
-#Preview("New todo task") {
+#Preview(
+    "New todo task",
+    traits: .emptyContainer
+) {
     NewTaskView()
-        .modelContainer(for: Todo.self, inMemory: true)
 }

App/Sources/Views/TaskGroupList/TaskGroupListCard.swift

@@ -0,0 +1,113 @@
+import SwiftUI
+
+extension TaskGroupListView {
+    
+    /// A card-style view representing a single todo task group with its count.
+    ///
+    /// This view displays a task group as a compact card showing:
+    /// - The group's icon and title on the left
+    /// - The task count on the right
+    /// - A tinted background using the group's color
+    ///
+    /// The view is designed to be used within the `TaskGroupListView` and is typically
+    /// wrapped in a `NavigationLink` to allow navigation to detailed task lists.
+    struct Card: View {
+
+        // MARK: Properties
+
+        /// The number of tasks.
+        private let count: Int
+        
+        /// The task group.
+        private let group: TodoGroup
+
+        // MARK: Initializers
+
+        /// Creates a task group list card.
+        /// - Parameters:
+        ///   - group: The task group to display.
+        ///   - count: The number of tasks in the group.
+        init(
+            group: TodoGroup,
+            count: Int
+        ) {
+            self.count = count
+            self.group = group
+        }
+
+        // MARK: Body
+
+        /// The content and behavior of the view.
+        ///
+        /// Displays a horizontal card layout with the group icon and title on the left,
+        /// and the task count on the right, all within a colored background.
+        var body: some View {
+            HStack {
+                VStack(
+                    alignment: .leading,
+                    spacing: 8
+                ) {
+                    Image(systemName: group.iconName)
+                        .font(.system(size: 40))
+                        .foregroundStyle(group.color)
+                    
+                    Text(group.title)
+                        .font(.headline)
+                        .foregroundStyle(.primary)
+                        .frame(
+                            maxWidth: .infinity,
+                            alignment: .leading
+                        )
+                }
+                .padding(.vertical, 24)
+                
+                Spacer()
+
+                Text("\(count)")
+                    .font(.title)
+                    .fontWeight(.bold)
+                    .foregroundStyle(group.color)
+            }
+            .padding(.horizontal, 24)
+            .background(
+                RoundedRectangle(cornerRadius: 8)
+                    .fill(group.color.opacity(0.1))
+            )
+        }
+    }
+
+}
+
+// MARK: - Previews
+
+#Preview("Today item") {
+    TaskGroupListView.Card(
+        group: .today,
+        count: .random(in: 0...20)
+    )
+    .padding(.horizontal, 16)
+}
+
+#Preview("Upcoming item") {
+    TaskGroupListView.Card(
+        group: .upcoming,
+        count: .random(in: 0...20)
+    )
+    .padding(.horizontal, 16)
+}
+
+#Preview("Overdue item") {
+    TaskGroupListView.Card(
+        group: .overdue,
+        count: .random(in: 0...20)
+    )
+    .padding(.horizontal, 16)
+}
+
+#Preview("Completed item") {
+    TaskGroupListView.Card(
+        group: .completed,
+        count: .random(in: 0...20)
+    )
+    .padding(.horizontal, 16)
+}

App/Sources/Views/TaskGroupListView.swift

@@ -0,0 +1,77 @@
+import SwiftData
+import SwiftUI
+
+/// A view that displays todo tasks grouped by date and completion categories.
+///
+/// This view serves as the main interface for browsing tasks organized into four groups:
+/// - **Today**: Tasks due today that are not yet completed
+/// - **Upcoming**: Tasks due in the future that are not yet completed
+/// - **Overdue**: Tasks due in the past that are not yet completed
+/// - **Completed**: Tasks that have been marked as done
+struct TaskGroupListView: View {
+
+    // MARK: Properties
+
+    /// Query to monitor all todo tasks for changes.
+    ///
+    /// This query triggers view updates whenever todo tasks are inserted, updated, or deleted,
+    /// ensuring the task counts displayed in the view remain accurate.
+    @Query
+    private var tasks: [Todo]
+
+    /// The view model managing the state and logic for this view.
+    ///
+    /// Handles task counting and provides access to all task groups.
+    /// Initialized with the default calendar for date calculations.
+    @State
+    private var viewModel = ViewModel()
+
+    // MARK: Body
+
+    /// The content and behavior of the view.
+    ///
+    /// Displays a scrollable vertical list of task group cards. Each card shows:
+    /// - The group's icon in its associated color
+    /// - The group's title
+    /// - The current count of tasks in that group
+    ///
+    /// Cards are tappable and navigate to a detailed task list for the selected group.
+    /// Task counts are fetched on-demand from the model context for each render.
+    var body: some View {
+        ScrollView {
+            VStack(spacing: 16) {
+                ForEach(viewModel.groups) { group in
+                    NavigationLink(destination: TaskListView(group: group)) {
+                        Card(
+                            group: group,
+                            count: viewModel.count(tasks, for: group)
+                        )
+                    }
+                    .buttonStyle(.plain)
+                }
+            }
+            .padding(.horizontal)
+        }
+        .navigationTitle("view.task-group-list.navigation.title")
+    }
+}
+
+// MARK: - Previews
+
+#Preview(
+    "Task group list with empty tasks",
+    traits: .emptyContainer
+) {
+    NavigationStack {
+        TaskGroupListView()
+    }
+}
+
+#Preview(
+    "Task group list with sample tasks",
+    traits: .sampleTasks
+) {
+    NavigationStack {
+        TaskGroupListView()
+    }
+}

Todos.xcodeproj/project.pbxproj

@@ -378,6 +378,7 @@
 				ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME = AccentColor;
 				CODE_SIGN_STYLE = Automatic;
 				CURRENT_PROJECT_VERSION = 1;
+				DEVELOPMENT_ASSET_PATHS = "App/Previews/Modifiers/SampleTaskDataModifier.swift App/Previews/Modifiers/EmptyContainerModifier.swift";
 				DEVELOPMENT_TEAM = 7FMNM89WKG;
 				ENABLE_APP_SANDBOX = YES;
 				ENABLE_HARDENED_RUNTIME = YES;
@@ -423,6 +424,7 @@
 				ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME = AccentColor;
 				CODE_SIGN_STYLE = Automatic;
 				CURRENT_PROJECT_VERSION = 1;
+				DEVELOPMENT_ASSET_PATHS = "App/Previews/Modifiers/SampleTaskDataModifier.swift App/Previews/Modifiers/EmptyContainerModifier.swift";
 				DEVELOPMENT_TEAM = 7FMNM89WKG;
 				ENABLE_APP_SANDBOX = YES;
 				ENABLE_HARDENED_RUNTIME = YES;

UnitTests/Tests/Enumerations/TodoGroupTests.swift

@@ -0,0 +1,99 @@
+import Foundation
+import SwiftUI
+import Testing
+
+@testable import Todos
+
+@Suite("TodoGroup enumeration tests")
+struct TodoGroupTests {
+
+    // MARK: Computed tests
+
+    @Test(
+        "group color match expected values",
+        arguments: zip(
+            TodoGroup.allCases,
+            [Color.blue, .green, .red, .gray]
+        )
+    )
+    func color(
+        for group: TodoGroup,
+        expects expectation: Color
+    ) {
+        // GIVEN
+        // WHEN
+        let color = group.color
+
+        // THEN
+        #expect(color == expectation)
+    }
+
+    @Test(
+        "group icon names match expected values",
+        arguments: zip(
+            TodoGroup.allCases,
+            ["calendar.badge.clock", "calendar", "calendar.badge.exclamationmark", "checkmark.circle.fill"]
+        )
+    )
+    func iconName(
+        for group: TodoGroup,
+        expects expectation: String
+    ) {
+        // GIVEN
+        // WHEN
+        let iconName = group.iconName
+
+        // THEN
+        #expect(iconName == expectation)
+    }
+
+    @Test(
+        "group titles match expected values",
+        arguments: zip(
+            TodoGroup.allCases,
+            ["today", "upcoming", "overdue", "completed"]
+        )
+    )
+    func title(
+        for group: TodoGroup,
+        expects expectation: String
+    ) {
+        // GIVEN
+        let key = "enumeration.todo-group.title." + expectation
+
+        // WHEN
+        let title = group.title
+
+        // THEN
+        #expect(title == .init(key))
+    }
+
+    // MARK: Case Iteration Tests
+
+    @Test("all cases contains all cases, in correct order")
+    func allCases() {
+        // GIVEN
+        // WHEN
+        let allCases = TodoGroup.allCases
+
+        // THEN
+        #expect(allCases.count == 4)
+        #expect(allCases[0] == .today)
+        #expect(allCases[1] == .upcoming)
+        #expect(allCases[2] == .overdue)
+        #expect(allCases[3] == .completed)
+    }
+
+    // MARK: Identifiable Tests
+
+    @Test("id returns an identity of a case", arguments: TodoGroup.allCases)
+    func id(for group: TodoGroup) {
+        // GIVEN
+        // WHEN
+        let id = group.id
+
+        // THEN
+        #expect(id == group)
+    }
+
+}

UnitTests/Tests/View Models/ContentViewModelTests.swift

@@ -4,7 +4,7 @@ import Testing
 
 @testable import Todos
 
-@Suite("ContentView.ViewModel Tests")
+@Suite("ContentView view model tests")
 struct ContentViewModelTests {
 
     // MARK: Initialization Tests

UnitTests/Tests/View Models/NewTaskViewModelTests.swift

@@ -4,7 +4,7 @@ import Testing
 
 @testable import Todos
 
-@Suite("NewTaskView ViewModel Tests")
+@Suite("NewTaskView view model tests")
 struct NewTaskViewModelTests {
 
     // MARK: Initialization tests

UnitTests/Tests/View Models/TaskGroupListViewModelTests.swift

@@ -0,0 +1,82 @@
+import Foundation
+import SwiftData
+import Testing
+
+@testable import Todos
+
+@Suite("TaskGroupListView view model tests")
+struct TaskGroupListViewModelTests {
+
+    // MARK: Properties
+
+    private let calendar: Calendar = .current
+
+    // MARK: Computed tests
+
+    @Test("groups returns cases in predetermined order")
+    func groups() {
+        // GIVEN
+        let viewModel = TaskGroupListView.ViewModel()
+
+        // WHEN
+        let groups = viewModel.groups
+
+        // THEN
+        #expect(groups.count == 4)
+        #expect(groups[0] == .today)
+        #expect(groups[1] == .upcoming)
+        #expect(groups[2] == .overdue)
+        #expect(groups[3] == .completed)
+    }
+
+    // MARK: Functions tests
+
+    @Test(
+        "count returns zero when empty data",
+        arguments: TodoGroup.allCases
+    )
+    func countWhenEmptyData(for group: TodoGroup) throws {
+        // GIVEN
+        let tasks: [Todo] = []
+        let viewModel = TaskGroupListView.ViewModel()
+
+        // WHEN
+        let count = viewModel.count(tasks, for: group)
+
+        // THEN
+        #expect(count == 0)
+    }
+
+    @Test(
+        "count returns correct count when filled data",
+        arguments: TodoGroup.allCases
+    )
+    func countWhenFilledData(for group: TodoGroup) throws {
+        // GIVEN
+        let today: Date = .now
+        let tomorrow = calendar.date(byAdding: .day, value: 1, to: today) ?? today
+        let yesterday = calendar.date(byAdding: .day, value: -1, to: today) ?? today
+        let nextWeek = calendar.date(byAdding: .day, value: 7, to: today) ?? today
+        let lastWeek = calendar.date(byAdding: .day, value: -7, to: today) ?? today
+
+        let tasks = [
+            Todo(title: "Today task #1", due: today),
+            Todo(title: "Today task #2", due: today),
+            Todo(title: "Tomorrow task #1", due: tomorrow),
+            Todo(title: "Next week task #1", due: nextWeek),
+            Todo(title: "Yesterday task #1", due: yesterday),
+            Todo(title: "Last week task #1", due: lastWeek),
+            Todo(title: "Completed task #1", due: tomorrow, completed: today),
+            Todo(title: "Completed task #2", due: yesterday, completed: today)
+        ]
+
+        let viewModel = TaskGroupListView.ViewModel()
+
+        // WHEN
+        let count = viewModel.count(tasks, for: group)
+
+        // THEN
+        #expect(count == 2)
+    }
+
+}