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" : {

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 }
+
+}

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