Fixed issues encountered in the unit tests target after the project transitioned to Swift 6 and strict concurrency.

UnitTests/Tests/Enumerations/TodoGroupTests.swift

@@ -3,6 +3,7 @@ import Testing
 
 @testable import Todos
 
+@MainActor
 @Suite("TodoGroup enumeration tests")
 struct TodoGroupTests {
 
@@ -11,7 +12,7 @@ struct TodoGroupTests {
     @Test(
         "canShowCompleted returns correct values",
         arguments: zip(
-            TodoGroup.allCases,
+            [TodoGroup.today, .upcoming, .overdue, .completed],
             [true, true, true, false]
         )
     )
@@ -30,7 +31,7 @@ struct TodoGroupTests {
     @Test(
         "canReorder returns correct values",
         arguments: zip(
-            TodoGroup.allCases,
+            [TodoGroup.today, .upcoming, .overdue, .completed],
             [true, true, true, false]
         )
     )
@@ -49,7 +50,7 @@ struct TodoGroupTests {
     @Test(
         "group color match expected values",
         arguments: zip(
-            TodoGroup.allCases,
+            [TodoGroup.today, .upcoming, .overdue, .completed],
             [Color.blue, .green, .red, .gray]
         )
     )
@@ -68,7 +69,7 @@ struct TodoGroupTests {
     @Test(
         "group icon names match expected values",
         arguments: zip(
-            TodoGroup.allCases,
+            [TodoGroup.today, .upcoming, .overdue, .completed],
             ["calendar.badge.clock", "calendar", "calendar.badge.exclamationmark", "checkmark.circle.fill"]
         )
     )
@@ -87,7 +88,7 @@ struct TodoGroupTests {
     @Test(
         "group titles match expected values",
         arguments: zip(
-            TodoGroup.allCases,
+            [TodoGroup.today, .upcoming, .overdue, .completed],
             ["today", "upcoming", "overdue", "completed"]
         )
     )
@@ -123,7 +124,10 @@ struct TodoGroupTests {
 
     // MARK: Identifiable Tests
 
-    @Test("id returns an identity of a case", arguments: TodoGroup.allCases)
+    @Test(
+        "id returns an identity of a case",
+        arguments: [TodoGroup.today, .upcoming, .overdue, .completed]
+    )
     func id(for group: TodoGroup) {
         // GIVEN
         // WHEN