Todos demo: fix sorting filtered todos (#1404)

* Todos demo: fix sorting filtered todos

* wip

* Update TodosTests.swift

(cherry picked from commit 3ba71b9787d1500fb35a322444cf990c801d5e08)

Author: stephencelis

Examples/Todos/Todos/Todos.swift

@@ -67,14 +67,16 @@ let appReducer = Reducer<AppState, AppAction, AppEnvironment>.combine(
       return .none
 
     case var .move(source, destination):
-      if state.filter != .all {
+      if state.filter == .completed {
         source = IndexSet(
           source
             .map { state.filteredTodos[$0] }
             .compactMap { state.todos.index(id: $0.id) }
         )
         destination =
-          state.todos.index(id: state.filteredTodos[destination].id)
+          (destination < state.filteredTodos.endIndex
+            ? state.todos.index(id: state.filteredTodos[destination].id)
+            : state.todos.endIndex)
           ?? destination
       }
 

Examples/Todos/TodosTests/TodosTests.swift

@@ -264,12 +264,12 @@ final class TodosTests: XCTestCase {
         TodoState(
           description: "",
           id: UUID(uuidString: "00000000-0000-0000-0000-000000000001")!,
-          isComplete: true
+          isComplete: false
         ),
         TodoState(
           description: "",
           id: UUID(uuidString: "00000000-0000-0000-0000-000000000002")!,
-          isComplete: false
+          isComplete: true
         ),
         TodoState(
           description: "",
@@ -293,12 +293,12 @@ final class TodosTests: XCTestCase {
     await store.send(.filterPicked(.completed)) {
       $0.filter = .completed
     }
-    await store.send(.move([0], 1)) {
+    await store.send(.move([0], 2)) {
       $0.todos = [
         $0.todos[0],
-        $0.todos[2],
         $0.todos[1],
         $0.todos[3],
+        $0.todos[2],
       ]
     }
     await self.mainQueue.advance(by: .milliseconds(100))