Implemented the NewTaskView view with its respective view model.

UnitTests/Tests/View Models/NewTaskViewModelTests.swift

@@ -0,0 +1,239 @@
+import Foundation
+import SwiftData
+import Testing
+
+@testable import Todos
+
+@Suite("NewTaskView ViewModel Tests")
+struct NewTaskViewModelTests {
+
+    // MARK: Initialization tests
+
+    @Test("View model initializes with default values")
+    func initialization() {
+        // GIVEN
+        // WHEN
+        let viewModel = NewTaskView.ViewModel()
+
+        // THEN
+        #expect(viewModel.title == "")
+        #expect(viewModel.note == "")
+        #expect(viewModel.due.timeIntervalSinceNow < 1.0)
+    }
+
+    // MARK: Properties tests
+
+    @Test("due property can be modified")
+    func dueModifications() {
+        // GIVEN
+        let dateInsert = Date(timeIntervalSince1970: 1000000000)
+        let dateUpdate = Date(timeIntervalSince1970: 2000000000)
+
+        // WHEN
+        let viewModel = NewTaskView.ViewModel()
+
+        // THEN
+        viewModel.due = dateInsert
+        #expect(viewModel.due == dateInsert)
+
+        viewModel.due = dateUpdate
+        #expect(viewModel.due == dateUpdate)
+    }
+
+    @Test("note property can be modified")
+    func noteModifications() {
+        // GIVEN
+        let noteInsert = "Initial note"
+        let noteUpdate = "Updated note"
+
+        // WHEN
+        let viewModel = NewTaskView.ViewModel()
+
+        // THEN
+        viewModel.note = noteInsert
+        #expect(viewModel.note == noteInsert)
+
+        viewModel.note = noteUpdate
+        #expect(viewModel.note == noteUpdate)
+    }
+
+    @Test("title property can be modified")
+    func titleModifications() {
+        // GIVEN
+        let titleInsert = "Initial title"
+        let titleUpdate = "Updated title"
+
+        // WHEN
+        let viewModel = NewTaskView.ViewModel()
+
+        // THEN
+        viewModel.title = titleInsert
+        #expect(viewModel.title == titleInsert)
+
+        viewModel.title = titleUpdate
+        #expect(viewModel.title == titleUpdate)
+    }
+
+    // MARK: Computed tests
+
+    @Test(
+        "canConfirm property validation",
+        arguments: zip(
+            ["", "Some title goes here...", "   "],
+            [false, true, false]
+        )
+    )
+    func canConfirm(
+        with title: String,
+        expects expectation: Bool
+    ) {
+        // GIVEN
+        let viewModel = NewTaskView.ViewModel()
+
+        // WHEN
+        viewModel.title = title
+
+        // THEN
+        #expect(viewModel.canConfirm == expectation)
+    }
+
+    @Test("canConfirm updates when title changes")
+    func canConfirmWithTitleChanges() {
+        // GIVEN
+        let titleEmpty = ""
+        let titleFilled = "New task"
+        let titleTrimmed = "  "
+
+        // WHEN
+        let viewModel = NewTaskView.ViewModel()
+
+        // THEN
+        viewModel.title = titleEmpty
+        #expect(viewModel.canConfirm == false)
+
+        viewModel.title = titleFilled
+        #expect(viewModel.canConfirm == true)
+
+        viewModel.title = titleTrimmed
+        #expect(viewModel.canConfirm == false)
+    }
+
+    // MARK: Functions tests
+
+    @Test("save creates todo with all properties")
+    @MainActor
+    func saveWithAllProperties() throws {
+        // GIVEN
+        let container = try ModelContainer(
+            for: Todo.self,
+            configurations: .init(isStoredInMemoryOnly: true)
+        )
+        let context = container.mainContext
+        let viewModel = NewTaskView.ViewModel()
+
+        // WHEN
+        viewModel.title = "Complete project"
+        viewModel.note = "Finish by end of week"
+        viewModel.due = Date(timeIntervalSince1970: 1000000000)
+
+        viewModel.save(to: context)
+
+        // THEN
+        let descriptor = FetchDescriptor<Todo>()
+        let todos = try context.fetch(descriptor)
+        let todo = try #require(todos.first)
+
+        #expect(todo.title == viewModel.title)
+        #expect(todo.note == viewModel.note)
+        #expect(todo.due == viewModel.due)
+        #expect(todo.completed == nil)
+    }
+
+    @Test("save creates todo without note when note is empty")
+    @MainActor
+    func saveWithEmptyNote() throws {
+        // GIVEN
+        let container = try ModelContainer(
+            for: Todo.self,
+            configurations: .init(isStoredInMemoryOnly: true)
+        )
+        let context = container.mainContext
+        let viewModel = NewTaskView.ViewModel()
+
+        // WHEN
+        viewModel.title = "Task without note"
+        viewModel.note = ""
+        viewModel.due = Date()
+
+        viewModel.save(to: context)
+
+        // THEN
+        let descriptor = FetchDescriptor<Todo>()
+        let todos = try context.fetch(descriptor)
+        let todo = try #require(todos.first)
+
+        #expect(todo.title == viewModel.title)
+        #expect(todo.note == nil)
+        #expect(todo.due == viewModel.due)
+        #expect(todo.completed == nil)
+    }
+
+    @Test("save creates todo with note containing only whitespace as nil")
+    @MainActor
+    func saveWithWhitespaceNote() throws {
+        // GIVEN
+        let container = try ModelContainer(
+            for: Todo.self,
+            configurations: .init(isStoredInMemoryOnly: true)
+        )
+        let context = container.mainContext
+        let viewModel = NewTaskView.ViewModel()
+
+        // WHEN
+        viewModel.title = "Task with whitespace note"
+        viewModel.note = "   "
+        viewModel.due = Date()
+
+        viewModel.save(to: context)
+
+        // THEN
+        let descriptor = FetchDescriptor<Todo>()
+        let todos = try context.fetch(descriptor)
+        let todo = try #require(todos.first)
+
+        #expect(todo.title == viewModel.title)
+        #expect(todo.note == nil)
+        #expect(todo.due == viewModel.due)
+        #expect(todo.completed == nil)
+    }
+
+    @Test("save inserts multiple todos independently")
+    @MainActor
+    func saveMultipleTodos() throws {
+        // GIVEN
+        let container = try ModelContainer(
+            for: Todo.self,
+            configurations: .init(isStoredInMemoryOnly: true)
+        )
+        let context = container.mainContext
+        let viewModelFirst = NewTaskView.ViewModel()
+        let viewModelSecond = NewTaskView.ViewModel()
+
+        // WHEN
+        viewModelFirst.title = "First task"
+        viewModelFirst.save(to: context)
+
+        viewModelSecond.title = "Second task"
+        viewModelSecond.note = "With a note"
+        viewModelSecond.save(to: context)
+
+        // THEN
+        let descriptor = FetchDescriptor<Todo>()
+        let todos = try context.fetch(descriptor)
+
+        #expect(todos.count == 2)
+        #expect(todos.contains { $0.title == "First task" })
+        #expect(todos.contains { $0.title == "Second task" })
+    }
+
+}