feat: add NSTextField validation support

Author: ns-vasilev

Sources/ValidatorUI/Classes/AppKit/Extensions/NSTextField+Validation.swift

@@ -0,0 +1,50 @@
+//
+// Validator
+// Copyright © 2023 Space Code. All rights reserved.
+//
+
+#if os(macOS)
+    import AppKit
+
+    extension NSTextField: IUIValidatable {
+        /// The value of the text field to validate.
+        /// Returns an empty string if `text` is nil.
+        public var inputValue: String { stringValue }
+
+        /// The type of input for validation.
+        public typealias Input = String
+
+        /// Enables or disables automatic validation when the text changes.
+        ///
+        /// - Parameter isEnabled: If true, validation is triggered on every text change.
+        ///                        If false, the target-action is removed.
+        public func validateOnInputChange(isEnabled: Bool) {
+            if isEnabled {
+                NotificationCenter.default.addObserver(
+                    self,
+                    selector: #selector(textFieldDidChange(_:)),
+                    name: NSControl.textDidChangeNotification,
+                    object: self
+                )
+            } else {
+                NotificationCenter.default.removeObserver(
+                    self,
+                    name: NSControl.textDidChangeNotification,
+                    object: self
+                )
+            }
+        }
+
+        // MARK: Private
+
+        /// Called automatically when the text field changes (if `validateOnInputChange` is enabled).
+        /// Performs validation using all rules stored in `validationRules`.
+        ///
+        /// - Parameter notification: The notification containing the text field.
+        @objc
+        private func textFieldDidChange(_ notification: Notification) {
+            guard notification.object as? NSTextField === self else { return }
+            validate(rules: validationRules)
+        }
+    }
+#endif

Tests/ValidatorUITests/UnitTests/AppKit/NSTextFieldTests.swift

@@ -0,0 +1,73 @@
+//
+// Validator
+// Copyright © 2023 Space Code. All rights reserved.
+//
+
+import ValidatorCore
+import ValidatorUI
+import XCTest
+
+#if canImport(AppKit)
+    import AppKit
+#endif
+
+#if os(macOS)
+    final class NSTextFieldTests: XCTestCase {
+        // MARK: Tests
+
+        @MainActor
+        func test_thatTextFieldValidationReturnsValid_whenInputValueIsValid() {
+            // given
+            let textField = NSTextField()
+
+            textField.validateOnInputChange(isEnabled: true)
+            textField.add(rule: LengthValidationRule(max: .max, error: String.error))
+
+            // when
+            textField.stringValue = String(String.text.prefix(.max))
+
+            var result: ValidationResult?
+
+            textField.validationHandler = { result = $0 }
+            textField.validate(rules: textField.validationRules)
+
+            // when
+            if case .valid = result {}
+            else { XCTFail("The result must be equal to the valid value") }
+        }
+
+        @MainActor
+        func test_thatTextFieldValidationReturnsInvalid_whenInputValueIsInvalid() {
+            // given
+            let textField = NSTextField()
+
+            textField.validateOnInputChange(isEnabled: true)
+            textField.add(rule: LengthValidationRule(max: .max, error: String.error))
+
+            // when
+            textField.stringValue = .text
+
+            var result: ValidationResult?
+
+            textField.validationHandler = { result = $0 }
+            textField.validate(rules: textField.validationRules)
+
+            // when
+            if case let .invalid(errors) = result {
+                XCTAssertEqual(errors.count, 1)
+                XCTAssertEqual(errors.first?.message, .error)
+            } else { XCTFail("The result must be equal to the invalid value") }
+        }
+    }
+
+    private extension String {
+        static let text: String = "lorem ipsum lorem ipsum lorem ipsum"
+        static let error: String = "error"
+    }
+
+    private extension Int {
+        static let min = 0
+        static let max = 10
+    }
+
+#endif