feat: add no-whitespace validation rule (#83)

Author: ns-vasilev

README.md

@@ -310,6 +310,7 @@ struct RegistrationView: View {
 | `CharactersValidationRule` | Validates that a string contains only characters from the allowed CharacterSet | `CharactersValidationRule(characterSet: .letters, error: "Invalid characters")` |
 | `NilValidationRule` | Validates that value is nil | `NilValidationRule(error: "Value must be nil")`
 | `PositiveNumberValidationRule` | Validates that value is positive | `PositiveNumberValidationRule(error: "Value must be positive")`
+| `NoWhitespaceValidationRule` | Validates that a string does not contain any whitespace characters | `NoWhitespaceValidationRule(error: "Spaces are not allowed")`
 
 ## Custom Validators
 

Sources/ValidatorCore/Classes/Rules/NoWhitespaceValidationRule.swift

@@ -0,0 +1,39 @@
+//
+// Validator
+// Copyright © 2025 Space Code. All rights reserved.
+//
+
+/// Validates that a string does not contain any whitespace characters.
+///
+/// # Example:
+/// ```swift
+/// let rule = NoWhitespaceValidationRule(error: "Spaces are not allowed")
+/// rule.validate(input: "lorem lorem") // false
+/// rule.validate(input: "Text") // true
+/// ```
+public struct NoWhitespaceValidationRule: IValidationRule {
+    // MARK: Types
+
+    public typealias Input = String
+
+    // MARK: Properties
+
+    /// The validation error.
+    public let error: IValidationError
+
+    // MARK: Initialization
+
+    /// Initializes a characters validation rule.
+    ///
+    /// - Parameters:
+    ///   - error: The validation error to return if input fails validation.
+    public init(error: IValidationError) {
+        self.error = error
+    }
+
+    // MARK: IValidationRule
+
+    public func validate(input: String) -> Bool {
+        input.rangeOfCharacter(from: .whitespacesAndNewlines) == nil
+    }
+}

Sources/ValidatorCore/Validator.docc/Overview.md

@@ -33,6 +33,7 @@ ValidatorCore contains all core validation rules, utilities, and mechanisms for
 - ``URLValidationRule``
 - ``NilValidationRule``
 - ``PositiveNumberValidationRule``
+- ``NoWhitespaceValidationRuleTests``
 
 ### Articles
 

Tests/ValidatorCoreTests/UnitTests/Rules/NoWhitespaceValidationRuleTests.swift

@@ -0,0 +1,96 @@
+//
+// Validator
+// Copyright © 2025 Space Code. All rights reserved.
+//
+
+import ValidatorCore
+import XCTest
+
+// MARK: - NoWhitespaceValidationRuleTests
+
+final class NoWhitespaceValidationRuleTests: XCTestCase {
+    // MARK: Properties
+
+    private var sut: NoWhitespaceValidationRule!
+
+    // MARK: XCTestCase
+
+    override func setUp() {
+        super.setUp()
+        sut = NoWhitespaceValidationRule(error: String.error)
+    }
+
+    override func tearDown() {
+        sut = nil
+        super.tearDown()
+    }
+
+    // MARK: Tests
+
+    func test_thatNoWhitespaceValidationRuleSetsProperties() {
+        // then
+        XCTAssertEqual(sut.error.message, .error)
+    }
+
+    func test_thatNoWhitespaceValidationRuleValidatesInput_whenInputIsCorrectValue() {
+        // when
+        let result = sut.validate(input: "text")
+
+        // then
+        XCTAssertTrue(result)
+    }
+
+    func test_thatNoWhitespaceValidationRuleValidatesInput_whenInputIsIncorrectValue() {
+        // when
+        let result = sut.validate(input: .error)
+
+        // then
+        XCTAssertFalse(result)
+    }
+
+    func test_thatNoWhitespaceValidationRuleFails_whenInputContainsSpace() {
+        // when
+        let result = sut.validate(input: "hello world")
+
+        // then
+        XCTAssertFalse(result)
+    }
+
+    func test_thatNoWhitespaceValidationRuleFails_whenInputContainsTab() {
+        // when
+        let result = sut.validate(input: "hello\tworld")
+
+        // then
+        XCTAssertFalse(result)
+    }
+
+    func test_thatNoWhitespaceValidationRuleFails_whenInputContainsNewline() {
+        // when
+        let result = sut.validate(input: "hello\nworld")
+
+        // then
+        XCTAssertFalse(result)
+    }
+
+    func test_thatNoWhitespaceValidationRulePasses_whenInputIsEmptyString() {
+        // when
+        let result = sut.validate(input: "")
+
+        // then
+        XCTAssertTrue(result)
+    }
+
+    func test_thatNoWhitespaceValidationRulePasses_whenInputContainsSymbolsOnly() {
+        // when
+        let result = sut.validate(input: "!@#$%^&*()")
+
+        // then
+        XCTAssertTrue(result)
+    }
+}
+
+// MARK: - Constants
+
+private extension String {
+    static let error = "Spaces are not allowed"
+}