Test your methods in playground through XCTestCase

Playground Validation

import XCTest

//  Sample class with one method in it.
class evenOddClass {

    func isEvenNumber(_ number: Int) -> Bool {
        if number % 2 == 0 {
            return true
        } else {
            return false
        }
    }
}

// Sample test target class to check your functions.
class tests: XCTestCase {
    var evenOddClassObj = evenOddClass()

    func test1() {
        XCTAssertEqual(evenOddClassObj.isEvenNumber(4), true)
    }

    func test2() {
        XCTAssertEqual(evenOddClassObj.isEvenNumber(5), true)
    }
}

tests.defaultTestSuite.run()