Swift jest expectations (https://jestjs.io/docs/en/expect)

SwiftJestTests.swift

import XCTest
@testable import SampleApp

final class SampleAppTests: XCTestCase {

    func testExample() {
        expect("myValue").not().toBeNil()
      
        expect(5).toBe(5)
      
        expect(5)
          .withMessage("my test failure message")
          .not()
          .toBe(10)
    }

}

XCTestCase+Matcher.swift

import XCTest

extension XCTestCase {

    func expect<T: Equatable>(_ value: T) -> Matcher<T> {
        return Matcher(expectedBase: value)
    }
}

extension XCTestCase {
    class Matcher<T: Equatable> {
        private let expectedBase: T
        private var isNegated = false
        private var message: (() -> String)?

        init(expectedBase: T) {
            self.expectedBase = expectedBase
        }

        func withMessage(_ message: @escaping @autoclosure () -> String) -> Self {
            self.message = message

            return self
        }

        func not() -> Self {
            isNegated = true

            return self
        }

        func toBe(_ otherValue: T) {
            if isNegated {
                XCTAssertNotEqual(expectedBase, otherValue, message?() ?? "")
            } else {
                XCTAssertEqual(expectedBase, otherValue, message?() ?? "")

            }
        }

        func toBeNil() {
            if isNegated {
                XCTAssertNotNil(expectedBase, message?() ?? "")
            } else {
                XCTAssertNil(expectedBase, message?() ?? "")
            }
        }
    }
}