class ExampleTest: XCTestCase {
…
  func test_onInitialisation_getCurrentValue_returns_zero() {
        let object = Object()
        XCTAssertEqual(object.getCurrentValue(), 0)
    }
…
}

or

class ExampleTestCase: XCTestCase {

    var object: Object!

    override func setUp() {
        super.setUp()
        object = Object()
    }

    override func tearDown() {
        object = nil
        super.tearDown()
    }
…
}