test_doubles__fakes.kt

@Test fun `going back restores the previously visited URL`() {
    val browser = Browser(FakeHistory())
    browser.visit(URL("https://www.le0nidas.gr"))
    browser.visit(URL("https://www.google.com"))

    browser.back()

    assertThat(browser.activeURL, equalTo(URL("https://www.le0nidas.gr")))
}

private class FakeHistory : History {

    private val urls = mutableListOf<URL>()

    override fun push(url: URL) {
        urls.add(0, url)
    }

    override fun pop(): URL {
        return urls.removeAt(0)
    }

    override fun peek(): URL {
        return urls[0]
    }
}