Unit testing the onPageStarted and onPageFinished of a WebView's WebViewClient callbacks

Android Studio 3.5.1
Kotlin 1.3

I have the following method that I am trying to unit test. That uses the WebView and WebViewClient

The method I have is the following that needs to be unit tested:

fun setPageStatus(webView: WebView?, pageStatus: (PageStatusResult) -> Unit) {
    webView?.webViewClient = object : WebViewClient() {

        override fun onPageStarted(view: WebView?, url: String?, favicon: Bitmap?) {
            pageStatus(PageStatusResult.PageStarted(url ?: "", favicon))
        }

        override fun onPageFinished(view: WebView?, url: String?) {
            pageStatus(PageStatusResult.PageFinished(url ?: ""))
        }
    }
}

I takes a webView that overrides some callback from the WebViewClient. And then calls a lambda function in the onPageStarted or onPageFinished.

Uses a sealed class to set the properties that is passed in the lambda method

sealed class PageStatusResult {
    data class PageFinished(val url: String) : PageStatusResult()
    data class PageStarted(val url: String, val favicon: Bitmap?) : PageStatusResult()
}

In the unit test I have do something like this:

@Test
fun `should set the correct settings of the WebView`() {
    // Arrange the webView
    val webView = WebView(RuntimeEnvironment.application.baseContext)

    // Act by calling the setPageStatus
    webFragment.setPageStatus(webView) { pageStatusResult ->
        when(pageStatusResult) {
            is PageStarted -> {
            // Assert that the url is correct
                assertThat(pageStatusResult.url).isEqualToIgnoringCase("http://google.com")
            }
        }
    }

    // Call the onPageStarted on the webViewClient and and assert in the when statement
    webView.webViewClient.onPageStarted(webView, "http://google.com", null)
}

from Unit testing the onPageStarted and onPageFinished of a WebView's WebViewClient callbacks