Introduce rendering matching espresso rule

[rjrjr]

Find a home for this. Ideally the same place that we share whatever idling resource cleverness that we've been hoarding.

/**
 * Base class for matchers that examine the workflow [Screen] [shown][View.getScreen]
 * by a [View].
 */
abstract class WorkflowScreenMatcher : TypeSafeMatcher<View>() {

  final override fun matchesSafely(item: View): Boolean {
    return item.getScreen()?.let { matchesScreen(it) } == true
  }

  protected abstract fun matchesScreen(rendering: Screen): Boolean
}

/**
 * Matches [View]s showing workflow [Screen]s that have [compatibility keys][Compatible.keyFor]
 * that include [string].
 */
fun withScreenWithKeyContaining(string: String): Matcher<View> {
  return withScreenWithKey(containsString(string))
}

/**
 * Matches [View]s showing workflow [Screen]s that have [compatibility keys][Compatible.keyFor]
 * that match [stringMatcher].
 */
fun withScreenWithKey(stringMatcher: Matcher<String>): Matcher<View> {
  return WorkflowScreenWithKeyMatcher(stringMatcher)
}

private class WorkflowScreenWithKeyMatcher(
  private val stringMatcher: Matcher<String>
) : WorkflowScreenMatcher() {
  override fun describeTo(description: Description) {
    description.appendText("with Screen with compatibility key: ")
    stringMatcher.describeTo(description)
  }

  override fun matchesScreen(rendering: Screen): Boolean {
    return stringMatcher.matches(Compatible.keyFor(rendering))
  }
}