### Question:
HockeyApp implements CrashReportHandler { @Override public void sendStacktrace(String feedback, String stacktrace) throws IOException { crashClient.sendStacktrace(feedback, stacktrace); } HockeyApp(FeedbackClient feedbackClient, CrashReporterClient crashClient); @Override void sendFeedback(String feedback, String name, String email); @Override void sendStacktrace(String feedback, String stacktrace);  }### Answer:
@Test public void sendCrashReport() throws IOException { CrashReporterClient crash = (feedback, stacktrace1) -> { assertEquals(feedbackText, feedback); assertEquals(stacktrace1, stacktrace1); }; HockeyApp app = new HockeyApp(null, crash); app.sendStacktrace(feedbackText, stacktrace); }