### Question:
SpywarePluginLayer implements Closeable { public void documentChange(DocumentInfo info) { documentHandler.handleEvent(info); } SpywarePluginLayer(ActiveThreadSet activeThreads, EventReceiver receiver, SnapshotTaker taker,
            DocumentChangeHandler documentHandler); void takeSnapshot(SnapshotInfo info); void documentChange(DocumentInfo info); @Override void close();  }### Answer:
@Test public void documentChangeAsksDocumentHandlerToHandleEvent() { DocumentInfo info = mock(DocumentInfo.class); spl.documentChange(info); verify(documentHandler, times(1)).handleEvent(info); }