@Test public void shouldFailWhenFileDoesNotExist() throws Exception { FileStorage fileStorage = mock(FileStorage.class); when(fileStorage.exists("1/2/3")).thenReturn(false); BufferedLogReader logReader = new HessianBufferedLogReader(); logReader.setFileStorage(fileStorage); IllegalArgumentException expected = null; try { logReader.read("1", "2", "3", Integer.class); } catch (IllegalArgumentException e) { expected = e; } assertThat(expected, notNullValue()); verify(fileStorage).exists("1/2/3"); }