LineBlobClientImpl implements LineBlobClient { @Override public CompletableFuture<BotApiResponse> setRichMenuImage( final String richMenuId, final String contentType, final byte[] content) { final RequestBody requestBody = RequestBody.create(MediaType.parse(contentType), content); return LineMessagingClientImpl.toBotApiFuture( retrofitImpl.uploadRichMenuImage(richMenuId, requestBody)); }  @Override CompletableFuture<MessageContentResponse> getMessageContent(final String messageId); @Override CompletableFuture<MessageContentResponse> getRichMenuImage(final String richMenuId); @Override CompletableFuture<BotApiResponse> setRichMenuImage(
            final String richMenuId, final String contentType, final byte[] content);  }
@Test public void uploadRichMenuImageTest() throws Exception { whenCall(retrofitMock.uploadRichMenuImage(any(), any()), null); final BotApiResponse botApiResponse = target.setRichMenuImage("ID", "image/jpeg", ZERO_BYTES).get(); verify(retrofitMock, only()) .uploadRichMenuImage(eq("ID"), any()); assertThat(botApiResponse).isEqualTo(BOT_API_SUCCESS_RESPONSE); }