@Test
  public void shouldSendMessage() {
    String message = "A message";
    provider.send(message);

    ArgumentCaptor<SendMessageRequest> argument = ArgumentCaptor.forClass(SendMessageRequest.class);
    verify(sqsClient, times(1)).sendMessage(argument.capture());

    SendMessageRequest request = argument.getValue();
    assertThat(request.getMessageBody(), equalTo(message));
  }