new_contents: from datetime import datetime
  
  from django.core.management import call_command
  
  import pytest
  
  
  @pytest.mark.django_db
  def test_postlinks_command_friday(share, mocker):
      mocked = mocker.patch('amweekly.slack.jobs.process_incoming_webhook.delay')
      mocked_dt = mocker.patch('amweekly.management.commands.postlinks.datetime.datetime')  # noqa
      mocked_dt.utcnow.return_value = datetime(2017, 6, 23)  # FRIDAY
      call_command('postlinks')
      assert mocked.called
  
  
  @pytest.mark.django_db
  def test_postlinks_command_not_friday(share, mocker):
      mocked = mocker.patch('amweekly.slack.jobs.process_incoming_webhook.delay')
      call_command('postlinks')
      assert not mocked.called
  
subject: add tests for postlinks