Add a cancel job button

If you schedule a job you might change your mind or circumstances might
change. So you need to be able to cancel it. This commit adds a button
on the job page which hits the `…/cancel` API endpoint for a job.

tests/app/main/views/test_jobs.py

@@ -147,6 +147,28 @@ def test_should_show_scheduled_job(
         assert response.status_code == 200
         page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
         assert page.find('main').find_all('p')[2].text.strip() == 'Sending will start at midnight'
+        assert page.find('input', {'type': 'submit', 'value': 'Cancel sending'})
+
+
+def test_should_cancel_job(
+    app_,
+    service_one,
+    active_user_with_permissions,
+    fake_uuid,
+    mocker
+):
+    with app_.test_request_context(), app_.test_client() as client:
+        client.login(active_user_with_permissions, mocker, service_one)
+        mock_cancel = mocker.patch('app.main.jobs.job_api_client.cancel_job')
+        response = client.post(url_for(
+            'main.cancel_job',
+            service_id=service_one['id'],
+            job_id=fake_uuid
+        ))
+
+        mock_cancel.assert_called_once_with(service_one['id'], fake_uuid)
+        assert response.status_code == 302
+        assert response.location == url_for('main.service_dashboard', service_id=service_one['id'], _external=True)
 
 
 def test_should_not_show_cancelled_job(

tests/app/notify_client/test_job_client.py

@@ -361,3 +361,15 @@ def test_client_parses_empty_job_stats_for_service(mocker):
     assert result['data'][1]['notifications_sent'] == 0
     assert result['data'][1]['notification_count'] == 40
     assert result['data'][1]['notifications_failed'] == 0
+
+
+def test_cancel_job(mocker):
+
+    mock_post = mocker.patch('app.notify_client.job_api_client.JobApiClient.post')
+
+    JobApiClient().cancel_job('service_id', 'job_id')
+
+    mock_post.assert_called_once_with(
+        url='/service/{}/job/{}/cancel'.format('service_id', 'job_id'),
+        data={}
+    )