Add tests for time_left

This commit extracts the code that works out the ‘Data available for…’
message so that it’s easy to unit test for.

app/main/views/jobs.py

@@ -320,19 +320,23 @@ def get_job_partials(job):
                 status=request.args.get('status', '')
             ),
             help=get_help_argument(),
-            time_left=ago.human(
-                (
-                    datetime.now(timezone.utc).replace(hour=23, minute=59, second=59)
-                ) - (
-                    dateutil.parser.parse(job['created_at']) + timedelta(days=8)
-                ),
-                future_tense='Data available for {}',
-                past_tense='Was available {} ago',  # No-one should ever see this
-                precision=1
-            )
+            time_left=get_time_left(job['created_at'])
         ),
         'status': render_template(
             'partials/jobs/status.html',
             job=job
         ),
     }
+
+
+def get_time_left(job_created_at):
+    return ago.human(
+        (
+            datetime.now(timezone.utc).replace(hour=23, minute=59, second=59)
+        ) - (
+            dateutil.parser.parse(job_created_at) + timedelta(days=8)
+        ),
+        future_tense='Data available for {}',
+        past_tense='Data no longer available',  # No-one should ever see this
+        precision=1
+    )

tests/app/main/views/test_jobs.py

@@ -3,6 +3,7 @@ from flask import url_for
 from bs4 import BeautifulSoup
 import json
 from app.utils import generate_notifications_csv
+from app.main.views.jobs import get_time_left
 from tests import (notification_json, job_json)
 from tests.conftest import fake_uuid
 from tests.conftest import mock_get_job as mock_get_job1
@@ -300,3 +301,16 @@ def test_should_download_notifications_for_a_job(app_,
         assert response.get_data(as_text=True) == csv_content
         assert 'text/csv' in response.headers['Content-Type']
         assert 'sample template - 1 January at 11:09.csv"' in response.headers['Content-Disposition']
+
+
+@pytest.mark.parametrize(
+    "job_created_at, expected_message", [
+        ("2016-01-10 11:09:00.000000+00:00", "Data available for 7 days"),
+        ("2016-01-04 11:09:00.000000+00:00", "Data available for 1 day"),
+        ("2016-01-03 11:09:00.000000+00:00", "Data available for 11 hours"),
+        ("2016-01-02 23:59:59.000000+00:00", "Data no longer available")
+    ]
+)
+@freeze_time("2016-01-10 12:00:00.000000")
+def test_time_left(job_created_at, expected_message):
+    assert get_time_left(job_created_at) == expected_message