Ensure correct selected nav item on broadcast page

Once a broadcast has been submitted for approval it either lives on the
‘Current alerts’ or ‘Previous alerts’ page, depending on where it is
in its lifecycle.

Therefore when clicking into a broadcast from one of those pages the
same navigation item should remain selected.

Because we select the navigation items based on the request endpoint,
this means we need an endpoint for each navigation page, even if the
content of the pages will be the same in both cases.

This commit adds the two new end points, removes the old, single
endpoint and updates links to point to the new endpoint.

tests/app/main/views/test_broadcast.py

@@ -52,9 +52,13 @@ sample_uuid = sample_uuid()
         403, 403,
     ),
     (
-        '.view_broadcast_message', {'broadcast_message_id': sample_uuid},
+        '.view_current_broadcast', {'broadcast_message_id': sample_uuid},
         403, 403,
     ),
+    (
+        '.view_previous_broadcast', {'broadcast_message_id': sample_uuid},
+        403, 405,
+    ),
     (
         '.cancel_broadcast_message', {'broadcast_message_id': sample_uuid},
         403, 403,
@@ -1019,7 +1023,7 @@ def test_start_broadcasting(
         service_id=SERVICE_ONE_ID,
         broadcast_message_id=fake_uuid,
         _expected_redirect=url_for(
-            'main.view_broadcast_message',
+            'main.view_current_broadcast',
             service_id=SERVICE_ONE_ID,
             broadcast_message_id=fake_uuid,
             _external=True,
@@ -1099,7 +1103,7 @@ def test_view_broadcast_message_page(
     service_one['permissions'] += ['broadcast']
 
     page = client_request.get(
-        '.view_broadcast_message',
+        '.view_current_broadcast',
         service_id=SERVICE_ONE_ID,
         broadcast_message_id=fake_uuid,
     )
@@ -1136,7 +1140,7 @@ def test_view_pending_broadcast(
     service_one['permissions'] += ['broadcast']
 
     page = client_request.get(
-        '.view_broadcast_message',
+        '.view_current_broadcast',
         service_id=SERVICE_ONE_ID,
         broadcast_message_id=fake_uuid,
     )
@@ -1190,7 +1194,7 @@ def test_cant_approve_own_broadcast(
     service_one['permissions'] += ['broadcast']
 
     page = client_request.get(
-        '.view_broadcast_message',
+        '.view_current_broadcast',
         service_id=SERVICE_ONE_ID,
         broadcast_message_id=fake_uuid,
     )
@@ -1243,7 +1247,7 @@ def test_can_approve_own_broadcast_in_trial_mode(
     service_one['permissions'] += ['broadcast']
 
     page = client_request.get(
-        '.view_broadcast_message',
+        '.view_current_broadcast',
         service_id=SERVICE_ONE_ID,
         broadcast_message_id=fake_uuid,
     )
@@ -1319,7 +1323,7 @@ def test_view_only_user_cant_approve_broadcast(
     service_one['permissions'] += ['broadcast']
 
     page = client_request.get(
-        '.view_broadcast_message',
+        '.view_current_broadcast',
         service_id=SERVICE_ONE_ID,
         broadcast_message_id=fake_uuid,
     )
@@ -1338,7 +1342,7 @@ def test_view_only_user_cant_approve_broadcast(
 @pytest.mark.parametrize('trial_mode, initial_status, expected_approval, expected_redirect', (
     (True, 'draft', False, partial(
         url_for,
-        '.view_broadcast_message',
+        '.view_current_broadcast',
         broadcast_message_id=sample_uuid,
     )),
     (True, 'pending-approval', True, partial(
@@ -1348,22 +1352,22 @@ def test_view_only_user_cant_approve_broadcast(
     )),
     (False, 'pending-approval', True, partial(
         url_for,
-        '.view_broadcast_message',
+        '.view_current_broadcast',
         broadcast_message_id=sample_uuid,
     )),
     (True, 'rejected', False, partial(
         url_for,
-        '.view_broadcast_message',
+        '.view_current_broadcast',
         broadcast_message_id=sample_uuid,
     )),
     (True, 'broadcasting', False, partial(
         url_for,
-        '.view_broadcast_message',
+        '.view_current_broadcast',
         broadcast_message_id=sample_uuid,
     )),
     (True, 'cancelled', False, partial(
         url_for,
-        '.view_broadcast_message',
+        '.view_current_broadcast',
         broadcast_message_id=sample_uuid,
     )),
 ))
@@ -1396,7 +1400,7 @@ def test_request_approval(
     service_one['permissions'] += ['broadcast']
 
     client_request.post(
-        '.view_broadcast_message',
+        '.view_current_broadcast',
         service_id=SERVICE_ONE_ID,
         broadcast_message_id=fake_uuid,
         _expected_redirect=expected_redirect(
@@ -1502,7 +1506,7 @@ def test_cant_reject_broadcast_in_wrong_state(
         service_id=SERVICE_ONE_ID,
         broadcast_message_id=fake_uuid,
         _expected_redirect=url_for(
-            '.view_broadcast_message',
+            '.view_current_broadcast',
             service_id=SERVICE_ONE_ID,
             broadcast_message_id=fake_uuid,
             _external=True,
@@ -1513,15 +1517,20 @@ def test_cant_reject_broadcast_in_wrong_state(
     assert mock_update_broadcast_message_status.called is False
 
 
+@pytest.mark.parametrize('endpoint', (
+    '.view_current_broadcast',
+    '.view_previous_broadcast',
+))
 def test_no_view_page_for_draft(
     client_request,
     service_one,
     mock_get_draft_broadcast_message,
     fake_uuid,
+    endpoint,
 ):
     service_one['permissions'] += ['broadcast']
     client_request.get(
-        '.view_broadcast_message',
+        endpoint,
         service_id=SERVICE_ONE_ID,
         broadcast_message_id=fake_uuid,
         _expected_status=404,
@@ -1574,7 +1583,7 @@ def test_confirm_cancel_broadcast(
         service_id=SERVICE_ONE_ID,
         broadcast_message_id=fake_uuid,
         _expected_redirect=url_for(
-            '.view_broadcast_message',
+            '.view_previous_broadcast',
             service_id=SERVICE_ONE_ID,
             broadcast_message_id=fake_uuid,
             _external=True,
@@ -1602,7 +1611,7 @@ def test_cant_cancel_broadcast_in_a_different_state(
         service_id=SERVICE_ONE_ID,
         broadcast_message_id=fake_uuid,
         _expected_redirect=url_for(
-            '.view_broadcast_message',
+            '.view_current_broadcast',
             service_id=SERVICE_ONE_ID,
             broadcast_message_id=fake_uuid,
             _external=True,