Stop blank strings being inserted as inbound numbers

We had an inbound number in the database with a value of ''. This
could happen if there are blank lines in the inbound numbers file
we use for the `insert-inbound-numbers` command. To avoid this
happening again, the command now calls `.strip()` on each line of the
file and only inserts a row if the result is truthy (i.e. not '').

app/commands.py

@@ -246,14 +246,15 @@ def fix_notification_statuses_not_in_sync():
               one number per line. The number must have the format of 07... not 447....""")
 def insert_inbound_numbers_from_file(file_name):
     print("Inserting inbound numbers from {}".format(file_name))
-    file = open(file_name)
-    sql = "insert into inbound_numbers values('{}', '{}', 'mmg', null, True, now(), null);"
+    with open(file_name) as file:
+        sql = "insert into inbound_numbers values('{}', '{}', 'mmg', null, True, now(), null);"
 
-    for line in file:
-        print(line)
-        db.session.execute(sql.format(uuid.uuid4(), line.strip()))
-        db.session.commit()
-    file.close()
+        for line in file:
+            line = line.strip()
+            if line:
+                print(line)
+                db.session.execute(sql.format(uuid.uuid4(), line))
+                db.session.commit()
 
 
 @notify_command(name='replay-create-pdf-for-templated-letter')

tests/app/test_commands.py

@@ -1,8 +1,23 @@
-from app.commands import local_dev_broadcast_permissions
+from app.commands import (
+    insert_inbound_numbers_from_file,
+    local_dev_broadcast_permissions,
+)
+from app.dao.inbound_numbers_dao import dao_get_available_inbound_numbers
 from app.dao.services_dao import dao_add_user_to_service
 from tests.app.db import create_user
 
 
+def test_insert_inbound_numbers_from_file(notify_db_session, notify_api, tmpdir):
+    numbers_file = tmpdir.join("numbers.txt")
+    numbers_file.write("07700900373\n07700900473\n07700900375\n\n\n\n")
+
+    notify_api.test_cli_runner().invoke(insert_inbound_numbers_from_file, ['-f', numbers_file])
+
+    inbound_numbers = dao_get_available_inbound_numbers()
+    assert len(inbound_numbers) == 3
+    assert set(x.number for x in inbound_numbers) == {'07700900373', '07700900473', '07700900375'}
+
+
 def test_local_dev_broadcast_permissions(
     sample_service,
     sample_broadcast_service,