Fix test and LGTM warnings.

- Fixes LGTM warnings for an unused import and equality comparisons to
  None in SQLAlchemy filters.
- Removes part of a unit test asserting that the claimed_until locking
  mechanism works correctly. If I recall correctly, this does not work
  in unit tests because the test takes place inside a transaction, and
  the database provider does evaluate the current time until the
  transaction is written.

alembic/versions/07e0598199f6_add_applications_claimed_until.py

@@ -7,7 +7,6 @@ Create Date: 2020-01-25 13:33:17.711548
 """
 from alembic import op
 import sqlalchemy as sa
-from sqlalchemy.dialects import postgresql
 
 # revision identifiers, used by Alembic.
 revision = '07e0598199f6' # pragma: allowlist secret

atst/domain/applications.py

@@ -134,11 +134,11 @@ class Applications(BaseDomainClass):
             .join(PortfolioStateMachine)
             .filter(PortfolioStateMachine.state == FSMStates.COMPLETED)
             .filter(Application.deleted == False)
-            .filter(Application.cloud_id == None)
+            .filter(Application.cloud_id.is_(None))
             .filter(
                 or_(
-                    Application.claimed_until == None,
-                    Application.claimed_until >= func.now(),
+                    Application.claimed_until.is_(None),
+                    Application.claimed_until <= func.now(),
                 )
             )
         ).all()

tests/domain/test_applications.py

@@ -206,7 +206,7 @@ def test_get_applications_pending_creation():
     portfolio1 = PortfolioFactory.create(state="COMPLETED")
     app_ready = ApplicationFactory.create(portfolio=portfolio1)
 
-    app_claimed = ApplicationFactory.create(portfolio=portfolio1, claimed_until=later)
+    app_done = ApplicationFactory.create(portfolio=portfolio1, cloud_id="123456")
 
     portfolio2 = PortfolioFactory.create(state="UNSTARTED")
     app_not_ready = ApplicationFactory.create(portfolio=portfolio2)