Add ORM models for the simulation data

- add new ORM models `ReplaySimulation` and `ReplayedOrder`
  to store the data generated by the routing simulations
- add migrations script to create the corresponding database tables
  + create "replay_simulations" and "replayed_orders" tables
  + add missing check constraints to "orders" table
  + add unique constraint to "orders" table to enable compound key
  + drop unnecessary check constraints from the "orders" table
- add tests for the new ORM models
  + add `simulation`, `replayed_order`, `make_replay_order()`, and
    `pre_order` fixtures
  + add `ReplayedOrderFactor` faker class
- fix some typos

tests/db/fake_data/factories/orders/replayed.py

@@ -0,0 +1,120 @@
+"""Factory to create `Order` and `ReplayedOrder` instances."""
+
+import datetime as dt
+
+import factory
+from factory import alchemy
+
+from tests.db.fake_data.factories import utils
+from urban_meal_delivery import db
+
+
+class ReplayedOrderFactory(alchemy.SQLAlchemyModelFactory):
+    """Create instances of the `db.ReplayedOrder` model.
+
+    For simplicity, we assume the underlying `.order` to be an ad-hoc `Order`.
+    """
+
+    class Meta:
+        model = db.ReplayedOrder
+        sqlalchemy_get_or_create = ('simulation_id', 'order_id')
+
+    # Generic columns
+    # simulation -> set by the `make_replay_order` fixture for better control
+    # actual (`Order`) -> set by the `make_replay_order` fixture for better control
+
+    # `Order`-type related columns
+    ad_hoc = factory.LazyAttribute(lambda obj: obj.actual.ad_hoc)
+    placed_at = factory.LazyAttribute(lambda obj: obj.actual.placed_at)
+    scheduled_delivery_at = factory.LazyAttribute(
+        lambda obj: obj.actual.scheduled_delivery_at,
+    )
+    cancelled_at = None
+
+    # Restaurant-related columns
+    estimated_prep_duration = 1200
+    restaurant_notified_at = factory.LazyAttribute(
+        lambda obj: obj.placed_at
+        + utils.random_timespan(min_seconds=1, max_seconds=30),
+    )
+    restaurant_confirmed_at = factory.LazyAttribute(
+        lambda obj: obj.restaurant_notified_at
+        + utils.random_timespan(min_seconds=1, max_seconds=60),
+    )
+    restaurant_ready_at = factory.LazyAttribute(
+        lambda obj: obj.restaurant_confirmed_at
+        + dt.timedelta(seconds=obj.estimated_prep_duration)
+        + utils.random_timespan(min_seconds=300, max_seconds=300),
+    )
+
+    # Dispatch-related columns
+    dispatch_at = factory.LazyAttribute(
+        lambda obj: obj.actual.placed_at
+        + utils.random_timespan(min_seconds=30, max_seconds=60),
+    )
+    first_estimated_delivery_at = factory.LazyAttribute(
+        lambda obj: obj.restaurant_notified_at
+        + dt.timedelta(seconds=obj.estimated_prep_duration)
+        + dt.timedelta(minutes=10),
+    )
+    # courier -> set by the `make_replay_order` fixture for better control
+    courier_notified_at = factory.LazyAttribute(
+        lambda obj: obj.dispatch_at
+        + utils.random_timespan(min_seconds=1, max_seconds=30),
+    )
+    courier_accepted_at = factory.LazyAttribute(
+        lambda obj: obj.courier_notified_at
+        + utils.random_timespan(min_seconds=1, max_seconds=60),
+    )
+    utilization = None
+
+    # Pickup-related columns
+    reached_pickup_at = factory.LazyAttribute(
+        lambda obj: obj.restaurant_ready_at
+        + utils.random_timespan(min_seconds=1, max_seconds=60),
+    )
+    pickup_at = factory.LazyAttribute(
+        lambda obj: obj.reached_pickup_at
+        + utils.random_timespan(min_seconds=30, max_seconds=60),
+    )
+    left_pickup_at = factory.LazyAttribute(
+        lambda obj: obj.pickup_at
+        + utils.random_timespan(min_seconds=30, max_seconds=60),
+    )
+
+    # Delivery-related columns
+    reached_delivery_at = factory.LazyAttribute(
+        lambda obj: obj.left_pickup_at
+        + utils.random_timespan(min_minutes=5, max_minutes=10),
+    )
+    delivery_at = factory.LazyAttribute(
+        lambda obj: obj.reached_delivery_at
+        + utils.random_timespan(min_seconds=30, max_seconds=60),
+    )
+
+    @factory.post_generation
+    def post(obj, _create, _extracted, **_kwargs):  # noqa:B902,C901,N805
+        """Discard timestamps that occur after cancellation."""
+        if obj.cancelled_at:
+            if obj.cancelled_at <= obj.restaurant_notified_at:
+                obj.restaurant_notified_at = None
+            if obj.cancelled_at <= obj.restaurant_confirmed_at:
+                obj.restaurant_confirmed_at = None
+            if obj.cancelled_at <= obj.restaurant_ready_at:
+                obj.restaurant_ready_at = None
+            if obj.cancelled_at <= obj.dispatch_at:
+                obj.dispatch_at = None
+            if obj.cancelled_at <= obj.courier_notified_at:
+                obj.courier_notified_at = None
+            if obj.cancelled_at <= obj.courier_accepted_at:
+                obj.courier_accepted_at = None
+            if obj.cancelled_at <= obj.reached_pickup_at:
+                obj.reached_pickup_at = None
+            if obj.cancelled_at <= obj.pickup_at:
+                obj.pickup_at = None
+            if obj.cancelled_at <= obj.left_pickup_at:
+                obj.left_pickup_at = None
+            if obj.cancelled_at <= obj.reached_delivery_at:
+                obj.reached_delivery_at = None
+            if obj.cancelled_at <= obj.delivery_at:
+                obj.delivery_at = None