domain repos for PE numbers and task orders

tests/domain/test_task_orders.py

@@ -0,0 +1,34 @@
+import pytest
+
+from atst.domain.exceptions import NotFoundError
+from atst.domain.task_orders import TaskOrders
+
+from tests.factories import TaskOrderFactory
+
+
+@pytest.fixture()
+def task_orders(db):
+    return TaskOrders(db)
+
+@pytest.fixture(scope="function")
+def new_task_order(db):
+    def make_task_order(**kwargs):
+        to = TaskOrderFactory.create(**kwargs)
+        db.add(to)
+        db.commit()
+
+        return to
+
+    return make_task_order
+
+
+def test_can_get_task_order(task_orders, new_task_order):
+    new_to = new_task_order(number="0101969F")
+    to = task_orders.get(new_to.number)
+
+    assert to.id == to.id
+
+
+def test_nonexistent_task_order_raises(task_orders):
+    with pytest.raises(NotFoundError):
+        task_orders.get("some fake number")