Expand UnitOfWork and introduce SqlalchemyUnitOfWork, handling transactions; update inspect_bin test to use UnitOfWork

Author: ssciolla

dor/service_layer/unit_of_work.py

@@ -1,12 +1,91 @@
+from abc import ABC, abstractmethod
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+from dor.adapters.catalog import MemoryCatalog, SqlalchemyCatalog, _custom_json_serializer
+from dor.config import config
 from dor.domain.events import Event
 from gateway.repository_gateway import RepositoryGateway
 
 
-class UnitOfWork:
+class AbstractUnitOfWork(ABC):
+
+    @abstractmethod
+    def __enter__(self):
+        raise NotImplementedError
+
+    @abstractmethod
+    def __exit__(self, *args):
+        raise NotImplementedError
+
+    @abstractmethod
+    def commit(self) -> None:
+        raise NotImplementedError
+
+    @abstractmethod
+    def rollback(self) -> None:
+        raise NotImplementedError
+
+    def add_event(self, event: Event):
+        raise NotImplementedError
+
+    def pop_event(self) -> Event | None:
+        raise NotImplementedError
+
+
+class UnitOfWork(AbstractUnitOfWork):
 
     def __init__(self, gateway: RepositoryGateway) -> None:
         self.gateway = gateway
         self.events: list[Event] = []
+        self.catalog = MemoryCatalog()
+
+    def __enter__(self):
+        pass
+
+    def __exit__(self, *args):
+        self.rollback()
+
+    def commit(self):
+        self.committed = True
+
+    def rollback(self):
+        pass
+
+    def add_event(self, event: Event):
+        self.events.append(event)
+
+    def pop_event(self) -> Event | None:
+        if len(self.events) > 0:
+            return self.events.pop(0)
+        return None
+
+
+DEFAULT_SESSION_FACTORY = sessionmaker(bind=create_engine(
+    config.get_database_engine_url(), json_serializer=_custom_json_serializer
+))
+
+class SqlalchemyUnitOfWork(AbstractUnitOfWork):
+
+    def __init__(self, gateway: RepositoryGateway, session_factory=DEFAULT_SESSION_FACTORY) -> None:
+        self.session_factory = session_factory
+        self.gateway: RepositoryGateway = gateway
+        self.events: list[Event] = []
+
+    def __enter__(self):
+        self.session = self.session_factory()
+        self.catalog = SqlalchemyCatalog(self.session)
+
+    def __exit__(self, *args):
+        self.rollback()
+        self.session.close()
+
+    def commit(self):
+        self.session.commit()
+
+    def rollback(self):
+        self.session.rollback()
 
     def add_event(self, event: Event):
         self.events.append(event)

features/steps/inspect_bin.py

@@ -1,15 +1,21 @@
 from behave import given, then, when
 import uuid
 from datetime import datetime, UTC
+
 from pydantic_core import to_jsonable_python
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
 
-from dor.adapters.catalog import MemoryCatalog
+from dor.adapters.catalog import Base, _custom_json_serializer
+from dor.config import config
 from dor.domain.models import Bin
 from dor.service_layer import catalog_service
+from dor.service_layer.unit_of_work import SqlalchemyUnitOfWork, UnitOfWork
 from dor.providers.models import (
     Agent, AlternateIdentifier, FileMetadata, FileReference, PackageResource,
     PreservationEvent, StructMap, StructMapItem, StructMapType
 )
+from gateway.fake_repository_gateway import FakeRepositoryGateway
 
 
 @given(u'a preserved monograph with an alternate identifier of "{alt_id}"')
@@ -174,13 +180,24 @@ def step_impl(context, alt_id):
             )
         ]
     )
-    context.catalog = MemoryCatalog()
-    context.catalog.add(bin)
+
+    engine = create_engine(
+        config.get_test_database_engine_url(), json_serializer=_custom_json_serializer
+    )
+    session_factory = sessionmaker(bind=engine)
+    Base.metadata.drop_all(engine)
+    Base.metadata.create_all(engine)
+
+    context.uow = SqlalchemyUnitOfWork(gateway=FakeRepositoryGateway(), session_factory=session_factory)
+    with context.uow:
+        context.uow.catalog.add(bin)
+        context.uow.commit()
 
 @when(u'the Collection Manager looks up the bin by "{alt_id}"')
 def step_impl(context, alt_id):
     context.alt_id = alt_id
-    context.bin = context.catalog.get_by_alternate_identifier(alt_id)
+    with context.uow:
+        context.bin = context.uow.catalog.get_by_alternate_identifier(alt_id)
     context.summary = catalog_service.summarize(context.bin)
 
 @then(u'the Collection Manager sees the summary of the bin')
@@ -203,7 +220,8 @@ def step_impl(context):
 
 @when(u'the Collection Manager lists the contents of the bin for "{alt_id}"')
 def step_impl(context, alt_id):
-    context.bin = context.catalog.get_by_alternate_identifier(alt_id)
+    with context.uow:
+        context.bin = context.uow.catalog.get_by_alternate_identifier(alt_id)
     context.file_sets = catalog_service.get_file_sets(context.bin)
 
 @then(u'the Collection Manager sees the file sets.')

tests/test_unit_of_work.py

@@ -0,0 +1,50 @@
+from gateway.fake_repository_gateway import FakeRepositoryGateway
+import pytest
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+from dor.adapters.catalog import SqlalchemyCatalog, Base, _custom_json_serializer
+from dor.config import config
+from dor.service_layer.unit_of_work import SqlalchemyUnitOfWork
+
+
+def setup_function() -> None:
+    engine = create_engine(config.get_test_database_engine_url())
+    Base.metadata.drop_all(engine)
+    Base.metadata.create_all(engine)
+
+
+@pytest.fixture
+def session_factory():
+    return sessionmaker(bind=create_engine(
+        config.get_test_database_engine_url(), json_serializer=_custom_json_serializer
+    ))
+
+
+@pytest.mark.usefixtures("sample_bin")
+def test_uow_can_add_bin(session_factory, sample_bin):
+    gateway = FakeRepositoryGateway()
+    uow = SqlalchemyUnitOfWork(gateway=gateway, session_factory=session_factory)
+    with uow:
+        uow.catalog.add(sample_bin)
+        uow.commit()
+    
+    session = session_factory()
+    with session:
+        catalog = SqlalchemyCatalog(session)
+        bin = catalog.get(sample_bin.identifier)
+    assert bin == sample_bin
+
+
+@pytest.mark.usefixtures("sample_bin")
+def test_uow_does_not_add_bin_without_commit(session_factory, sample_bin):
+    gateway = FakeRepositoryGateway()
+    uow = SqlalchemyUnitOfWork(gateway=gateway, session_factory=session_factory)
+    with uow:
+        uow.catalog.add(sample_bin)
+    
+    session = session_factory()
+    with session:
+        catalog = SqlalchemyCatalog(session)
+        bin = catalog.get(sample_bin.identifier)
+    assert bin is None