add PackageSource SQLAlchemy ORM model

Signed-off-by: Kevin Morris <kevr@0cost.org>

aurweb/models/package_source.py

+from sqlalchemy import Column, ForeignKey, Integer
+from sqlalchemy.exc import IntegrityError
+from sqlalchemy.orm import backref, relationship
+
+import aurweb.models.package
+
+from aurweb.models.declarative import Base
+
+
+class PackageSource(Base):
+    __tablename__ = "PackageSources"
+
+    PackageID = Column(Integer, ForeignKey("Packages.ID", ondelete="CASCADE"),
+                       nullable=False)
+    Package = relationship(
+        "Package", backref=backref("package_sources", lazy="dynamic"),
+        foreign_keys=[PackageID])
+
+    __mapper_args__ = {"primary_key": [PackageID]}
+
+    def __init__(self,
+                 Package: aurweb.models.package.Package = None,
+                 **kwargs):
+        super().__init__(**kwargs)
+
+        self.Package = Package
+        if not self.Package:
+            raise IntegrityError(
+                statement="Foreign key PackageID cannot be null.",
+                orig="PackageSources.PackageID",
+                params=("NULL"))

test/test_package_source.py

+import pytest
+
+from sqlalchemy.exc import IntegrityError
+
+from aurweb.db import create, query, rollback
+from aurweb.models.account_type import AccountType
+from aurweb.models.package import Package
+from aurweb.models.package_base import PackageBase
+from aurweb.models.package_source import PackageSource
+from aurweb.models.user import User
+from aurweb.testing import setup_test_db
+
+user = pkgbase = package = None
+
+
+@pytest.fixture(autouse=True)
+def setup():
+    global user, pkgbase, package
+
+    setup_test_db("PackageSources", "Packages", "PackageBases", "Users")
+
+    account_type = query(AccountType,
+                         AccountType.AccountType == "User").first()
+    user = create(User, Username="test", Email="test@example.org",
+                  RealName="Test User", Passwd="testPassword",
+                  AccountType=account_type)
+    pkgbase = create(PackageBase,
+                     Name="test-package",
+                     Maintainer=user)
+    package = create(Package, PackageBase=pkgbase, Name="test-package")
+
+
+def test_package_source():
+    pkgsource = create(PackageSource, Package=package)
+    assert pkgsource.Package == package
+    # By default, PackageSources.Source assigns the string '/dev/null'.
+    assert pkgsource.Source == "/dev/null"
+    assert pkgsource.SourceArch is None
+
+
+def test_package_source_null_package_raises_exception():
+    with pytest.raises(IntegrityError):
+        create(PackageSource)
+    rollback()