[FastAPI] Refactor db modifications

For SQLAlchemy to automatically understand updates from the
external world, it must use an `autocommit=True` in its session.

This change breaks how we were using commit previously, as
`autocommit=True` causes SQLAlchemy to commit when a
SessionTransaction context hits __exit__.

So, a refactoring was required of our tests: All usage of
any `db.{create,delete}` must be called **within** a
SessionTransaction context, created via new `db.begin()`.

From this point forward, we're going to require:

```
with db.begin():
    db.create(...)
    db.delete(...)
    db.session.delete(object)
```

With this, we now get external DB modifications automatically
without reloading or restarting the FastAPI server, which we
absolutely need for production.

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

test/test_package_dependency.py

@@ -2,7 +2,8 @@ import pytest
 
 from sqlalchemy.exc import IntegrityError
 
-from aurweb.db import commit, create, query
+from aurweb import db
+from aurweb.db import create, query
 from aurweb.models.account_type import AccountType
 from aurweb.models.dependency_type import DependencyType
 from aurweb.models.package import Package
@@ -22,25 +23,28 @@ def setup():
 
     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=pkgbase.Name,
-                     Description="Test description.",
-                     URL="https://test.package")
+    with db.begin():
+        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=pkgbase.Name,
+                         Description="Test description.",
+                         URL="https://test.package")
 
 
 def test_package_dependencies():
     depends = query(DependencyType, DependencyType.Name == "depends").first()
-    pkgdep = create(PackageDependency, Package=package,
-                    DependencyType=depends,
-                    DepName="test-dep")
+
+    with db.begin():
+        pkgdep = create(PackageDependency, Package=package,
+                        DependencyType=depends,
+                        DepName="test-dep")
     assert pkgdep.DepName == "test-dep"
     assert pkgdep.Package == package
     assert pkgdep.DependencyType == depends
@@ -49,8 +53,8 @@ def test_package_dependencies():
 
     makedepends = query(DependencyType,
                         DependencyType.Name == "makedepends").first()
-    pkgdep.DependencyType = makedepends
-    commit()
+    with db.begin():
+        pkgdep.DependencyType = makedepends
     assert pkgdep.DepName == "test-dep"
     assert pkgdep.Package == package
     assert pkgdep.DependencyType == makedepends
@@ -59,8 +63,8 @@ def test_package_dependencies():
 
     checkdepends = query(DependencyType,
                          DependencyType.Name == "checkdepends").first()
-    pkgdep.DependencyType = checkdepends
-    commit()
+    with db.begin():
+        pkgdep.DependencyType = checkdepends
     assert pkgdep.DepName == "test-dep"
     assert pkgdep.Package == package
     assert pkgdep.DependencyType == checkdepends
@@ -69,8 +73,8 @@ def test_package_dependencies():
 
     optdepends = query(DependencyType,
                        DependencyType.Name == "optdepends").first()
-    pkgdep.DependencyType = optdepends
-    commit()
+    with db.begin():
+        pkgdep.DependencyType = optdepends
     assert pkgdep.DepName == "test-dep"
     assert pkgdep.Package == package
     assert pkgdep.DependencyType == optdepends
@@ -79,39 +83,37 @@ def test_package_dependencies():
 
     assert not pkgdep.is_package()
 
-    base = create(PackageBase, Name=pkgdep.DepName, Maintainer=user)
-    create(Package, PackageBase=base, Name=pkgdep.DepName)
+    with db.begin():
+        base = create(PackageBase, Name=pkgdep.DepName, Maintainer=user)
+        create(Package, PackageBase=base, Name=pkgdep.DepName)
 
     assert pkgdep.is_package()
 
 
 def test_package_dependencies_null_package_raises_exception():
-    from aurweb.db import session
-
     depends = query(DependencyType, DependencyType.Name == "depends").first()
     with pytest.raises(IntegrityError):
-        create(PackageDependency,
-               DependencyType=depends,
-               DepName="test-dep")
-    session.rollback()
+        with db.begin():
+            create(PackageDependency,
+                   DependencyType=depends,
+                   DepName="test-dep")
+    db.rollback()
 
 
 def test_package_dependencies_null_dependency_type_raises_exception():
-    from aurweb.db import session
-
     with pytest.raises(IntegrityError):
-        create(PackageDependency,
-               Package=package,
-               DepName="test-dep")
-    session.rollback()
+        with db.begin():
+            create(PackageDependency,
+                   Package=package,
+                   DepName="test-dep")
+    db.rollback()
 
 
 def test_package_dependencies_null_depname_raises_exception():
-    from aurweb.db import session
-
     depends = query(DependencyType, DependencyType.Name == "depends").first()
     with pytest.raises(IntegrityError):
-        create(PackageDependency,
-               Package=package,
-               DependencyType=depends)
-    session.rollback()
+        with db.begin():
+            create(PackageDependency,
+                   Package=package,
+                   DependencyType=depends)
+    db.rollback()