ci: add deployment workflow and automated tests

tests/fakes.py

@@ -0,0 +1,48 @@
+from sqlalchemy.exc import SQLAlchemyError
+
+from models import Todo
+
+
+class FakeScalarResult:
+    def __init__(self, todos: list[Todo]) -> None:
+        self.todos = todos
+
+    def all(self) -> list[Todo]:
+        return self.todos
+
+class FakeSession:
+    def __init__(self) -> None:
+        self.todo_to_return: Todo | None = None
+        self.added_todo: Todo | None = None
+        self.committed = False
+        self.deleted_todo: Todo | None = None
+        self.should_fail_commit = False
+        self.rolled_back = False
+        self.todos_to_return: list[Todo] = []
+
+    def add(self, todo: Todo) -> None:
+        self.added_todo = todo
+        todo.id = 1
+        todo.completion = False
+
+    def commit(self) -> None:
+        if self.should_fail_commit:
+            raise SQLAlchemyError("simulated commit failure")
+
+        self.committed = True
+
+    def get(
+        self,
+        _model: type[Todo],
+        _todo_id: int,
+    ) -> Todo | None:
+        return self.todo_to_return
+
+    def delete(self, todo: Todo) -> None:
+        self.deleted_todo = todo
+
+    def rollback(self) -> None:
+        self.rolled_back = True
+
+    def scalars(self, _statement: object) -> FakeScalarResult:
+        return FakeScalarResult(self.todos_to_return)