SqliteZipStorage: Ensure the filepath is absolute and exists

Otherwise, loading the storage will fail as soon as the working
directory is changed.

aiida/storage/sqlite_zip/backend.py

@@ -21,7 +21,7 @@
 from zipfile import ZipFile, is_zipfile
 
 from archive_path import ZipPath, extract_file_in_zip
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
 from sqlalchemy.orm import Session
 
 from aiida import __version__
@@ -66,12 +66,21 @@ class SqliteZipBackend(StorageBackend):  # pylint: disable=too-many-public-metho
     """
 
     class Configuration(BaseModel):
+        """Model describing required information to configure an instance of the storage."""
 
         filepath: str = Field(
             title='Filepath of the archive',
             description='Filepath of the archive in which to store data for this backend.'
         )
 
+        @field_validator('filepath')
+        @classmethod
+        def filepath_exists_and_is_absolute(cls, value: str) -> str:
+            """Validate the filepath exists and return the resolved and absolute filepath."""
+            filepath = Path(value)
+            assert filepath.is_file(), f'The archive `{value}` does not exist.'
+            return str(filepath.resolve().absolute())
+
     _read_only = True
 
     @classmethod

tests/storage/sqlite_zip/__init__.py

@@ -0,0 +1,2 @@
+# -*- coding: utf-8 -*-
+"""Tests for :mod:`aiida.storage.sqlite_zip`."""

tests/storage/sqlite_zip/test_backend.py

@@ -1,5 +1,10 @@
 # -*- coding: utf-8 -*-
-"""Tests for :mod:`aiida.storage.sqlite_zip.backend.SqliteZipBackend`."""
+"""Tests for :mod:`aiida.storage.sqlite_zip.backend`."""
+import pathlib
+
+from pydantic_core import ValidationError
+import pytest
+
 from aiida.storage.sqlite_zip.backend import SqliteZipBackend
 from aiida.storage.sqlite_zip.migrator import validate_storage
 
@@ -45,3 +50,16 @@ def test_initialise_reset_false(tmp_path, aiida_caplog):
     assert filepath_archive.exists()
     validate_storage(filepath_archive)
     assert any('Migrating existing SqliteZipBackend' in record.message for record in aiida_caplog.records)
+
+
+@pytest.mark.usefixtures('chdir_tmp_path')
+def test_configuration():
+    """Test :class:`aiida.storage.sqlite_zip.backend.SqliteZipBackend.Configuration`."""
+    with pytest.raises(ValidationError, match=r'.*The archive `non-existent` does not exist.*'):
+        SqliteZipBackend.Configuration(filepath='non-existent')
+
+    filepath = pathlib.Path.cwd() / 'archive.aiida'
+    filepath.touch()
+
+    configuration = SqliteZipBackend.Configuration(filepath=filepath.name)
+    assert pathlib.Path(configuration.filepath).is_absolute()