cloud-storage-mocker 0.2.1

Mocker library of Google Cloud Storage with local filesystem mounting.

cloud-storage-mocker

Mocker library of Google Cloud Storage Python client with local filesystem mounting.

Install

For package users:

pip install cloud-storage-mocker

For package developers:

git clone [e-mail]:odashi/cloud-storage-mocker
cd cloud-storage-mocker
python -m venv venv
source venv/bin/activate
pip install -e '.[dev]'

How the package works

This library provides patch context manager, which replaces following classes on the google-cloud-storage package:

• Client
• Bucket
• Blob

patch takes a list of Mount objects, which represent mappings between bucket names and directories on the local filesystem. Each Mount has Boolean configs readable and writable to control read/write permissions to the mounted buckets.

A canonical use-case of this package is writing unit tests to check the behavior of the code that works with Google Cloud Storage:

import pathlib

import google.cloud.storage  # type: ignore[import]

from cloud_storage_mocker import Mount
from cloud_storage_mocker import patch as gcs_patch


def test_something(tmp_path: pathlib.Path) -> None:
    # Creates two temporary directories for readable/writable buckets.
    src_dir = tmp_path / "src"
    dest_dir = tmp_path / "dest"
    src_dir.mkdir()
    dest_dir.mkdir()

    # A sample file on the readable bucket.
    (src_dir / "hello.txt").write_text("Hello.")

    # Mounts directories. Empty list is allowed if no actual access is required.
    with gcs_patch(
        [
            Mount("readable", src_dir, readable=True),
            Mount("writable", dest_dir, writable=True),
        ],
    ):
        client = google.cloud.storage.Client()

        # Reads a blob.
        blob = client.bucket("readable").blob("hello.txt")
        assert blob.download_as_text() == "Hello."

        # Writes a blob.
        blob = client.bucket("writable").blob("world.txt")
        blob.upload_from_string("World.")

    # Checks if the file is written appropriately.
    assert (dest_dir / "world.txt").read_text() == "World."

Patched methods

Methods listed below have specialized behavior to mount the local filesystem.

Other methods are mapped to MagicMock.

• Client()
• Client.bucket()
• Bucket()
• Bucket.blob()
• Blob()
• Blob.download_to_file()
• Blob.download_to_filename()
• Blob.download_as_bytes()
• Blob.download_as_string()
• Blob.download_as_text()
• Blob.upload_from_file()
• Blob.upload_from_filename()
• Blob.upload_from_string()

Caution

This library is basically provided for writing unit tests. DO NOT use this library on any code on the production.