cloud-storage-mocker 0.0.1a5

Mocker library of Google Cloud Storage with local filesystem mounting.

cloud-storage-mocker

Mocker library of Google Cloud Storage 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 tempfile

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() -> None:
    # Creates two temporary directories, and mount them as readable/writable buckets.
    with (
        tempfile.TemporaryDirectory() as readable_dir,
        tempfile.TemporaryDirectory() as writable_dir,
        gcs_patch(
            [
                Mount("readable_bucket", readable_dir, readable=True),
                Mount("writable_bucket", writable_dir, writable=True),
            ]
        ),
    ):
        # Reads a blob.
        with open(readable_dir + "/test.txt", "w") as fp:
            fp.write("Hello.")
        blob = google.cloud.storage.Client().bucket("readable_bucket").blob("test.txt")
        assert blob.download_as_text() == "Hello."

        # Writes a blob.
        blob = google.cloud.storage.Client().bucket("writable_bucket").blob("test.txt")
        blob.upload_from_string("World.")
        with open(writable_dir + "/test.txt") as fp:
            assert fp.read() == "World."

Patched methods

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

Other methods are mapped to MagicMock.

• Client()
• Client.bucket()
• Bucket.blob()
• Blob.download_as_text()
• 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.