Mock GCP storage bucket blob upload in Python

import io
from datetime import datetime
from unittest.mock import MagicMock, patch


class MockBlob:
    """Simulates a GCP storage blob for unit testing."""
    def __init__(self, name):
        self.name = name
        self.uploaded_at = None
        self.content = b""

    def upload_from_file(self, file_obj):
        self.content = file_obj.read()
        self.uploaded_at = datetime.utcnow().isoformat()

    def download_as_string(self):
        return self.content

    def __repr__(self):
        return f"MockBlob(name='{self.name}', size={len(self.content)}, uploaded_at={self.uploaded_at})"


class MockBucket:
    """Simulates a GCP storage bucket."""
    def __init__(self, name):
        self.name = name
        self.blobs = {}

    def blob(self, blob_name):
        if blob_name not in self.blobs:
            self.blobs[blob_name] = MockBlob(blob_name)
        return self.blobs[blob_name]

    def list_blobs(self):
        return list(self.blobs.values())


class MockStorageClient:
    """Simulates the GCP storage client."""
    def __init__(self):
        self.buckets = {}

    def bucket(self, bucket_name):
        if bucket_name not in self.buckets:
            self.buckets[bucket_name] = MockBucket(bucket_name)
        return self.buckets[bucket_name]


def upload_blob(client, bucket_name, blob_name, data: bytes):
    """Upload data as a blob to a mock GCP storage bucket."""
    bucket = client.bucket(bucket_name)
    blob = bucket.blob(blob_name)
    blob.upload_from_file(io.BytesIO(data))
    return blob


if __name__ == "__main__":
    client = MockStorageClient()
    blob = upload_blob(client, "my-bucket", "folder/hello.txt", b"Hello GCP!")
    print(blob)
    print("Downloaded:", blob.download_as_string().decode())
    print("Uploaded at:", blob.uploaded_at)