Mock Azure Blob Upload and Download in Python

import io
import json
from datetime import datetime, timezone

class MockBlob:
    def __init__(self, name):
        self.name = name
        self.content = b""
        self.properties = {
            "last_modified": datetime.now(timezone.utc).isoformat(),
            "size": 0,
        }

    def upload(self, data, overwrite=False):
        if not overwrite and self.content:
            raise ValueError("Blob already exists; set overwrite=True")
        self.content = bytes(data)
        self.properties["size"] = len(self.content)
        self.properties["last_modified"] = datetime.now(timezone.utc).isoformat()

    def download(self):
        return io.BytesIO(self.content)

    def to_dict(self):
        return {
            "name": self.name,
            "size": self.properties["size"],
            "last_modified": self.properties["last_modified"],
        }

class MockBlobServiceClient:
    def __init__(self):
        self._blobs = {}

    def get_blob_client(self, container, blob_name):
        key = f"{container}/{blob_name}"
        if key not in self._blobs:
            blob = MockBlob(blob_name)
            blob._container = container
            self._blobs[key] = blob
        return self._blobs[key]

if __name__ == "__main__":
    service = MockBlobServiceClient()
    blob = service.get_blob_client("data", "sample.json")

    payload = {"task": "mock-azure", "count": 3}
    blob.upload(json.dumps(payload).encode("utf-8"), overwrite=True)

    downloaded = json.loads(blob.download().read().decode("utf-8"))
    print("Uploaded metadata:", blob.to_dict())
    print("Downloaded content:", downloaded)