fix reading blob chars in text mode using StorageStreamDownloader.read()

[mlschodkowski]

Description

StorageStreamDownloader.read() on blob behaves differently when using chars vs size, but this should behave the same (according to documentation). This single change fixes discrepancies in number of chars read when specifying negative number in StorageStreamDownloader.read()

Example
download_blob().read(size=-1) behaves differently than download_blob(encoding='utf-8').read(chars=-1)

>>> upload("123456", ...)
>>> download_blob().read(size=-1)
# will return "123456" in bytes
>>> download_blob(encoding='utf-8').read(chars=-1)
"12345" # will return len(content) - 1 characters instead of full content

All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

General Guidelines and Best Practices

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[github-actions]

Thank you for your contribution @777moneymaker! We will review the pull request and get back to you soon.

[azure-sdk]

API change check

API changes are not detected in this pull request.

[jalauzon-msft]

Sorry for the delay, I have been away for the holiday season. Thanks for your contribution! This change looks good, but could you please apply the same change to our async implementation here:

azure-sdk-for-python/sdk/storage/azure-storage-blob/azure/storage/blob/aio/_download_async.py

Line 561 in cfa5ac8

size = chars if chars else sys.maxsize

This can be tested using our async clients. Once that's done, we can approve and merge his change, thanks.

[mlschodkowski]

Sorry for the delay, I have been away for the holiday season. Thanks for your contribution! This change looks good, but could you please apply the same change to our async implementation here:

azure-sdk-for-python/sdk/storage/azure-storage-blob/azure/storage/blob/aio/_download_async.py

Line 561 in cfa5ac8

size = chars if chars else sys.maxsize

This can be tested using our async clients. Once that's done, we can approve and merge his change, thanks.

Hey, no problem. The change has just been committed.

[mlschodkowski]

@microsoft-github-policy-service agree

[jalauzon-msft]

Hi @777moneymaker Leon, thanks again for your contribution! I have approved and merged this and it will be included in our next release.