[SYNPY-1553] Removes Blank Auth Header

[BWMac]

Problem:

In the Synapse Python Client users should be able to start an Anonymous session like:

import synapseclient

syn = synapseclient.Synapse()
syn.login(authToken="")

However, httpx does not automatically handle cases where an empty authentication token is provided. So, currently users will be met with an error like:

httpx.LocalProtocolError: Illegal header value b'Bearer '

when they attempt to start an Anonymous session.

Solution:

To fix this, need to not add the Authentication header to our request if the user has not provided a Synapse Authentication Token when using syn.login().

We also want to catch cases like these and inform users what they should do next after attempting to get an entity without having provided an authentication token.

Testing:

I added a unit test to cover the new warning message in _check_entity_restrictions and made some small changes to other tests to accommodate this update.

Note: warnings.warn is deprecated in Python 3.13. I updated _check_entity_restrictions to use logger.warning instead of .warn

[BryanFauble]

LGTM! Thanks

[Copilot]

Pull Request Overview

This PR addresses a bug where an empty authentication token causes an error by removing the blank Authorization header and by providing a clearer warning message for users. Key changes include:

• Adjusting the behavior of SynapseAuthTokenCredentials to skip adding a header when the token is empty.
• Refactoring _check_entity_restrictions in both client.py and entity_factory.py to use logger.warning instead of warnings.warn.
• Updating tests to accommodate and verify the new warning messages.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
tests/unit/synapseclient/unit_test_client.py	Updated tests to use instance variables and, in most cases, patched logger.warning; one test still patches warnings.warn.
synapseclient/core/credentials/cred_data.py	Added a condition to skip updating headers if the authentication token is empty.
synapseclient/client.py	Reworked _check_entity_restrictions to conditionally build a warning message and use logger.warning.
synapseclient/api/entity_factory.py	Updated _check_entity_restrictions to use logger.warning and align warning message logic with the client module.

Comments suppressed due to low confidence (1)

tests/unit/synapseclient/unit_test_client.py:1167

• The test still patches warnings.warn, but the updated implementation uses logger.warning. Update the patch target to 'logging.Logger.warning' so that the test properly captures the warning logs.

with patch("warnings.warn") as mocked_warn: