[bug]: TopoStats testing suite failing without apparent cause

[SylviaWhittle]

Checklist

• Run using the main branch to check if the issue persists. Instructions on how to do this can be found here.
• Find the offending file in the output. If processing halts, re-run analysis with topostats --core 1 process.
• Describe the bug.
• Include the configuration file.
• Copy of the log-file from running with topostats --log-level debug <command>.
• The exact command that failed. This is what you typed at the command line, including any options.
• TopoStats version, this is reported by topostats --version
• Operating System and Python Version

Describe the bug

No time to properly document. See #1376 and #1374 to see that the tests are failing at the same point on image comparisons in two PRs that do not mess with the underlying data.

Someone look into this please. Thanks.

Copy of the log-file from running with topostats --log-level debug <command>

NA

Include the configuration file

NA

To Reproduce

NA

TopoStats Version

Git main branch

Python Version

3.11

Operating System

MacOS M1/M2 (post-2021)

Python Packages

NA

[ubdbra001]

Likely culprit: A newer version of matplotlib - 3.11 was released on 11/06/26.

If this is the case then we can either pin the version or update the baseline images.
Updating the baseline images may affect whether the same tests pass on Python 3.10, as I think it uses the 3.10 version of matplotlib

Will continue testing.

[ubdbra001]

Cause confirmed as matplotlib v3.11.0

• Pinning to ~=3.10 fixes the issue for Python 3.10 and 3.11, but ties the software to an old dependency
• Updating images works for Python 3.11, but breaks tests for 3.10

[ns-rse]

Noting here as I was chatting with @ubdbra001 earlier and saw that the problem appears to be the default font has changed in maptlotlib-v3.11.0.

For reference, running the tests (locally) with the optoin --mpl-generate-summary=html produces a useful HTML output for comparing images that revealed the cause.