Add tests for theme/aesthetic helper functions

[utkarshpawade]

Fixes #523

• Added legend_move("none") equivalence with legend_none()

[Copilot]

Pull request overview

Adds expanded test coverage for bayesplot theme/aesthetic convenience helpers, with checks for return types and compatibility when added to real bayesplot ggplot objects.

Changes:

• Added tests asserting helper outputs are incomplete themes and map on = FALSE to element_blank().
• Added composition tests ensuring helpers and overlay_function() can be added to real bayesplot plots.
• Added a NEWS entry documenting the added tests.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
tests/testthat/test-convenience-functions.R	Adds new testthat cases around theme helper return types and plot composition.
NEWS.md	Documents newly added tests for theme/aesthetic helpers.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.18%. Comparing base (6d49142) to head (6f82364).
⚠️ Report is 14 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #524   +/-   ##
=======================================
  Coverage   99.18%   99.18%           
=======================================
  Files          35       35           
  Lines        6120     6120           
=======================================
  Hits         6070     6070           
  Misses         50       50           

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[jgabry]

Thanks @utkarshpawade. I think the legend_move("none") test is worth keeping, since that behavior is explicitly documented and it guards a real contract of the helper.

For the rest, I’m not convinced the added tests are giving us much benefit. Most of these helpers are very thin wrappers around ggplot2::theme() or ggplot2::stat_function(), and the existing tests already cover the main behavior by checking the returned objects directly. The new composition tests mostly confirm that ggplot can still add a valid theme/layer object to a plot, which is more ggplot behavior than bayesplot behavior. The extra on = FALSE checks also seem redundant with the existing expectations that already compare against element_blank() themes.

So my preference would be to keep the legend_move("none") test and drop the others, to avoid adding test volume without much additional protection.

[jgabry]

Thanks, looks good! I'm looking into the failing CI run. It's not related to this PR, but I might try to fix it before merging more PRs.