fix: configure() no longer overwrites config set by configure_*() sub-methods

[mayuriphad]

Summary

Fixes #3841.

configure() unconditionally replaced the whole config object:

def configure(self, *args, **kwargs) -> Self:
    copy = self.copy(deep=False)
    copy.config = core.Config(*args, **kwargs)
    return copy

So calling it after any configure_*() sub-method (configure_axisBottom(), configure_view(), etc.) silently discarded everything the sub-method had set, e.g.:

chart = (
    alt.Chart(data)
    .mark_circle()
    .encode(x="foo", y="bar")
    .configure_axisBottom(orient="top")  # discarded by the next call
    .configure(tooltipFormat={"numberFormat": ".2f"})
)

The configure_*() sub-methods already merge into the existing config (copy.config["{prop}"] = ...), so configure() was the odd one out.

Fix

Updated the CONFIG_METHOD template in tools/generate_schema_wrapper.py (this generates ConfigMethodMixin.configure in altair/vegalite/v6/schema/mixins.py) so configure() merges its kwargs into the existing config instead of replacing it outright — same-key values still get overridden as expected, but unrelated keys set by earlier calls survive. Ran uv run python tools/generate_schema_wrapper.py to regenerate mixins.py from the updated template (the only functional change in the regenerated file is this method; unrelated dataset/theme metadata files that also get touched by the generator were left untouched).

Testing

• Added test_configure_merges_with_configure_prop_methods in tests/vegalite/v6/test_api.py, covering both the reported case (config set by configure_axisBottom() survives a later configure() call) and that configure() still overrides a key it set previously.
• uv run pytest tests/ -k config -q — 14 passed.
• Manually reproduced the exact repro from Bug: chart configure_axisBottom() has no effect if configure() is called later #3841 before the fix (bug confirmed) and after (fixed).

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.