Add focused pytest coverage for display and LVGL metadata validation

[Copilot]

This adds targeted pytest coverage for the display metadata / LVGL metadata-validation refactor on lvgl-endian. The new tests lock in the ID-resolution guard behavior in display and the byte-order validation/fallback contract in lvgl.final_validation().

• Display metadata guard coverage

  • Add assertions for metadata access before ID resolution completes.
  • Cover both get_display_metadata() and get_all_display_metadata() using real ID objects with unresolved id=None.

• Duplicate registration coverage

  • Add a focused test proving add_metadata() rejects duplicate registration of the same ID object.

• LVGL byte-order validation coverage

  • Add/retain coverage for a single LVGL instance configured with multiple displays that advertise conflicting byte_order metadata.
  • Verify LVGL rejects mixed display byte orders with a clear validation failure.

• LVGL default fallback coverage

  • Add/retain coverage for the no-override path where LVGL config omits byte_order and display metadata does not supply one.
  • Verify final validation defaults LVGL to big_endian.

• Test fixtures kept narrow

  • Use minimal resolved-ID config structures for LVGL validation tests rather than broader integration setup.
  • Keep coverage concentrated in existing component test modules under tests/component_tests/display/ and tests/component_tests/lvgl/.

Example of the guarded metadata contract covered by these tests:

display_id = ID(None)
add_metadata(display_id, 320, 240)

with pytest.raises(AssertionError, match="resolved"):
    get_display_metadata("display_1")

Original prompt

Add focused pytest coverage on branch lvgl-endian in repository clydebarrow/esphome to address remaining test gaps in the display metadata / LVGL metadata-validation refactor.

Context:

• The branch head includes commit 3edb476c2d6f3501ec34047b7c4aeae24f9de004 ([lvgl][mipi_spi][mipi_rgb][mipi_dsi] Metadata validation).
• esphome/components/display/__init__.py now stores metadata as a list of (ID, DisplayMetaData) tuples and explicitly guards against metadata lookups before IDs have been resolved.
• esphome/components/lvgl/__init__.py performs final validation using display metadata for byte_order, has_writer, rotation, and draw_rounding.
• mipi_spi, mipi_rgb, and mipi_dsi all populate the expanded metadata fields.

Please create a pull request against branch lvgl-endian that adds pytest cases for the missing/high-value coverage areas below.

Required tests to add:

1. Display metadata guard tests

• Add tests for the new assertion guards in esphome/components/display/__init__.py:
  • get_display_metadata() should assert if metadata contains an unresolved ID (i.e. id_.id is None).
  • get_all_display_metadata() should assert if any stored metadata entry has an unresolved ID.
• Use realistic ID objects rather than string stand-ins.

2. Duplicate metadata registration test

• Add a test ensuring add_metadata() rejects duplicate registration for the same ID object.
• Assert on the failure/exception behavior introduced by the new duplicate check.

3. LVGL cross-display byte-order validation test

• Add a test that verifies lvgl.final_validation() rejects a single LVGL instance configured with multiple displays whose metadata advertises different byte_order values.
• Prefer a focused unit/component test that directly exercises final validation with realistic config structures and resolved IDs, rather than a broad integration test if that is simpler and more stable.

4. LVGL default byte-order fallback test

• Add a test ensuring that when LVGL config omits byte_order and no display metadata contributes an override, final validation defaults LVGL to big_endian.
• Keep the test narrowly scoped and deterministic.

Implementation guidance:

• Keep the new tests minimal and consistent with the existing test style in this repository.
• Reuse or extend existing test modules if appropriate (for example under tests/component_tests/display/ and tests/component_tests/lvgl/).
• Avoid changing production code unless strictly required to make the tests meaningful.
• If any existing tests are stale because of the ID-based metadata API change, update them as needed as part of the PR so the suite reflects the current behavior.

Success criteria:

• New tests fail on the pre-change behavior and pass with the current refactor.
• Tests clearly validate the intended metadata contract and LVGL final-validation behavior.
• PR includes only test changes or the smallest necessary supporting test adjustments.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: Review the changes just pushed to branch lvgl-endian

Assistant: The latest push on lvgl-endian looks reviewable but not merge-ready as-is because the branch also contains a very large unrelated drift from dev. The most recent commit itself is focused and reasonable; the branch overall is not.

PR Summary

There doesn’t appear to be an open PR for clydebarrow:lvgl-endian, so I reviewed the latest pushed commit plus the branch diff against the repo’s default branch dev.

• Repo default branch: dev
• Branch head commit: 3edb476c2d6f3501ec34047b7c4aeae24f9de004
• Latest commit title: [lvgl][mipi_spi][mipi_rgb][mipi_dsi] Metadata validation
• Latest commit stats: 7 files changed, +423 / -127 overall, but only 6 source/test files are directly tied to the LVGL/display metadata change; the rest of branch diff contains lots of unrelated upstream changes.
• Open PR found: none
• Risk:
  • Latest commit only: low-to-medium
  • Whole branch vs dev: high, because it includes a huge amount of unrelated change

Core Changes

The latest commit introduces a cleaner display metadata contract so LVGL can validate compatibility using metadata rather than peeking into raw display config structures.

What changed in the latest commit

1. display metadata expanded
   • DisplayMetaData now includes:
     • byte_order
     • rotation
     • draw_rounding
     • has_writer
     • has_hardware_rotation
2. Metadata registration moved earlier
   • mipi_spi, mipi_rgb, and mipi_dsi now call display.add_metadata(...) during schema/config processing rather than later codegen paths.
3. LVGL final validation now uses metadata
   • It:
     • auto-infers byte_order from attached displays
     • rejects mixed display byte orders in one LVGL instance
     • rejects displays marked...

This pull request was created from Copilot chat.