Support TAS58xx 'volume' capability for ALSA volume control

[balloob]

Summary

• Detect volume (not just pvolume) in ALSA mixer capabilities, fixing hardware volume control for TAS58xx-based DAC HATs like the Sonocotta Louder Raspberry
• Add parametrized tests covering mono (volume volume-joined) and stereo (volume) modes, plus discovery and get_volume flows
• Fix test portability by monkeypatching AVAILABLE so discovery tests pass on non-Linux CI

Based on the work in #214 by @chaudis, with simplified tests.

Closes #214

Test plan

• test_find_mixer_element_tas58xx[mono] — detects volume volume-joined
• test_find_mixer_element_tas58xx[stereo] — detects volume
• test_louder_raspberry_discovery — full device→card→element flow
• test_louder_raspberry_get_volume — reads back correct volume percentage

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Updates ALSA mixer discovery to support TAS58xx-based DAC/amplifier HATs whose amixer sget output reports volume (and volume-joined) instead of pvolume, and extends the test suite to cover these cases and end-to-end discovery/get-volume flows.

Changes:

• Extend _has_playback_volume() to treat volume as a valid playback-volume capability alongside pvolume.
• Update ALSA volume discovery docs/comments to reflect the expanded capability handling.
• Add TAS58xx/Sonocotta Louder Raspberry test cases (mono + stereo capability detection, discovery flow, get_state parsing).

Reviewed changes

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

File	Description
sendspin/alsa_volume.py	Accept volume capability during mixer-element capability checks and update related docs/comments.
tests/test_alsa_volume.py	Add TAS58xx-focused capability/discovery/get-volume tests.

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[Copilot]

import pytest is placed mid-file (after many test definitions). Ruff's E402/I001 rules typically require imports to be at the top of the module; this will likely fail linting. Move the pytest import into the main import block at the top of the file.

[Copilot]

The parametrized test takes desc but never uses it, and the docstring contains {desc} without being an f-string. With Ruff enabled, this is likely to trigger an unused-argument lint error. Either drop the desc parameter (the parametrization ids already cover readability) or reference it in the test so it’s actually used.

Suggested change

	("digital_output", "desc"),
	[
	(_TAS58XX_SGET_DIGITAL_MONO, "mono (volume volume-joined)"),
	(_TAS58XX_SGET_DIGITAL_STEREO, "stereo (volume)"),
	],
	ids=["mono", "stereo"],
	)
	def test_find_mixer_element_tas58xx(monkeypatch, digital_output: str, desc: str) -> None:
	"""TAS58xx 'volume' capability is detected — {desc}."""
	"digital_output",
	[
	_TAS58XX_SGET_DIGITAL_MONO,
	_TAS58XX_SGET_DIGITAL_STEREO,
	],
	ids=["mono", "stereo"],
	)
	def test_find_mixer_element_tas58xx(monkeypatch, digital_output: str) -> None:
	"""TAS58xx 'volume' capability is detected."""

[Copilot]

This test monkeypatches _alsa_mod.AVAILABLE = True to make the discovery path runnable off-Linux. However, other tests in this module also call async_check_alsa_available(...) expecting a non-None result and don’t patch AVAILABLE, so the suite can still fail on non-Linux CI. Consider a shared fixture (or module-level setup) that forces AVAILABLE=True for all tests that exercise ALSA discovery logic.

[Copilot]

pvolume_elements now collects elements with either pvolume or volume capability, so the name is misleading. Renaming it (and related variables like selected) to something like volume_elements would better reflect the broadened behavior and reduce future confusion.