player/controls.py

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+"""Control-panel state: the data shape read from the Arduino over serial.
+
+This is the serial-contract payload shared with sub-project 4 (firmware). It
+models the full panel from design §6/§7: the 7-way content dial, the four
+experience knobs (0..4), and the two intensity levels (volume, brightness).
+The wire framing itself is the separate 3<->4 serial contract; this module is
+the *decoded* form.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, fields
+
+# The seven positions of the content dial (design §6).
+CONTENT_POSITIONS = frozenset(
+    {"off", "white_noise", "music", "audio_track", "video", "music_video", "audio_video"}
+)
+
+KNOB_FIELDS = ("left", "right", "dark", "light", "volume", "brightness")
+KNOB_MIN = 0
+KNOB_MAX = 4
+
+
+class ControlsError(ValueError):
+    """Raised when a Controls payload is structurally invalid."""
+
+
+@dataclass(frozen=True)
+class Controls:
+    content: str
+    left: int
+    right: int
+    dark: int
+    light: int
+    volume: int
+    brightness: int
+
+
+def validate_controls(c: Controls) -> None:
+    """Raise ControlsError if the payload is structurally invalid."""
+    if c.content not in CONTENT_POSITIONS:
+        raise ControlsError(
+            f"invalid content position {c.content!r}; "
+            f"expected one of {sorted(CONTENT_POSITIONS)}"
+        )
+    for name in KNOB_FIELDS:
+        value = getattr(c, name)
+        if isinstance(value, bool) or not isinstance(value, int):
+            raise ControlsError(f"knob {name} must be an int, got {value!r}")
+        if not (KNOB_MIN <= value <= KNOB_MAX):
+            raise ControlsError(
+                f"knob {name}={value} out of range {KNOB_MIN}..{KNOB_MAX}"
+            )
+
+
+def parse_controls(data: dict) -> Controls:
+    """Build a validated Controls from a decoded mapping, rejecting unknown or
+    missing keys."""
+    known = {f.name for f in fields(Controls)}
+    unknown = set(data) - known
+    if unknown:
+        raise ControlsError(f"unknown keys: {sorted(unknown)}")
+    missing = known - set(data)
+    if missing:
+        raise ControlsError(f"missing keys: {sorted(missing)}")
+    c = Controls(**data)
+    validate_controls(c)
+    return c

tests/test_player_controls.py

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+import pytest
+
+from player.controls import (
+    Controls,
+    CONTENT_POSITIONS,
+    ControlsError,
+    validate_controls,
+    parse_controls,
+)
+
+
+def test_content_positions_are_the_seven_from_the_spec():
+    assert CONTENT_POSITIONS == frozenset(
+        {"off", "white_noise", "music", "audio_track", "video", "music_video", "audio_video"}
+    )
+
+
+def test_valid_controls_pass_validation():
+    c = Controls(content="video", left=0, right=4, dark=2, light=2, volume=3, brightness=4)
+    validate_controls(c)  # does not raise
+
+
+def test_invalid_content_position_rejected():
+    c = Controls(content="bogus", left=0, right=0, dark=0, light=0, volume=0, brightness=0)
+    with pytest.raises(ControlsError):
+        validate_controls(c)
+
+
+@pytest.mark.parametrize("field", ["left", "right", "dark", "light", "volume", "brightness"])
+@pytest.mark.parametrize("bad", [-1, 5, True])
+def test_out_of_range_or_non_int_knob_rejected(field, bad):
+    kwargs = dict(content="off", left=0, right=0, dark=0, light=0, volume=0, brightness=0)
+    kwargs[field] = bad
+    with pytest.raises(ControlsError):
+        validate_controls(Controls(**kwargs))
+
+
+def test_parse_controls_from_mapping():
+    c = parse_controls(
+        {"content": "music_video", "left": 1, "right": 2, "dark": 3, "light": 0, "volume": 2, "brightness": 1}
+    )
+    assert c == Controls("music_video", 1, 2, 3, 0, 2, 1)
+
+
+def test_parse_controls_rejects_unknown_keys():
+    with pytest.raises(ControlsError):
+        parse_controls({"content": "off", "left": 0, "right": 0, "dark": 0,
+                        "light": 0, "volume": 0, "brightness": 0, "bogus": 1})
+
+
+def test_parse_controls_rejects_missing_keys():
+    with pytest.raises(ControlsError):
+        parse_controls({"content": "off", "left": 0})