fix(eq): re-apply equalizer when the native audio session rotates

ExoPlayer assigns a new audio session id after transient audio-focus interruptions (navigation prompts, radar warnings), leaving the AndroidEqualizer attached to the dead session so playback resumed without equalization until the next station switch. The session-id listener now detects genuine rotations through a dedicated guard and re-activates the equalizer with the current preset, gated on EQ availability to stay clear of player teardown/rebuild.
2026-07-10 18:51:45 +02:00
parent a31dc07318
commit 0ab63731d0
11 changed files with 1098 additions and 0 deletions
@@ -0,0 +1,99 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pluriwave/servicios/servicio_audio.dart';
+
+/// EQ audio-focus re-apply — pure decision predicate truth table.
+///
+/// Covers spec "EQ Audio-Focus Re-Apply Specification": whenever
+/// `androidAudioSessionIdStream` emits a new native session id mid-playback
+/// (audio-focus ducking by another app), the equalizer must be re-attached
+/// and the current preset's gains re-pushed, gated on EQ availability so it
+/// never races `_recrearPlayer()`'s teardown/rebuild.
+///
+/// [PluriWaveAudioHandler] cannot be instantiated in unit tests — its
+/// constructor builds a real `just_audio.AudioPlayer` that requires platform
+/// MethodChannels (confirmed by `servicio_audio_source_switch_test.dart`, "We
+/// cannot instantiate the handler in unit tests"). The only unit-testable
+/// surface is the pure, side-effect-free static predicate
+/// `debeReaplicarEcualizador`, extracted per the design's "Interfaces /
+/// Contracts" section. Listener wiring and the actual native re-attach are
+/// covered by manual on-device QA (spec's Testability Matrix), not here.
+void main() {
+  group('debeReaplicarEcualizador (EQ audio-focus re-apply predicate)', () {
+    test('rotation while playing returns true', () {
+      // Spec: Requirement "Session Id Rotation Triggers EQ Re-Apply" /
+      // Scenario "Session id rotates while playing".
+      expect(
+        PluriWaveAudioHandler.debeReaplicarEcualizador(
+          sessionId: 2,
+          ultimaSessionIdEq: 1,
+          eqDisponible: true,
+        ),
+        isTrue,
+        reason: 'a genuine id rotation with EQ available must re-apply',
+      );
+    });
+
+    test('same id re-emitted returns false', () {
+      // Spec: Scenario "Same id re-emitted produces no redundant re-apply".
+      expect(
+        PluriWaveAudioHandler.debeReaplicarEcualizador(
+          sessionId: 1,
+          ultimaSessionIdEq: 1,
+          eqDisponible: true,
+        ),
+        isFalse,
+        reason: 'a duplicate emission of the already-processed id is a no-op',
+      );
+    });
+
+    test('first activation / matching guard returns false', () {
+      // Spec: Scenario "First legitimate activation is not double-applied".
+      // Same shape as the duplicate-id case above, kept as a distinct named
+      // case per design's testing table to document intent: this represents
+      // the id emitted right after a station switch already set the guard
+      // (via _activarEcualizador() at the station-switch call site), not
+      // just an arbitrary repeated emission.
+      expect(
+        PluriWaveAudioHandler.debeReaplicarEcualizador(
+          sessionId: 1,
+          ultimaSessionIdEq: 1,
+          eqDisponible: true,
+        ),
+        isFalse,
+        reason:
+            'the first post-station-switch emission must not double-apply '
+            'on top of the station-switch path\'s own _activarEcualizador()',
+      );
+    });
+
+    test('null id returns false', () {
+      // Spec: Requirement "Session Id Rotation Triggers EQ Re-Apply"
+      // (non-null precondition).
+      expect(
+        PluriWaveAudioHandler.debeReaplicarEcualizador(
+          sessionId: null,
+          ultimaSessionIdEq: 1,
+          eqDisponible: true,
+        ),
+        isFalse,
+        reason: 'a null session id must never trigger a re-apply',
+      );
+    });
+
+    test('teardown gate returns false', () {
+      // Spec: Requirement "Re-Apply Is Gated On EQ Availability" / Scenario
+      // "Rotation during player teardown is safely skipped".
+      expect(
+        PluriWaveAudioHandler.debeReaplicarEcualizador(
+          sessionId: 9,
+          ultimaSessionIdEq: 1,
+          eqDisponible: false,
+        ),
+        isFalse,
+        reason:
+            'while _eqDisponible is false (mid _recrearPlayer teardown), '
+            're-apply must be skipped entirely to avoid racing the rebuild',
+      );
+    });
+  });
+}