1 files changed, 211 insertions, 0 deletions
diff --git a/src/tests/test_silent_backend.cc b/src/tests/test_silent_backend.cc
new file mode 100644
index 0000000..8daacf7
--- /dev/null
+++ b/src/tests/test_silent_backend.cc
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+// This file is part of the 64k demo project.
+// It tests the SilentBackend for audio testing without hardware.
+// Verifies audio.cc functionality using silent backend.
+
+#include "audio/audio.h"
+#include "audio/audio_engine.h"
+#include "audio/backend/silent_backend.h"
+#include "audio/synth.h"
+#include <assert.h>
+#include <stdio.h>
+
+#if !defined(STRIP_ALL)
+
+// Test: SilentBackend initialization and lifecycle
+void test_silent_backend_lifecycle() {
+  SilentBackend backend;
+
+  assert(!backend.is_initialized());
+  assert(!backend.is_started());
+
+  backend.init();
+  assert(backend.is_initialized());
+  assert(!backend.is_started());
+
+  backend.start();
+  assert(backend.is_initialized());
+  assert(backend.is_started());
+
+  backend.shutdown();
+  assert(!backend.is_initialized());
+  assert(!backend.is_started());
+
+  printf("SilentBackend lifecycle test PASSED\n");
+}
+
+// Test: Audio system with SilentBackend
+void test_audio_with_silent_backend() {
+  SilentBackend backend;
+  audio_set_backend(&backend);
+
+  audio_init();
+  assert(backend.is_initialized());
+
+  audio_start();
+  assert(backend.is_started());
+
+  audio_shutdown();
+  assert(!backend.is_initialized());
+
+  printf("Audio with SilentBackend test PASSED\n");
+}
+
+// Test: Peak control in SilentBackend
+void test_silent_backend_peak() {
+  SilentBackend backend;
+  audio_set_backend(&backend);
+
+  audio_init();
+
+  // Default peak should be 0
+  assert(backend.get_realtime_peak() == 0.0f);
+  assert(audio_get_realtime_peak() == 0.0f);
+
+  // Set test peak
+  backend.set_peak(0.75f);
+  assert(backend.get_realtime_peak() == 0.75f);
+  assert(audio_get_realtime_peak() == 0.75f);
+
+  // Reset
+  backend.set_peak(0.0f);
+  assert(backend.get_realtime_peak() == 0.0f);
+
+  audio_shutdown();
+
+  printf("SilentBackend peak control test PASSED\n");
+}
+
+// Test: Frame and voice tracking
+void test_silent_backend_tracking() {
+  SilentBackend backend;
+  audio_set_backend(&backend);
+
+  AudioEngine engine;
+  engine.init();
+
+  // Initial state
+  assert(backend.get_frames_rendered() == 0);
+  assert(backend.get_voice_trigger_count() == 0);
+
+  // Create a dummy spectrogram
+  float data[DCT_SIZE * 2] = {0};
+  Spectrogram spec = {data, data, 2};
+  int id = synth_register_spectrogram(&spec);
+
+  // Trigger a voice
+  synth_trigger_voice(id, 0.8f, 0.0f);
+  assert(backend.get_voice_trigger_count() == 1);
+
+  // Render audio (calls on_frames_rendered)
+  audio_render_ahead(0.0f, 0.1f); // Render ~0.1 seconds
+  assert(backend.get_frames_rendered() > 0);
+
+  // Reset stats
+  backend.reset_stats();
+  assert(backend.get_frames_rendered() == 0);
+  assert(backend.get_voice_trigger_count() == 0);
+
+  engine.shutdown();
+  audio_shutdown();
+
+  printf("SilentBackend tracking test PASSED\n");
+}
+
+// Test: Playback time with SilentBackend
+void test_audio_playback_time() {
+  SilentBackend backend;
+  audio_set_backend(&backend);
+
+  AudioEngine engine;
+  engine.init();
+  audio_start();
+
+  // Initial playback time should be 0
+  float t0 = audio_get_playback_time();
+  assert(t0 == 0.0f);
+
+  // Render some audio
+  audio_render_ahead(0.5f, 0.1f); // Advance music time to 0.5s
+
+  // Playback time should advance based on frames rendered
+  // Note: audio_get_playback_time() tracks cumulative frames consumed
+  float t1 = audio_get_playback_time();
+  assert(t1 >= 0.0f); // Should have advanced
+
+  // Render more
+  audio_render_ahead(1.0f, 0.5f);
+  float t2 = audio_get_playback_time();
+  assert(t2 >= t1); // Should continue advancing
+
+  engine.shutdown();
+  audio_shutdown();
+
+  printf("Audio playback time test PASSED\n");
+}
+
+// Test: Buffer management with partial writes
+void test_audio_buffer_partial_writes() {
+  SilentBackend backend;
+  audio_set_backend(&backend);
+
+  AudioEngine engine;
+  engine.init();
+  audio_start();
+
+  // Fill buffer multiple times to test wraparound
+  // Note: With SilentBackend, frames_rendered won't increase because
+  // there's no audio callback consuming from the ring buffer
+  for (int i = 0; i < 10; ++i) {
+    audio_render_ahead((float)i * 0.1f, 0.1f);
+  }
+
+  // Buffer should have handled multiple writes correctly (no crash)
+  // We can't check frames_rendered with SilentBackend since there's
+  // no audio callback to consume from the ring buffer
+  audio_update(); // Should not crash
+
+  engine.shutdown();
+  audio_shutdown();
+
+  printf("Audio buffer partial writes test PASSED\n");
+}
+
+// Test: audio_update() with SilentBackend
+void test_audio_update() {
+  SilentBackend backend;
+  audio_set_backend(&backend);
+
+  AudioEngine engine;
+  engine.init();
+  audio_start();
+
+  // audio_update() should be callable without crashing
+  audio_update();
+  audio_update();
+  audio_update();
+
+  engine.shutdown();
+  audio_shutdown();
+
+  printf("Audio update test PASSED\n");
+}
+
+#endif /* !defined(STRIP_ALL) */
+
+int main() {
+#if !defined(STRIP_ALL)
+  printf("Running SilentBackend tests...\n");
+  test_silent_backend_lifecycle();
+  test_audio_with_silent_backend();
+  test_silent_backend_peak();
+  test_silent_backend_tracking();
+  test_audio_playback_time();
+  test_audio_buffer_partial_writes();
+  test_audio_update();
+  printf("All SilentBackend tests PASSED\n");
+  return 0;
+#else
+  printf("SilentBackend tests skipped (STRIP_ALL enabled)\n");
+  return 0;
+#endif /* !defined(STRIP_ALL) */
+}