Factor common test patterns into reusable utilitiesHEADmain

Refactor duplicated test setup/teardown code into shared fixtures:
- test_math_helpers.h: Float comparison (test_near, test_near_vec3)
- AudioTestFixture: RAII wrapper for AudioEngine lifecycle
- EffectTestFixture: Combined WebGPU + AudioEngine + MainSequence

Migrated 9 test files (3 math, 6 audio) to use fixtures.
Net reduction: 54 LOC (178 insertions, 232 deletions).

All 34 tests passing.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 5 insertions, 12 deletions

diff --git a/src/tests/audio/test_silent_backend.cc b/src/tests/audio/test_silent_backend.cc
index 8daacf7..cc98139 100644
--- a/src/tests/audio/test_silent_backend.cc
+++ b/src/tests/audio/test_silent_backend.cc
@@ -6,6 +6,7 @@
 #include "audio/audio_engine.h"
 #include "audio/backend/silent_backend.h"
 #include "audio/synth.h"
+#include "../common/audio_test_fixture.h"
 #include <assert.h>
 #include <stdio.h>
 
@@ -80,8 +81,7 @@ void test_silent_backend_tracking() {
   SilentBackend backend;
   audio_set_backend(&backend);
 
-  AudioEngine engine;
-  engine.init();
+  AudioTestFixture fixture;
 
   // Initial state
   assert(backend.get_frames_rendered() == 0);
@@ -105,7 +105,6 @@ void test_silent_backend_tracking() {
   assert(backend.get_frames_rendered() == 0);
   assert(backend.get_voice_trigger_count() == 0);
 
-  engine.shutdown();
   audio_shutdown();
 
   printf("SilentBackend tracking test PASSED\n");
@@ -116,8 +115,7 @@ void test_audio_playback_time() {
   SilentBackend backend;
   audio_set_backend(&backend);
 
-  AudioEngine engine;
-  engine.init();
+  AudioTestFixture fixture;
   audio_start();
 
   // Initial playback time should be 0
@@ -137,7 +135,6 @@ void test_audio_playback_time() {
   float t2 = audio_get_playback_time();
   assert(t2 >= t1); // Should continue advancing
 
-  engine.shutdown();
   audio_shutdown();
 
   printf("Audio playback time test PASSED\n");
@@ -148,8 +145,7 @@ void test_audio_buffer_partial_writes() {
   SilentBackend backend;
   audio_set_backend(&backend);
 
-  AudioEngine engine;
-  engine.init();
+  AudioTestFixture fixture;
   audio_start();
 
   // Fill buffer multiple times to test wraparound
@@ -164,7 +160,6 @@ void test_audio_buffer_partial_writes() {
   // 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");
@@ -175,8 +170,7 @@ void test_audio_update() {
   SilentBackend backend;
   audio_set_backend(&backend);
 
-  AudioEngine engine;
-  engine.init();
+  AudioTestFixture fixture;
   audio_start();
 
   // audio_update() should be callable without crashing
@@ -184,7 +178,6 @@ void test_audio_update() {
   audio_update();
   audio_update();
 
-  engine.shutdown();
   audio_shutdown();
 
   printf("Audio update test PASSED\n");