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, 19 insertions, 0 deletions

diff --git a/src/tests/common/audio_test_fixture.cc b/src/tests/common/audio_test_fixture.cc
new file mode 100644
index 0000000..42bf27f
--- /dev/null
+++ b/src/tests/common/audio_test_fixture.cc
@@ -0,0 +1,19 @@
+// audio_test_fixture.cc - RAII wrapper for AudioEngine lifecycle
+// Simplifies audio test setup and teardown
+
+#include "audio_test_fixture.h"
+
+AudioTestFixture::AudioTestFixture() {
+  m_engine.init();
+}
+
+AudioTestFixture::~AudioTestFixture() {
+  m_engine.shutdown();
+}
+
+void AudioTestFixture::load_music(const TrackerScore* score,
+                                   const NoteParams* samples,
+                                   const AssetId* assets,
+                                   uint32_t count) {
+  m_engine.load_music_data(score, samples, assets, count);
+}