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, 23 insertions, 0 deletions

diff --git a/src/tests/common/effect_test_fixture.cc b/src/tests/common/effect_test_fixture.cc
new file mode 100644
index 0000000..b403ef6
--- /dev/null
+++ b/src/tests/common/effect_test_fixture.cc
@@ -0,0 +1,23 @@
+// effect_test_fixture.cc - Combined WebGPU + AudioEngine + MainSequence fixture
+// Simplifies GPU effect test setup
+
+#include "effect_test_fixture.h"
+#include <stdio.h>
+
+EffectTestFixture::EffectTestFixture() {}
+
+EffectTestFixture::~EffectTestFixture() {
+  if (m_initialized) {
+    m_gpu.shutdown();
+  }
+}
+
+bool EffectTestFixture::init() {
+  if (!m_gpu.init()) {
+    fprintf(stdout, "  ⚠ WebGPU unavailable - skipping test\n");
+    return false;
+  }
+  m_sequence.init_test(ctx());
+  m_initialized = true;
+  return true;
+}