chore: initial commit

choir-mixer/tests/test_mixer.py

@@ -0,0 +1,66 @@
+import numpy as np
+from mixer import normalize_rms, mix_streams, soft_limit
+
+TARGET_DBFS = -20
+
+
+class TestNormalizeRms:
+    def test_silence_stays_silent(self, silence):
+        result = normalize_rms(silence, TARGET_DBFS)
+        assert np.allclose(result, 0.0)
+
+    def test_quiet_tone_gets_louder(self, quiet_tone):
+        original_rms = np.sqrt(np.mean(quiet_tone ** 2))
+        result = normalize_rms(quiet_tone, TARGET_DBFS)
+        result_rms = np.sqrt(np.mean(result ** 2))
+        assert result_rms > original_rms
+
+    def test_loud_tone_gets_quieter(self, loud_tone):
+        original_rms = np.sqrt(np.mean(loud_tone ** 2))
+        result = normalize_rms(loud_tone, TARGET_DBFS)
+        result_rms = np.sqrt(np.mean(result ** 2))
+        assert result_rms < original_rms
+
+    def test_normalized_to_target(self, loud_tone):
+        result = normalize_rms(loud_tone, TARGET_DBFS)
+        result_rms = np.sqrt(np.mean(result ** 2))
+        result_dbfs = 20 * np.log10(result_rms + 1e-10)
+        assert abs(result_dbfs - TARGET_DBFS) < 1.0  # within 1 dB
+
+
+class TestMixStreams:
+    def test_single_stream_unchanged(self, loud_tone):
+        result = mix_streams([loud_tone])
+        assert np.allclose(result, loud_tone)
+
+    def test_two_streams_summed(self, loud_tone):
+        result = mix_streams([loud_tone, loud_tone])
+        # Two identical streams summed should be louder
+        assert np.max(np.abs(result)) > np.max(np.abs(loud_tone))
+
+    def test_empty_list_returns_silence(self, silence):
+        result = mix_streams([])
+        assert result.shape[0] == 960
+        assert np.allclose(result, 0.0)
+
+    def test_different_lengths_uses_shortest(self):
+        short = np.ones(480, dtype=np.float32) * 0.5
+        long = np.ones(960, dtype=np.float32) * 0.5
+        result = mix_streams([short, long])
+        assert result.shape[0] == 480
+
+
+class TestSoftLimit:
+    def test_quiet_signal_unchanged(self, quiet_tone):
+        result = soft_limit(quiet_tone)
+        assert np.allclose(result, quiet_tone, atol=0.001)
+
+    def test_clipping_signal_contained(self, clipping_tone):
+        result = soft_limit(clipping_tone)
+        assert np.max(np.abs(result)) <= 1.0
+
+    def test_preserves_sign(self, clipping_tone):
+        result = soft_limit(clipping_tone)
+        # Signs should match where input is non-zero
+        nonzero = np.abs(clipping_tone) > 0.01
+        assert np.all(np.sign(result[nonzero]) == np.sign(clipping_tone[nonzero]))