From 3bbb30d97e97d63c67cf9bb1973ca802fb59c778 Mon Sep 17 00:00:00 2001
From: nyanpasu64 <nyanpasu64@tuta.io>
Date: Sat, 17 Nov 2018 21:44:50 -0800
Subject: [PATCH] Add test for loud stereo overflowing

---
 tests/stereo in-phase.wav | Bin 0 -> 6444 bytes
 tests/test_wave.py        |  16 ++++++++++++++++
 2 files changed, 16 insertions(+)
 create mode 100644 tests/stereo in-phase.wav

diff --git a/tests/stereo in-phase.wav b/tests/stereo in-phase.wav
new file mode 100644
index 0000000000000000000000000000000000000000..f2a044c9ed468fb83e4c93a891152ff1c294e818
GIT binary patch
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diff --git a/tests/test_wave.py b/tests/test_wave.py
index cb8baee..31c2415 100644
--- a/tests/test_wave.py
+++ b/tests/test_wave.py
@@ -50,3 +50,19 @@ def test_wave_subsampling():
     for i in [-1000, 50000]:
         data = wave.get_around(i, region, stride)
         assert (data == 0).all()
+
+
+def test_stereo_doesnt_overflow():
+    """ Ensure loud stereo tracks do not overflow. """
+    wave = Wave(None, 'tests/stereo in-phase.wav')
+
+    samp = 100
+    stride = 1
+    data = wave.get_around(wave.nsamp // 2, samp, stride)
+    assert np.amax(data) > 0.99
+    assert np.amin(data) < -0.99
+
+    # In the absence of overflow, sine waves have no large jumps.
+    # In the presence of overflow, stereo sum will jump between INT_MAX and INT_MIN.
+    # np.mean and rescaling converts to 0.499... and -0.5, which is nearly 1.
+    assert np.amax(np.abs(np.diff(data))) < 0.5