Add tests for subsampling

tests/test_channel.py

@@ -0,0 +1,37 @@
+import pytest
+from hypothesis import given, example
+from hypothesis.strategies import integers
+
+
+from ovgenpy.channel import ChannelConfig, Channel
+from ovgenpy.ovgenpy import default_config
+
+
+positive = integers(min_value=1)
+
+@given(subsampling=positive, trigger_width_ratio=positive, render_width_ratio=positive)
+def test_channel_subsampling(
+    subsampling: int,
+    trigger_width_ratio: int,
+    render_width_ratio: int,
+):
+    """ Ensure nsamp and trigger/render subsampling are computed correctly. """
+
+    ccfg = ChannelConfig(
+        'tests/sine440.wav',
+        trigger_width_ratio=trigger_width_ratio,
+        render_width_ratio=render_width_ratio,
+    )
+    cfg = default_config(subsampling=subsampling)
+    channel = Channel(ccfg, cfg)
+    assert channel.wave.smp_s == 48000
+
+    ideal_nsamp = round(cfg.render_width_s * channel.wave.smp_s / subsampling)
+    assert channel.nsamp == pytest.approx(ideal_nsamp, 1)
+    assert channel.trigger_subsampling == subsampling * trigger_width_ratio
+    assert channel.render_subsampling == subsampling * render_width_ratio
+
+
+
+# line_color is tested in test_renderer.py
+# todo test ChannelConfig.ampl_ratio