Add unit test for clock_error()

Author: mhostetter

tests/simulation/test_clock_error.py

@@ -0,0 +1,38 @@
+import numpy as np
+import pytest
+
+import sdr
+
+
+@pytest.mark.parametrize("error", [1e-9, 1e-6, 1e-3, 1e-1])
+def test_real_passband(error):
+    sample_rate = 2e6
+    freq = 100e3
+    duration = 1000e-6
+    x = sdr.sinusoid(duration, freq, sample_rate=sample_rate, complex=False)
+
+    y = sdr.clock_error(x, error)
+
+    error = -error / (1 + error)
+    z = sdr.clock_error(y, error)
+
+    # Ignore the first and last 5 sample due to filter effects. The signals aren't perfectly identical also due
+    # to filter effects. Use abolute tolerance to verify the signals are spinning at different rates.
+    np.testing.assert_allclose(x[5 : z.size - 5], z[5:-5], atol=0.01)
+
+
+@pytest.mark.parametrize("error", [1e-9, 1e-6, 1e-3, 1e-1])
+def test_complex_passband(error):
+    sample_rate = 2e6
+    center_freq = 1e6
+    duration = 1000e-6
+    x = sdr.sinusoid(duration, 0, sample_rate=sample_rate)
+
+    y = sdr.clock_error(x, error, 0, center_freq, sample_rate=sample_rate)
+
+    error = -error / (1 + error)
+    z = sdr.clock_error(y, error, 0, center_freq, sample_rate=sample_rate)
+
+    # Ignore the first and last 5 sample due to filter effects. The signals aren't perfectly identical also due
+    # to filter effects. Use abolute tolerance to verify the signals are spinning at different rates.
+    np.testing.assert_allclose(x[5 : z.size - 5], z[5:-5], atol=0.01)