add test for integral_scales

tests/timeseries/test_ntrfc_integral_scales.py

+import numpy as np
+
+from ntrfc.timeseries.integral_scales import integralscales
+
+
+def test_integralscales():
+
+    time = np.linspace(0,100,100000)
+    freq = 1
+    signal = np.sin(time*freq)+1
+
+    ts,ls=integralscales(signal,time)
+    assert np.isclose(ts,1,rtol=4e-3),"time scale not computed accurately"
+    assert np.isclose(ls,1,rtol=4e-3), "length scale not computed accurately"