cover TransferFunction.returnScipySignalLTI() (backported from #438)

bnavigator · bnavigator · commit ba7817c02143 · 2020-08-02T23:16:28.000+02:00
diff --git a/control/tests/xferfcn_test.py b/control/tests/xferfcn_test.py
@@ -4,6 +4,8 @@
 # RMM, 30 Mar 2011 (based on TestXferFcn from v0.4a)
 
 import unittest
+import pytest
+
 import sys as pysys
 import numpy as np
 from control.statesp import StateSpace, _convertToStateSpace, rss
@@ -912,8 +914,8 @@ def test_repr(self):
                     np.testing.assert_array_almost_equal(
                         H.den[p][m], H2.den[p][m])
             self.assertEqual(H.dt, H2.dt)
-    
-    def test_sample_system_prewarping(self): 
+
+    def test_sample_system_prewarping(self):
         """test that prewarping works when converting from cont to discrete time system"""
         A = np.array([
             [ 0.00000000e+00,  1.00000000e+00,  0.00000000e+00, 0.00000000e+00],
@@ -929,10 +931,29 @@ def test_sample_system_prewarping(self):
         plant = ss2tf(plant)
         plant_d_warped = plant.sample(Ts, 'bilinear', prewarp_frequency=wwarp)
         np.testing.assert_array_almost_equal(
-            evalfr(plant, wwarp*1j), 
-            evalfr(plant_d_warped, np.exp(wwarp*1j*Ts)), 
+            evalfr(plant, wwarp*1j),
+            evalfr(plant_d_warped, np.exp(wwarp*1j*Ts)),
             decimal=4)
 
+@pytest.mark.parametrize("dt",
+                         [None,
+                          0,
+                          pytest.param(1, marks=pytest.mark.xfail(
+                              reason="not implemented")),
+                          pytest.param(1, marks=pytest.mark.xfail(
+                              reason="not implemented"))])
+def test_returnScipySignalLTI(dt):
+    """Test returnScipySignalLTI method"""
+    sys = TransferFunction([[[11], [12], [13]],
+                            [[21], [22], [23]]],
+                           [[[1, -1]] * 3] * 2,
+                           dt)
+    sslti = sys.returnScipySignalLTI()
+    for i in range(2):
+        for j in range(3):
+            np.testing.assert_allclose(sslti[i][j].num, sys.num[i][j])
+            np.testing.assert_allclose(sslti[i][j].den, sys.den[i][j])
+
 
 if __name__ == "__main__":
     unittest.main()
