add test to cover _rss_generate (rss and drss) errors on invalid input

bnavigator · bnavigator · commit e50ce23d2dd7 · 2021-03-24T23:00:05.000+01:00
diff --git a/control/statesp.py b/control/statesp.py
@@ -1465,7 +1465,7 @@ def _rss_generate(states, inputs, outputs, cdtype, strictly_proper=False):
     if outputs < 1 or outputs % 1:
         raise ValueError("outputs must be a positive integer.  outputs = %g." %
                          outputs)
-    if cdtype not in ['c', 'd']:   # pragma: no cover
+    if cdtype not in ['c', 'd']:
         raise ValueError("cdtype must be `c` or `d`")
 
     # Make some poles for A.  Preallocate a complex array.
@@ -1835,7 +1835,7 @@ def rss(states=1, outputs=1, inputs=1, strictly_proper=False):
         Number of state variables
     inputs : int
         Number of system inputs
-    outputs : inte
+    outputs : int
         Number of system outputs
     strictly_proper : bool, optional
         If set to 'True', returns a proper system (no direct term).
diff --git a/control/tests/statesp_test.py b/control/tests/statesp_test.py
@@ -19,7 +19,7 @@
 from control.dtime import sample_system
 from control.lti import evalfr
 from control.statesp import (StateSpace, _convert_to_statespace, drss,
-                             rss, ss, tf2ss, _statesp_defaults)
+                             rss, ss, tf2ss, _statesp_defaults, _rss_generate)
 from control.tests.conftest import ismatarrayout, slycotonly
 from control.xferfcn import TransferFunction, ss2tf
 
@@ -866,6 +866,17 @@ def test_strictly_proper(self, strictly_proper):
                 break
         assert np.all(sys.D == 0.) == strictly_proper
 
+    @pytest.mark.parametrize('par, errmatch',
+                             [((-1, 1, 1, 'c'), 'states must be'),
+                              ((1, -1, 1, 'c'), 'inputs must be'),
+                              ((1, 1, -1, 'c'), 'outputs must be'),
+                              ((1, 1, 1, 'x'), 'cdtype must be'),
+                              ])
+    def test_rss_invalid(self, par, errmatch):
+        """Test invalid inputs for rss() and drss()."""
+        with pytest.raises(ValueError, match=errmatch):
+            _rss_generate(*par)
+
 
 class TestDrss:
     """These are tests for the proper functionality of statesp.drss."""
