Fix how runlemke() failure is checked in runLH() and runtrace()

src/lemke/bimatrix.py

@@ -341,7 +341,7 @@ def runLH(self, droppedlabel):
         # tabl.runlemke(verbose=True, lexstats=True, z0=gz0)
 
         result = lemke.runlemke(lcp=lcp)
-        if result is None:
+        if not result.success:
             raise RuntimeError("runlemke() failed to find a solution unexpectedly.")
 
         equilibrium = result.z[:-2]
@@ -418,7 +418,7 @@ def runtrace(self, xprior, yprior):
         lcp.d = np.hstack((Ay, xB, [1, 1]))
 
         result = lemke.runlemke(lcp=lcp)
-        if result is None:
+        if not result.success:
             raise RuntimeError("runlemke() failed to find a solution unexpectedly.")
 
         equilibrium = result.z[:-2]

tests/test_bimatrix_units.py

@@ -1,3 +1,4 @@
+import re
 import textwrap
 from fractions import Fraction
 
@@ -15,6 +16,7 @@
     trace_uniform_cmd,
     uniform,
 )
+from lemke.lemke import LcpResult
 from lemke.randomstart import MAX_ACCURACY
 from lemke.utils import MAXDECIMALS
 
@@ -185,6 +187,38 @@ def test_rejects_non_positive_num_priors(small_game_file, bad_priors):
         G.trace_random_priors(bad_priors)
 
 
+# ---   RUNLEMKE FAILURE  -------------------------------------------------
+@pytest.fixture
+def lemke_failure(monkeypatch):
+    failed_result = LcpResult(
+        success=False,
+        num_pivots=0,
+        basis=frozenset(),
+        z0=Fraction(-1),
+        z=(),
+        w=(),
+        ray_entering_variable=None,
+    )
+    monkeypatch.setattr(
+        "lemke.lemke.runlemke",
+        lambda **kwargs: failed_result,
+    )
+
+
+def test_runLH_throws_on_lemke_failure(lemke_failure, small_game_file):
+    G = bimatrix.from_file(small_game_file)
+
+    with pytest.raises(RuntimeError, match=re.escape("runlemke() failed")):
+        G.runLH(1)
+
+
+def test_runtrace_throws_on_lemke_failure(lemke_failure, small_game_file):
+    G = bimatrix.from_file(small_game_file)
+
+    with pytest.raises(RuntimeError, match=re.escape("runlemke() failed")):
+        G.runtrace([0.5, 0.5], [0.4, 0.6])
+
+
 # ---   HELPER FUNCTIONS   --------------------------------------------------------
 @pytest.mark.parametrize(
     "input, expected",