Adding tests for the 3D case Hamiltonian pathsu

pyomo/contrib/piecewise/ordered_3d_j1_triangulation_data.py

@@ -9,17 +9,10 @@
 #  This software is distributed under the 3-clause BSD License.
 #  ___________________________________________________________________________
 
-
-"""
-This code was used to generate the data structure in this file. It should never
-need to be run again, but is here for the sake of documentation:
-
-import networkx as nx
+from pyomo.common.dependencies import networkx as nx
 import itertools
 
-# Get a list of 60 hamiltonian paths used in the 3d version of the ordered J1
-# triangulation, and dump it to stdout.
-if __name__ == '__main__':
+def _get_double_cube_graph():
     # Graph of a double cube
     sign_vecs = list(itertools.product((-1, 1), repeat=3))
     permutations = itertools.permutations(range(1, 4))
@@ -46,6 +39,17 @@
         neighbor_simplex = (tuple(neighbor_sign), simplex[1])
         G.add_edge(simplex, neighbor_simplex)
 
+    return G
+
+"""
+This code was used to generate the data structure in this file. It should never
+need to be run again, but is here for the sake of documentation:
+
+# Get a list of 60 hamiltonian paths used in the 3d version of the ordered J1
+# triangulation, and dump it to stdout.
+if __name__ == '__main__':
+    G = _get_double_cube_graph()
+
     # Each of these simplices has an outward face in the specified direction; also,
     # the +x simplex of one cube is adjacent to the -x simplex of a cube adjacent in
     # the x direction, and similarly for the others.

pyomo/contrib/piecewise/tests/test_triangulations.py

@@ -14,15 +14,16 @@
 from unittest import skipUnless
 import pyomo.common.unittest as unittest
 from pyomo.contrib.piecewise.ordered_3d_j1_triangulation_data import (
-    get_hamiltonian_paths
+    get_hamiltonian_paths,
+    _get_double_cube_graph,
 )
 from pyomo.contrib.piecewise.triangulations import (
     get_unordered_j1_triangulation,
     get_ordered_j1_triangulation,
     _get_Gn_hamiltonian,
     _get_grid_hamiltonian,
 )
-from pyomo.common.dependencies import numpy as np, numpy_available
+from pyomo.common.dependencies import numpy as np, numpy_available, networkx_available
 from math import factorial
 import itertools
 
@@ -224,6 +225,20 @@ def test_grid_hamiltonian_paths(self):
         self.check_grid_hamiltonian(3, 5)
         self.check_grid_hamiltonian(4, 3)
 
+@unittest.skipUnless(networkx_available, "Networkx is not available")
 class TestHamiltonianPaths(unittest.TestCase):
     def test_hamiltonian_paths(self):
+        G = _get_double_cube_graph()
+
         paths = get_hamiltonian_paths()
+        self.assertEqual(len(paths), 60)
+
+        for ((s1, t1), (s2, t2)), path in paths.items():
+            # ESJ: I'm not quite sure how to check this is *the right* path
+            # given the key?
+
+            # Check it's Hamiltonian
+            self.assertEqual(len(path), 48)
+            # Check it's a path
+            for idx in range(1, 48):
+                self.assertTrue(G.has_edge(path[idx - 1], path[idx]))