test_basic.py

import unittest
from astar import AStar

class BasicAStar(AStar):
 def __init__(self, nodes):
 self.nodes = nodes

 def neighbors(self, n):
 for n1, d in self.nodes[n]:
 yield n1

 def distance_between(self, n1, n2):
 for n, d in self.nodes[n1]:
 if n == n2:
 return d
 
 def heuristic_cost_estimate(self, current, goal):
 return 1
 
 def is_goal_reached(self, current, goal):
 return current == goal

class BasicTests(unittest.TestCase):

 def test_bestpath(self):
 """ensure that we take the shortest path, and not the path with less elements.
 the path with less elements is A -> B with a distance of 100
 the shortest path is A -> C -> D -> B with a distance of 60
 """
 nodes = {'A': [('B', 100), ('C', 20)],
 'C': [('D', 20)], 
 'D': [('B', 20)]}

 path = BasicAStar(nodes).astar('A', 'B')
 self.assertIsNotNone(path)
 if path:
 path = list(path)
 self.assertEqual(4, len(path))
 for i, n in enumerate('ACDB'):
 self.assertEqual(n, path[i])

 def test_issue_15(self):
 """This test case reproduces https://github.com/jrialland/python-astar/issues/15.
 B has no neighbors, therefore the computation should return None and not raise an exception.
 """
 node = {
 'A': [('B', 200000)],
 'C': [('D', 200000)],
 'D': [('E', 200000)],
 'E': [('F', 200000)],
 'B': [],
 'F': []
 }
 path = BasicAStar(node).astar('A', 'D')
 self.assertIsNone(path)

if __name__ == '__main__':
 unittest.main()