def test_get_next_with_no_child_and_all_open_neighbors_returns_first_available(
):
"""
Verifies that `get_next` returns the first available neighbor if all are open.
"""
grid = Grid(((3, -1, -1), (-1, 2, -1), (0, -1, -1)))
assert get_next(grid[0][0]).location == (0, 1)
assert get_next(grid[1][1]).location == (0, 1)
def test_get_next_with_last_child_returns_none():
"""
Verifies that `get_next` on a point with its last possible child returns None.
"""
grid = Grid(((3, -1, -1), (-1, 2, -1), (0, -1, -1)))
grid[1][1].child = grid[1][0]
assert get_next(grid[1][1]) is None
def test_get_next_with_first_of_multiple_children_returns_next_child():
"""
Verifies that `get_next` on a point with a child returns the correct next point.
"""
grid = Grid(((3, -1, -1), (-1, 2, -1), (0, -1, -1)))
grid[1][1].child = grid[0][1]
assert get_next(grid[1][1]).location == (1, 2)
def test_get_next_with_one_remaining_segment_skips_point_on_new_segment():
"""
Verifies that `get_next`, on last allowed segment, skips points on new segments.
"""
grid = Grid(((-1, -1, -1, -1), (1, -1, -1, 0)))
grid[1][0].child = grid[1][1]
assert get_next(grid[1][1]).location == (1, 2)
def test_get_next_with_greater_than_two_remaining_segments_skips_sinks():
"""
Verifies that `get_next` skips a sink not on the last allowed segment.
"""
grid = Grid(((-1, 0, -1), (4, -1, 0), (-1, -1, -1)))
current = grid[1][1]
# Set partial path to current
grid[1][0].child = current
assert get_next(current).location == (2, 1)
def test_get_next_with_no_child_and_some_open_neighbors_returns_first_available(
):
"""
Verifies that `get_next` returns the first available neighbor if some are open.
"""
grid = Grid(((3, -1, -1), (-1, 2, -1), (0, -1, -1)))
# Set partial path from "3"
draw_path(grid, ((0, 0), (0, 1), (0, 2), (1, 2)))
assert get_next(grid[1][1]).location == (2, 1)
def test_get_next_with_no_child_and_no_open_neighbors_returns_none():
"""Verifies that `get_next` returns None if no neighbors are open."""
grid = Grid(((4, -1, 1), (0, -1, -1), (-1, -1, 0)))
# Set (incorrect) path from "4"
draw_path(grid, ((0, 0), (0, 1), (1, 1), (1, 2), (2, 2)))
assert get_next(grid[1][2]) is None