test: hazards, ladders and one-way platforms

tests/test_ladder.py

@@ -0,0 +1,50 @@
+import pytest
+
+from game import constants
+from tests.support import makeWorld
+from game.sim.inputCommand import InputCommand
+
+
+ladderLevel = [
+    "  H  ",
+    "  H  ",
+    "  H  ",
+    "XXXXX",
+]
+
+
+def seatOnLadder(world):
+    world.player.x = 2 * constants.tileSize
+    world.player.y = 2 * constants.tileSize
+    world.player.vy = 0.0
+
+
+def test_climbLadderReducesHeight():
+    world = makeWorld(ladderLevel)
+    seatOnLadder(world)
+    startY = world.player.y
+    for _ in range(8):
+        world.step(InputCommand(up=True))
+    assert world.player.onLadder
+    assert world.player.y < startY - 6.0
+
+
+def test_ladderHoverIgnoresGravity():
+    world = makeWorld(ladderLevel)
+    seatOnLadder(world)
+    for _ in range(6):
+        world.step(InputCommand(up=True))
+    restingY = world.player.y
+    for _ in range(6):
+        world.step(InputCommand())
+    assert world.player.y == pytest.approx(restingY, abs=0.5)
+
+
+def test_leavingLadderTileDropsClimbState():
+    world = makeWorld(ladderLevel)
+    seatOnLadder(world)
+    world.step(InputCommand(up=True))
+    assert world.player.onLadder
+    world.player.x = 0.0
+    world.step(InputCommand())
+    assert not world.player.onLadder