@Test
	public void testIllegalConstruction() {
		Edge edge;
		try {
			edge = new Edge(null, testTile1, true);
			fail("IllegalArgumentException was expected");
		}
		catch (IllegalArgumentException e){
			//expected exception
		}
		try {
			edge = new Edge(null, null, false);
			fail("IllegalArgumentException was expected");
		}
		catch (IllegalArgumentException e){
			//expected exception
		}
		try {
			edge = new Edge(testTile1, testTile1, true);
			fail("IllegalArgumentException was expected");
		}
		catch (IllegalArgumentException e){
			//expected exception
		}
	}