private bool testBorders() {
	// test side borders are all '#'
	for (int i = 0; i < numRows; i++) {
		if (!(maze[i][0] == '#') || !(maze[i][numCols - 1] == '#')) {
			return false;
		}
	}

	// test top and bottom borders are all '#'
	for (int j = 0; j < numCols; j++) {
		if (!(maze[0][j] == '#') || !(maze[numRows - 1][j] == '#')) {
			return false;
		}
	}

	// all good
	return true;
}