@testset "read character matrix" begin
    mktemp() do path, _
        write(path, """
              1####2####
              ####3####4
              #5#6#7#8#9
              """)

        matrix = Advent.read_charmatrix(path)
        @test size(matrix) == (3, 10)
        @test matrix isa Matrix{Char}
        @test matrix[1,1] == '1'
        @test matrix[3,10] == '9'
    end
end
