test_expand = ->
  run_test [

    # general cases

    "expand(1/(x+1)/(x+2))",
    "1/(x+1)-1/(x+2)",

    "expand((2x^3-x+2)/(x^2-2x+1))",
    "4+2*x+5/(x-1)+3/(x^2-2*x+1)",

    "expand(1/x^2/(x-1))",
    "-1/(x^2)-1/x+1/(x-1)",

    "p=5s+2",
    "",

    "q=(s+1)*(s+2)^2",
    "",

    "expand(p/q)",
    "-3/(s+1)+3/(s+2)+8/(s^2+4*s+4)",

    # ensure denominators are expanded (result seems preferable that way)

    "q=(x-1)*(x-2)^3",
    "",

    "expand(1/q)",
    "1/(x^3-6*x^2+12*x-8)+1/(x-2)-1/(x-1)-1/(x^2-4*x+4)",

    # fractional poles

    "expand(1/(x+1/2)/(x+1/3))",
    "-12/(2*x+1)+18/(3*x+1)",

    # expand tensor

    "f=1/(x+1)/(x+2)",
    "",

    "g=1/(x+1)-1/(x+2)",
    "",

    "expand([[f,f],[f,f]])-[[g,g],[g,g]]",
    "[[0,0],[0,0]]",

    # denominator normalized?

    "expand(1/(1+1/x))",
    "1-1/(x+1)",

    # poles at zero

    "expand(1/x/(x+1))",
    "1/x-1/(x+1)",

    "expand(1/x^2/(x+1))",
    #"x^(-2)-1/x+1/(x+1)",
    "1/x^2-1/x+1/(x+1)",

    # other corner cases

    "expand(1/x)",
    "1/x",

    "expand(1/x^2)",
    #"x^(-2)",
    "1/x^2",

    "expand(1/(x^2-4x+4))",
    "1/(x^2-4*x+4)",

    # cases where nothing can be done

    "expand(sin(x))",
    "sin(x)",

    "expand(x)",
    "x",

    "expand(1/sin(x))",
    # unclear why the extra parens are added but no biggie
    "1/(sin(x))",

    # note that expand isn't needed to execute the
    # multiplications, expand does something
    # different.
    "expand(expand((sin(x)+1)^2))",
    "1+sin(x)^2+2*sin(x)",

  ]