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class Polynomial
def initialize(coefs)
if coefs.nil? || !coefs.kind_of?(Array) || coefs.size < 2
raise ArgumentError, "Need at least 2 coefficients."
end
@coefs = coefs
end
def to_s
power = @coefs.size
parts = @coefs.map do |coef|
power -= 1
coef = coef.to_i
unless coef == 0
part = (power == 0 || coef.abs != 1) ? coef.to_s : (coef > 0 ? '' : '-')
part += (power == 0) ? '' : (power == 1) ? 'x' : "x^#{power}"
end
end.compact
return parts.empty? ? '0' : (parts.compact * '+').gsub('+-', '-')
end
end
# assuming that your solution is polynomial.rb
require 'test/unit'
require 'test/unit/ui/console/testrunner'
require 'polynomial'
class PolynomialTest < Test::Unit::TestCase
def test_first_negative
assert_poly("-3x^4-4x^3+x^2+6", -3, -4, 1, 0, 6)
end
def test_simple
assert_poly("x^2+2", 1, 0, 2)
end
def test_first_minus_one
assert_poly("-x^3-2x^2+3x", -1, -2, 3, 0)
end
def test_all_zero
assert_poly("0", 0, 0, 0)
end
def test_last_one
assert_poly("x-1", 1, -1)
end
def test_error
e = assert_raise(ArgumentError) { Polynomial.new([1]) }
assert_match(/Need at least 2 coefficients/, e.message)
end
def assert_poly(result, *c)
assert_equal(result, Polynomial.new(c).to_s)
end
end
Test::Unit::UI::Console::TestRunner.run(PolynomialTest)
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