require_relative 'test_helper'
class TestTerm < MiniTest::Unit::TestCase
  def test_initializer
    assert_equal 0, Term.new.coefficient
    assert_equal 0, Term.new.exponent
  end

  def test_parsing_with_standard_format
    assert_equal 4, Term.parse('4x^2').coefficient
    assert_equal 2, Term.parse('4x^2').exponent
  end

  def test_parsing_with_default_exponent_equal_to_one
    assert_equal 1, Term.parse('1x').coefficient
    assert_equal 1, Term.parse('1x').exponent
  end

  def test_parsing_with_default_coefficient_equal_to_one
    assert_equal 1.0, Term.parse('x^6').coefficient
    assert_equal 6, Term.parse('x^6').exponent
  end

  def  test_parsing_variable_omitted
    assert_equal 6, Term.parse('6').coefficient
    assert_equal 0, Term.parse('6').exponent
  end

  def test_invalid_string_raises_not_parsable_error
    ['6x^ -5', '6^20',  '2 2', 'xx', '2 ^ x'].each do |not_parsable_string|
      assert_raises NotParsableError do
        term = Term.parse not_parsable_string
      end
    end
  end

  def testing_to_s
    assert_equal "+ 6 ", Term.parse('6').to_s
  end
end