require 'minitest/autorun'
require_relative 'circular_buffer'

class CircularBufferTest < Minitest::Test
  def test_read_empty_buffer_throws_buffer_empty_exception
    buffer = CircularBuffer.new(1)
    assert_raises(CircularBuffer::BufferEmptyException) { buffer.read }
  end

  def test_write_and_read_back_one_item
    # skip
    buffer = CircularBuffer.new(1)
    buffer.write '1'
    assert_equal '1', buffer.read
    assert_raises(CircularBuffer::BufferEmptyException) { buffer.read }
  end

  def test_write_and_read_back_multiple_items
    # skip
    buffer = CircularBuffer.new(2)
    buffer.write '1'
    buffer.write '2'
    assert_equal '1', buffer.read
    assert_equal '2', buffer.read
    assert_raises(CircularBuffer::BufferEmptyException) { buffer.read }
  end

  def test_clearing_buffer
    # skip
    buffer = CircularBuffer.new(3)
    ('1'..'3').each { |i| buffer.write i }
    buffer.clear
    assert_raises(CircularBuffer::BufferEmptyException) { buffer.read }
    buffer.write '1'
    buffer.write '2'
    assert_equal '1', buffer.read
    buffer.write '3'
    assert_equal '2', buffer.read
  end

  def test_alternate_write_and_read
    # skip
    buffer = CircularBuffer.new(2)
    buffer.write '1'
    assert_equal '1', buffer.read
    buffer.write '2'
    assert_equal '2', buffer.read
  end

  def test_reads_back_oldest_item
    # skip
    buffer = CircularBuffer.new(3)
    buffer.write '1'
    buffer.write '2'
    buffer.read
    buffer.write '3'
    assert_equal '2', buffer.read
    assert_equal '3', buffer.read
  end

  def test_writing_to_a_full_buffer_throws_an_exception
    # skip
    buffer = CircularBuffer.new(2)
    buffer.write '1'
    buffer.write '2'
    assert_raises(CircularBuffer::BufferFullException) { buffer.write 'A' }
  end

  def test_overwriting_oldest_item_in_a_full_buffer
    # skip
    buffer = CircularBuffer.new(2)
    buffer.write '1'
    buffer.write '2'
    buffer.write! 'A'
    assert_equal '2', buffer.read
    assert_equal 'A', buffer.read
    assert_raises(CircularBuffer::BufferEmptyException) { buffer.read }
  end

  def test_forced_writes_to_non_full_buffer_should_behave_like_writes
    # skip
    buffer = CircularBuffer.new(2)
    buffer.write '1'
    buffer.write! '2'
    assert_equal '1', buffer.read
    assert_equal '2', buffer.read
    assert_raises(CircularBuffer::BufferEmptyException) { buffer.read }
  end

  def test_alternate_read_and_write_into_buffer_overflow
    # skip
    buffer = CircularBuffer.new(5)
    ('1'..'3').each { |i| buffer.write i }
    buffer.read
    buffer.read
    buffer.write '4'
    buffer.read
    ('5'..'8').each { |i| buffer.write i }
    buffer.write! 'A'
    buffer.write! 'B'
    ('6'..'8').each do |i|
      assert_equal i, buffer.read
    end
    assert_equal 'A', buffer.read
    assert_equal 'B', buffer.read
    assert_raises(CircularBuffer::BufferEmptyException) { buffer.read }
  end
end