python/exercises/circular-buffer/circular_buffer_test.py

import unittest

from circular_buffer import (
    CircularBuffer,
    BufferFullException,
    BufferEmptyException
)


class CircularBufferTest(unittest.TestCase):
    def test_read_empty_buffer(self):
        buf = CircularBuffer(1)
        with self.assertRaises(BufferEmptyException):
            buf.read()

    def test_write_and_read_back_one_item(self):
        buf = CircularBuffer(1)
        buf.write('1')
        self.assertEqual('1', buf.read())
        with self.assertRaises(BufferEmptyException):
            buf.read()

    def test_write_and_read_back_multiple_items(self):
        buf = CircularBuffer(2)
        buf.write('1')
        buf.write('2')
        self.assertEqual(buf.read(), '1')
        self.assertEqual(buf.read(), '2')
        with self.assertRaises(BufferEmptyException):
            buf.read()

    def test_clearing_buffer(self):
        buf = CircularBuffer(3)
        for c in '123':
            buf.write(c)
        buf.clear()
        with self.assertRaises(BufferEmptyException):
            buf.read()
        buf.write('1')
        buf.write('2')
        self.assertEqual(buf.read(), '1')
        buf.write('3')
        self.assertEqual(buf.read(), '2')

    def test_alternate_write_and_read(self):
        buf = CircularBuffer(2)
        buf.write('1')
        self.assertEqual(buf.read(), '1')
        buf.write('2')
        self.assertEqual(buf.read(), '2')

    def test_read_back_oldest_item(self):
        buf = CircularBuffer(3)
        buf.write('1')
        buf.write('2')
        buf.read()
        buf.write('3')
        buf.read()
        self.assertEqual(buf.read(), '3')

    def test_write_full_buffer(self):
        buf = CircularBuffer(2)
        buf.write('1')
        buf.write('2')
        with self.assertRaises(BufferFullException):
            buf.write('A')

    def test_overwrite_full_buffer(self):
        buf = CircularBuffer(2)
        buf.write('1')
        buf.write('2')
        buf.overwrite('A')
        self.assertEqual(buf.read(), '2')
        self.assertEqual(buf.read(), 'A')
        with self.assertRaises(BufferEmptyException):
            buf.read()

    def test_overwrite_non_full_buffer(self):
        buf = CircularBuffer(2)
        buf.overwrite('1')
        buf.overwrite('2')
        self.assertEqual(buf.read(), '1')
        self.assertEqual(buf.read(), '2')
        with self.assertRaises(BufferEmptyException):
            buf.read()

    def test_alternate_read_and_overwrite(self):
        buf = CircularBuffer(5)
        for c in '123':
            buf.write(c)
        buf.read()
        buf.read()
        buf.write('4')
        buf.read()
        for c in '5678':
            buf.write(c)
        buf.overwrite('A')
        buf.overwrite('B')
        self.assertEqual(buf.read(), '6')
        self.assertEqual(buf.read(), '7')
        self.assertEqual(buf.read(), '8')
        self.assertEqual(buf.read(), 'A')
        self.assertEqual(buf.read(), 'B')
        with self.assertRaises(BufferEmptyException):
            buf.read()


if __name__ == '__main__':
    unittest.main()