PythonSnips/datastructures/circular_buffer/test_circular_buffer.py at 33a26e07f251776992908722871fc842259dd63f · BrianLusina/PythonSnips · GitHub

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import unittest

from datastructures.circular_buffer import (
    BufferEmptyException,
    BufferFullException,
    CircularBuffer,
)


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("1", buf.read())
        self.assertEqual("2", buf.read())
        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("1", buf.read())
        buf.write("3")
        self.assertEqual("2", buf.read())

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

    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("3", buf.read())

    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("2", buf.read())
        self.assertEqual("A", buf.read())
        with self.assertRaises(BufferEmptyException):
            buf.read()

    def test_overwrite_non_full_buffer(self):
        buf = CircularBuffer(2)
        buf.overwrite("1")
        buf.overwrite("2")
        self.assertEqual("1", buf.read())
        self.assertEqual("2", buf.read())
        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("6", buf.read())
        self.assertEqual("7", buf.read())
        self.assertEqual("8", buf.read())
        self.assertEqual("A", buf.read())
        self.assertEqual("B", buf.read())
        with self.assertRaises(BufferEmptyException):
            buf.read()


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