def test_block_capacity_returns_the_byte_capacity_left_in_the_block():
block = FileBlock(DATA_BLOCK)
expected = 253
block.append(0x01)
block.append(0x02)
actual = block.capacity()
assert actual == expected
def test_file_block_creates_a_new_minimal_cas_block_byte_array():
block = FileBlock(NAME_FILE_BLOCK)
expected = [0x3c, 0x00, 0x00, 0x00]
actual = block.seal_block()
assert actual == expected
def test_block_seal_closes_the_block_with_a_checksum():
block = FileBlock(NAME_FILE_BLOCK)
expected = [
0x3c, 0x00, 0x0f, 0x54, 0x45, 0x45, 0x44, 0x20, 0x31, 0x2e, 0x34, 0x00,
0x00, 0x00, 0x00, 0x00, 0x7c, 0xaf, 0x0f
]
filename = list("TEED 1.4")
for x in range(8):
block.append(ord(filename[x]))
block.append(BASIC_FILE_IDENTIFIER)
block.append(BINARY_FILE_FLAG)
block.append(CONTINUOUS_FILE)
block.append(0)
block.append(0)
block.append(0x7c)
block.append(0xaf)
actual = block.seal_block()
assert actual == expected
def test_block_append_raises_exception_if_non_byte_value_supplied(test_input):
block = FileBlock(DATA_BLOCK)
with pytest.raises(ValueError):
block.append(test_input)
def test_block_append_raises_exception_if_capacity_exceeded():
block = FileBlock(DATA_BLOCK)
for x in range(255):
block.append(x)
with pytest.raises(ValueError):
block.append(1)
def test_block_append_adds_a_byte_to_the_block():
block = FileBlock(DATA_BLOCK)
expected = [0x3c, 0x01, 0x01, 0x01, 0x03]
block.append(0x01)
actual = block.seal_block()
assert actual == expected
def build_file(self, filename, data, header_length=DEFAULT_LEADER_SIZE):
self.leader_length = header_length
result = self.build_header(filename)
loop = len(data) > 0
block = FileBlock(DATA_BLOCK)
while loop:
if block.capacity() == 0:
result += block.seal_block()
result.append(LEADER)
result.append(LEADER)
block = FileBlock(DATA_BLOCK)
block.append(data.pop(0))
loop = len(data) > 0
result += block.seal_block()
result.append(LEADER)
result.append(LEADER)
block = FileBlock(END_OF_FILE_BLOCK)
result += block.seal_block()
result.append(LEADER)
return bytearray(result)
def build_header(self, filename):
result = []
filename_list = list(filename)
del filename_list[FILENAME_LENGTH:]
while len(filename_list) < FILENAME_LENGTH:
filename_list.append(" ")
for x in range(self.leader_length):
result.append(LEADER)
block = FileBlock(NAME_FILE_BLOCK)
for x in range(FILENAME_LENGTH):
block.append(ord(filename_list[x]))
block.append(BASIC_FILE_IDENTIFIER)
block.append(BINARY_FILE_FLAG)
block.append(CONTINUOUS_FILE)
block.append(0)
block.append(0)
block.append(0x7c)
block.append(0xaf)
result += block.seal_block()
for x in range(self.leader_length):
result.append(LEADER)
return result