comparers.py
1.82 KB
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"""
Digress comparers.
"""
from digress.errors import ComparisonError
import os
from itertools import imap, izip
def compare_direct(value_a, value_b):
if value_a != value_b:
raise ComparisonError("%s is not %s" % (value_a, value_b))
def compare_pass(value_a, value_b):
"""
Always true, as long as the test is passed.
"""
def compare_tolerance(tolerance):
def _compare_tolerance(value_a, value_b):
if abs(value_a - value_b) > tolerance:
raise ComparisonError("%s is not %s (tolerance: %s)" % (
value_a,
value_b,
tolerance
))
return _compare_tolerance
def compare_files(file_a, file_b):
size_a = os.path.getsize(file_a)
size_b = os.path.getsize(file_b)
print file_a, file_b
if size_a != size_b:
raise ComparisonError("%s is not the same size as %s" % (
file_a,
file_b
))
BUFFER_SIZE = 8196
offset = 0
with open(file_a) as f_a:
with open(file_b) as f_b:
for chunk_a, chunk_b in izip(
imap(
lambda i: f_a.read(BUFFER_SIZE),
xrange(size_a // BUFFER_SIZE + 1)
),
imap(
lambda i: f_b.read(BUFFER_SIZE),
xrange(size_b // BUFFER_SIZE + 1)
)
):
chunk_size = len(chunk_a)
if chunk_a != chunk_b:
for i in xrange(chunk_size):
if chunk_a[i] != chunk_b[i]:
raise ComparisonError("%s differs from %s at offset %d" % (
file_a,
file_b,
offset + i
))
offset += chunk_size