1import unittest
2from test import test_support as support
3
4import io # C implementation.
5import _pyio as pyio # Python implementation.
6
7# Simple test to ensure that optimizations in the IO library deliver the
8# expected results.  For best testing, run this under a debug-build Python too
9# (to exercise asserts in the C code).
10
11lengths = list(range(1, 257)) + [512, 1000, 1024, 2048, 4096, 8192, 10000,
12                                 16384, 32768, 65536, 1000000]
13
14class BufferSizeTest(unittest.TestCase):
15    def try_one(self, s):
16        # Write s + "\n" + s to file, then open it and ensure that successive
17        # .readline()s deliver what we wrote.
18
19        # Ensure we can open TESTFN for writing.
20        support.unlink(support.TESTFN)
21
22        # Since C doesn't guarantee we can write/read arbitrary bytes in text
23        # files, use binary mode.
24        f = self.open(support.TESTFN, "wb")
25        try:
26            # write once with \n and once without
27            f.write(s)
28            f.write(b"\n")
29            f.write(s)
30            f.close()
31            f = open(support.TESTFN, "rb")
32            line = f.readline()
33            self.assertEqual(line, s + b"\n")
34            line = f.readline()
35            self.assertEqual(line, s)
36            line = f.readline()
37            self.assertFalse(line) # Must be at EOF
38            f.close()
39        finally:
40            support.unlink(support.TESTFN)
41
42    def drive_one(self, pattern):
43        for length in lengths:
44            # Repeat string 'pattern' as often as needed to reach total length
45            # 'length'.  Then call try_one with that string, a string one larger
46            # than that, and a string one smaller than that.  Try this with all
47            # small sizes and various powers of 2, so we exercise all likely
48            # stdio buffer sizes, and "off by one" errors on both sides.
49            q, r = divmod(length, len(pattern))
50            teststring = pattern * q + pattern[:r]
51            self.assertEqual(len(teststring), length)
52            self.try_one(teststring)
53            self.try_one(teststring + b"x")
54            self.try_one(teststring[:-1])
55
56    def test_primepat(self):
57        # A pattern with prime length, to avoid simple relationships with
58        # stdio buffer sizes.
59        self.drive_one(b"1234567890\00\01\02\03\04\05\06")
60
61    def test_nullpat(self):
62        self.drive_one(bytes(1000))
63
64
65class CBufferSizeTest(BufferSizeTest):
66    open = io.open
67
68class PyBufferSizeTest(BufferSizeTest):
69    open = staticmethod(pyio.open)
70
71class BuiltinBufferSizeTest(BufferSizeTest):
72    open = open
73
74
75def test_main():
76    support.run_unittest(CBufferSizeTest, PyBufferSizeTest, BuiltinBufferSizeTest)
77
78if __name__ == "__main__":
79    test_main()
80