diff options
Diffstat (limited to 'Lib/test/test_io.py')
| -rw-r--r-- | Lib/test/test_io.py | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py index aa1679b..c584b92 100644 --- a/Lib/test/test_io.py +++ b/Lib/test/test_io.py @@ -52,12 +52,14 @@ class MockRawIO: self._read_stack = list(read_stack) self._write_stack = [] self._reads = 0 + self._extraneous_reads = 0 def read(self, n=None): self._reads += 1 try: return self._read_stack.pop(0) except: + self._extraneous_reads += 1 return b"" def write(self, b): @@ -88,6 +90,7 @@ class MockRawIO: try: data = self._read_stack[0] except IndexError: + self._extraneous_reads += 1 return 0 if data is None: del self._read_stack[0] @@ -824,6 +827,27 @@ class BufferedReaderTest(unittest.TestCase, CommonBufferedTests): self.assertRaises(IOError, bufio.seek, 0) self.assertRaises(IOError, bufio.tell) + def test_no_extraneous_read(self): + # Issue #9550; when the raw IO object has satisfied the read request, + # we should not issue any additional reads, otherwise it may block + # (e.g. socket). + bufsize = 16 + for n in (2, bufsize - 1, bufsize, bufsize + 1, bufsize * 2): + rawio = self.MockRawIO([b"x" * n]) + bufio = self.tp(rawio, bufsize) + self.assertEqual(bufio.read(n), b"x" * n) + # Simple case: one raw read is enough to satisfy the request. + self.assertEqual(rawio._extraneous_reads, 0, + "failed for {}: {} != 0".format(n, rawio._extraneous_reads)) + # A more complex case where two raw reads are needed to satisfy + # the request. + rawio = self.MockRawIO([b"x" * (n - 1), b"x"]) + bufio = self.tp(rawio, bufsize) + self.assertEqual(bufio.read(n), b"x" * n) + self.assertEqual(rawio._extraneous_reads, 0, + "failed for {}: {} != 0".format(n, rawio._extraneous_reads)) + + class CBufferedReaderTest(BufferedReaderTest): tp = io.BufferedReader |