implement a detach() method for BufferedIOBase and TextIOBase #5883
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index a8c878e..1a525dc 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -526,6 +526,12 @@
class CommonBufferedTests:
# Tests common to BufferedReader, BufferedWriter and BufferedRandom
+ def test_detach(self):
+ raw = self.MockRawIO()
+ buf = self.tp(raw)
+ self.assertIs(buf.detach(), raw)
+ self.assertRaises(ValueError, buf.detach)
+
def test_fileno(self):
rawio = self.MockRawIO()
bufio = self.tp(rawio)
@@ -811,6 +817,14 @@
bufio.flush()
self.assertEquals(b"".join(rawio._write_stack), b"abcghi")
+ def test_detach_flush(self):
+ raw = self.MockRawIO()
+ buf = self.tp(raw)
+ buf.write(b"howdy!")
+ self.assertFalse(raw._write_stack)
+ buf.detach()
+ self.assertEqual(raw._write_stack, [b"howdy!"])
+
def test_write(self):
# Write to the buffered IO but don't overflow the buffer.
writer = self.MockRawIO()
@@ -1052,6 +1066,10 @@
pair = self.tp(self.MockRawIO(), self.MockRawIO())
self.assertFalse(pair.closed)
+ def test_detach(self):
+ pair = self.tp(self.MockRawIO(), self.MockRawIO())
+ self.assertRaises(self.UnsupportedOperation, pair.detach)
+
def test_constructor_max_buffer_size_deprecation(self):
with support.check_warnings() as w:
warnings.simplefilter("always", DeprecationWarning)
@@ -1480,6 +1498,19 @@
self.assertRaises(TypeError, t.__init__, b, newline=42)
self.assertRaises(ValueError, t.__init__, b, newline='xyzzy')
+ def test_detach(self):
+ r = self.BytesIO()
+ b = self.BufferedWriter(r)
+ t = self.TextIOWrapper(b)
+ self.assertIs(t.detach(), b)
+
+ t = self.TextIOWrapper(b, encoding="ascii")
+ t.write("howdy")
+ self.assertFalse(r.getvalue())
+ t.detach()
+ self.assertEqual(r.getvalue(), b"howdy")
+ self.assertRaises(ValueError, t.detach)
+
def test_repr(self):
raw = self.BytesIO("hello".encode("utf-8"))
b = self.BufferedReader(raw)
diff --git a/Lib/test/test_memoryio.py b/Lib/test/test_memoryio.py
index ad04613..d94d9dd 100644
--- a/Lib/test/test_memoryio.py
+++ b/Lib/test/test_memoryio.py
@@ -57,6 +57,10 @@
class MemoryTestMixin:
+ def test_detach(self):
+ buf = self.ioclass()
+ self.assertRaises(self.UnsupportedOperation, buf.detach)
+
def write_ops(self, f, t):
self.assertEqual(f.write(t("blah.")), 5)
self.assertEqual(f.seek(0), 0)
@@ -336,6 +340,9 @@
class PyBytesIOTest(MemoryTestMixin, MemorySeekTestMixin, unittest.TestCase):
+
+ UnsupportedOperation = pyio.UnsupportedOperation
+
@staticmethod
def buftype(s):
return s.encode("ascii")
@@ -413,6 +420,7 @@
class PyStringIOTest(MemoryTestMixin, MemorySeekTestMixin, unittest.TestCase):
buftype = str
ioclass = pyio.StringIO
+ UnsupportedOperation = pyio.UnsupportedOperation
EOF = ""
# TextIO-specific behaviour.
@@ -518,9 +526,11 @@
class CBytesIOTest(PyBytesIOTest):
ioclass = io.BytesIO
+ UnsupportedOperation = io.UnsupportedOperation
class CStringIOTest(PyStringIOTest):
ioclass = io.StringIO
+ UnsupportedOperation = io.UnsupportedOperation
# XXX: For the Python version of io.StringIO, this is highly
# dependent on the encoding used for the underlying buffer.