cpython/Lib/test/test_io.py

"""Unit tests for io.py."""

import unittest
from test import test_support

import io

class MockIO(io.RawIOBase):
    def __init__(self, readStack=()):
        self._readStack = list(readStack)
        self._writeStack = []

    def read(self, n=None):
        try:
            return self._readStack.pop(0)
        except:
            return io.EOF

    def write(self, b):
        self._writeStack.append(b)
        return len(b)

    def writable(self):
        return True

    def fileno(self):
        return 42

    def readable(self):
        return True

    def seekable(self):
        return True

    def seek(self, pos, whence):
        pass

    def tell(self):
        return 42

class MockNonBlockWriterIO(io.RawIOBase):
    def __init__(self, blockingScript):
        self.bs = list(blockingScript)
        self._write_stack = []
    def write(self, b):
        self._write_stack.append(b)
        n = self.bs.pop(0)
        if (n < 0):
            raise io.BlockingIO(0, "test blocking", -n)
        else:
            return n
    def writable(self):
        return True

class IOTest(unittest.TestCase):

    def tearDown(self):
        test_support.unlink(test_support.TESTFN)

    def write_ops(self, f):
        f.write(b"blah.")
        f.seek(0)
        f.write(b"Hello.")
        self.assertEqual(f.tell(), 6)
        f.seek(-1, 1)
        self.assertEqual(f.tell(), 5)
        f.write(" world\n\n\n")
        f.seek(0)
        f.write("h")
        f.seek(-2, 2)
        f.truncate()

    def read_ops(self, f):
        data = f.read(5)
        self.assertEqual(data, b"hello")
        n = f.readinto(data)
        self.assertEqual(n, 5)
        self.assertEqual(data, b" worl")
        n = f.readinto(data)
        self.assertEqual(n, 2)
        self.assertEqual(len(data), 5)
        self.assertEqual(data[:2], b"d\n")
        f.seek(0)
        self.assertEqual(f.read(20), b"hello world\n")
        f.seek(-6, 2)
        self.assertEqual(f.read(5), b"world")
        f.seek(-6, 1)
        self.assertEqual(f.read(5), b" worl")
        self.assertEqual(f.tell(), 10)

    def test_raw_file_io(self):
        f = io.open(test_support.TESTFN, "wb", buffering=0)
        self.assertEqual(f.readable(), False)
        self.assertEqual(f.writable(), True)
        self.assertEqual(f.seekable(), True)
        self.write_ops(f)
        f.close()
        f = io.open(test_support.TESTFN, "rb", buffering=0)
        self.assertEqual(f.readable(), True)
        self.assertEqual(f.writable(), False)
        self.assertEqual(f.seekable(), True)
        self.read_ops(f)
        f.close()

    def test_raw_bytes_io(self):
        f = io.BytesIO()
        self.write_ops(f)
        data = f.getvalue()
        self.assertEqual(data, b"hello world\n")
        f = io.BytesIO(data)
        self.read_ops(f)

class BytesIOTest(unittest.TestCase):
    def testInit(self):
        buf = b"1234567890"
        bytesIo = io.BytesIO(buf)

    def testRead(self):
        buf = b"1234567890"
        bytesIo = io.BytesIO(buf)

        self.assertEquals(buf[:1], bytesIo.read(1))
        self.assertEquals(buf[1:5], bytesIo.read(4))
        self.assertEquals(buf[5:], bytesIo.read(900))
        self.assertEquals(io.EOF, bytesIo.read())

    def testReadNoArgs(self):
        buf = b"1234567890"
        bytesIo = io.BytesIO(buf)

        self.assertEquals(buf, bytesIo.read())
        self.assertEquals(io.EOF, bytesIo.read())

    def testSeek(self):
        buf = b"1234567890"
        bytesIo = io.BytesIO(buf)

        bytesIo.read(5)
        bytesIo.seek(0)
        self.assertEquals(buf, bytesIo.read())

        bytesIo.seek(3)
        self.assertEquals(buf[3:], bytesIo.read())

    def testTell(self):
        buf = b"1234567890"
        bytesIo = io.BytesIO(buf)

        self.assertEquals(0, bytesIo.tell())
        bytesIo.seek(5)
        self.assertEquals(5, bytesIo.tell())
        bytesIo.seek(10000)
        self.assertEquals(10000, bytesIo.tell())

class BufferedReaderTest(unittest.TestCase):
    def testRead(self):
        rawIo = MockIO((b"abc", b"d", b"efg"))
        bufIo = io.BufferedReader(rawIo)

        self.assertEquals(b"abcdef", bufIo.read(6))

    def testReadNonBlocking(self):
        # Inject some None's in there to simulate EWOULDBLOCK
        rawIo = MockIO((b"abc", b"d", None, b"efg", None, None))
        bufIo = io.BufferedReader(rawIo)

        self.assertEquals(b"abcd", bufIo.read(6))
        self.assertEquals(b"e", bufIo.read(1))
        self.assertEquals(b"fg", bufIo.read())
        self.assert_(None is bufIo.read())
        self.assertEquals(io.EOF, bufIo.read())

    def testReadToEof(self):
        rawIo = MockIO((b"abc", b"d", b"efg"))
        bufIo = io.BufferedReader(rawIo)

        self.assertEquals(b"abcdefg", bufIo.read(9000))

    def testReadNoArgs(self):
        rawIo = MockIO((b"abc", b"d", b"efg"))
        bufIo = io.BufferedReader(rawIo)

        self.assertEquals(b"abcdefg", bufIo.read())

    def testFileno(self):
        rawIo = MockIO((b"abc", b"d", b"efg"))
        bufIo = io.BufferedReader(rawIo)

        self.assertEquals(42, bufIo.fileno())

    def testFilenoNoFileno(self):
        # XXX will we always have fileno() function? If so, kill
        # this test. Else, write it.
        pass

class BufferedWriterTest(unittest.TestCase):
    def testWrite(self):
        # Write to the buffered IO but don't overflow the buffer.
        writer = MockIO()
        bufIo = io.BufferedWriter(writer, 8)

        bufIo.write(b"abc")

        self.assertFalse(writer._writeStack)

    def testWriteOverflow(self):
        writer = MockIO()
        bufIo = io.BufferedWriter(writer, 8)

        bufIo.write(b"abc")
        bufIo.write(b"defghijkl")

        self.assertEquals(b"abcdefghijkl", writer._writeStack[0])

    def testWriteNonBlocking(self):
        raw = MockNonBlockWriterIO((9, 2, 22, -6, 10, 12, 12))
        bufIo = io.BufferedWriter(raw, 8, 16)

        bufIo.write(b"asdf")
        bufIo.write(b"asdfa")
        self.assertEquals(b"asdfasdfa", raw._write_stack[0])

        bufIo.write(b"asdfasdfasdf")
        self.assertEquals(b"asdfasdfasdf", raw._write_stack[1])
        bufIo.write(b"asdfasdfasdf")
        self.assertEquals(b"dfasdfasdf", raw._write_stack[2])
        self.assertEquals(b"asdfasdfasdf", raw._write_stack[3])

        bufIo.write(b"asdfasdfasdf")

        # XXX I don't like this test. It relies too heavily on how the algorithm
        # actually works, which we might change. Refactor later.

    def testFileno(self):
        rawIo = MockIO((b"abc", b"d", b"efg"))
        bufIo = io.BufferedWriter(rawIo)

        self.assertEquals(42, bufIo.fileno())

    def testFlush(self):
        writer = MockIO()
        bufIo = io.BufferedWriter(writer, 8)

        bufIo.write(b"abc")
        bufIo.flush()

        self.assertEquals(b"abc", writer._writeStack[0])

class BufferedRWPairTest(unittest.TestCase):
    def testRWPair(self):
        r = MockIO(())
        w = MockIO()
        pair = io.BufferedRWPair(r, w)

        # XXX need implementation

class BufferedRandom(unittest.TestCase):
    def testReadAndWrite(self):
        raw = MockIO((b"asdf", b"ghjk"))
        rw = io.BufferedRandom(raw, 8, 12)

        self.assertEqual(b"as", rw.read(2))
        rw.write(b"ddd")
        rw.write(b"eee")
        self.assertFalse(raw._writeStack) # Buffer writes
        self.assertEqual(b"ghjk", rw.read()) # This read forces write flush
        self.assertEquals(b"dddeee", raw._writeStack[0])

    def testSeekAndTell(self):
        raw = io.BytesIO(b"asdfghjkl")
        rw = io.BufferedRandom(raw)

        self.assertEquals(b"as", rw.read(2))
        self.assertEquals(2, rw.tell())
        rw.seek(0, 0)
        self.assertEquals(b"asdf", rw.read(4))

        rw.write(b"asdf")
        rw.seek(0, 0)
        self.assertEquals(b"asdfasdfl", rw.read())
        self.assertEquals(9, rw.tell())
        rw.seek(-4, 2)
        self.assertEquals(5, rw.tell())
        rw.seek(2, 1)
        self.assertEquals(7, rw.tell())
        self.assertEquals(b"fl", rw.read(11))

# XXX Tests for open()

def test_main():
    test_support.run_unittest(IOTest, BytesIOTest, BufferedReaderTest,
                              BufferedWriterTest, BufferedRWPairTest,
                              BufferedRandom)

if __name__ == "__main__":
    test_main()