test_file.py

import sys
import os
import unittest
from array import array
from weakref import proxy

from test.test_support import TESTFN, findfile, run_unittest
from UserList import UserList

class AutoFileTests(unittest.TestCase):
    # file tests for which a test file is automatically set up

    def setUp(self):
        self.f = open(TESTFN, 'wb')

    def tearDown(self):
        if self.f:
            self.f.close()
        os.remove(TESTFN)

    def testWeakRefs(self):
        # verify weak references
        p = proxy(self.f)
        p.write('teststring')
        self.assertEquals(self.f.tell(), p.tell())
        self.f.close()
        self.f = None
        self.assertRaises(ReferenceError, getattr, p, 'tell')

    def testAttributes(self):
        # verify expected attributes exist
        f = self.f
        softspace = f.softspace
        f.name     # merely shouldn't blow up
        f.mode     # ditto
        f.closed   # ditto

        # verify softspace is writable
        f.softspace = softspace    # merely shouldn't blow up

        # verify the others aren't
        for attr in 'name', 'mode', 'closed':
            self.assertRaises((AttributeError, TypeError), setattr, f, attr, 'oops')

    def testReadinto(self):
        # verify readinto
        self.f.write('12')
        self.f.close()
        a = array('c', 'x'*10)
        self.f = open(TESTFN, 'rb')
        n = self.f.readinto(a)
        self.assertEquals('12', a.tostring()[:n])

    def testWritelinesUserList(self):
        # verify writelines with instance sequence
        l = UserList(['1', '2'])
        self.f.writelines(l)
        self.f.close()
        self.f = open(TESTFN, 'rb')
        buf = self.f.read()
        self.assertEquals(buf, '12')

    def testWritelinesIntegers(self):
        # verify writelines with integers
        self.assertRaises(TypeError, self.f.writelines, [1, 2, 3])

    def testWritelinesIntegersUserList(self):
        # verify writelines with integers in UserList
        l = UserList([1,2,3])
        self.assertRaises(TypeError, self.f.writelines, l)

    def testWritelinesNonString(self):
        # verify writelines with non-string object
        class NonString:
            pass

        self.assertRaises(TypeError, self.f.writelines,
                          [NonString(), NonString()])

    def testRepr(self):
        # verify repr works
        self.assert_(repr(self.f).startswith("<open file '" + TESTFN))

    def testErrors(self):
        f = self.f
        self.assertEquals(f.name, TESTFN)
        self.assert_(not f.isatty())
        self.assert_(not f.closed)

        self.assertRaises(TypeError, f.readinto, "")
        f.close()
        self.assert_(f.closed)

    def testMethods(self):
        methods = ['fileno', 'flush', 'isatty', 'next', 'read', 'readinto',
                   'readline', 'readlines', 'seek', 'tell', 'truncate',
                   'write', 'xreadlines', '__iter__']
        if sys.platform.startswith('atheos'):
            methods.remove('truncate')

        # __exit__ should close the file
        self.f.__exit__(None, None, None)
        self.assert_(self.f.closed)

        for methodname in methods:
            method = getattr(self.f, methodname)
            # should raise on closed file
            self.assertRaises(ValueError, method)
        self.assertRaises(ValueError, self.f.writelines, [])

        # file is closed, __exit__ shouldn't do anything
        self.assertEquals(self.f.__exit__(None, None, None), None)
        # it must also return None if an exception was given
        try:
            1/0
        except:
            self.assertEquals(self.f.__exit__(*sys.exc_info()), None)


class OtherFileTests(unittest.TestCase):

    def testModeStrings(self):
        # check invalid mode strings
        for mode in ("", "aU", "wU+"):
            try:
                f = open(TESTFN, mode)
            except ValueError:
                pass
            else:
                f.close()
                self.fail('%r is an invalid file mode' % mode)

    def testStdin(self):
        # This causes the interpreter to exit on OSF1 v5.1.
        if sys.platform != 'osf1V5':
            self.assertRaises(IOError, sys.stdin.seek, -1)
        else:
            print >>sys.__stdout__, (
                '  Skipping sys.stdin.seek(-1), it may crash the interpreter.'
                ' Test manually.')
        self.assertRaises(IOError, sys.stdin.truncate)

    def testUnicodeOpen(self):
        # verify repr works for unicode too
        f = open(unicode(TESTFN), "w")
        self.assert_(repr(f).startswith("<open file u'" + TESTFN))
        f.close()
        os.unlink(TESTFN)

    def testBadModeArgument(self):
        # verify that we get a sensible error message for bad mode argument
        bad_mode = "qwerty"
        try:
            f = open(TESTFN, bad_mode)
        except ValueError, msg:
            if msg[0] != 0:
                s = str(msg)
                if s.find(TESTFN) != -1 or s.find(bad_mode) == -1:
                    self.fail("bad error message for invalid mode: %s" % s)
            # if msg[0] == 0, we're probably on Windows where there may be
            # no obvious way to discover why open() failed.
        else:
            f.close()
            self.fail("no error for invalid mode: %s" % bad_mode)

    def testSetBufferSize(self):
        # make sure that explicitly setting the buffer size doesn't cause
        # misbehaviour especially with repeated close() calls
        for s in (-1, 0, 1, 512):
            try:
                f = open(TESTFN, 'w', s)
                f.write(str(s))
                f.close()
                f.close()
                f = open(TESTFN, 'r', s)
                d = int(f.read())
                f.close()
                f.close()
            except IOError, msg:
                self.fail('error setting buffer size %d: %s' % (s, str(msg)))
            self.assertEquals(d, s)

    def testTruncateOnWindows(self):
        os.unlink(TESTFN)

        def bug801631():
            # SF bug <http://www.python.org/sf/801631>
            # "file.truncate fault on windows"
            f = open(TESTFN, 'wb')
            f.write('12345678901')   # 11 bytes
            f.close()

            f = open(TESTFN,'rb+')
            data = f.read(5)
            if data != '12345':
                self.fail("Read on file opened for update failed %r" % data)
            if f.tell() != 5:
                self.fail("File pos after read wrong %d" % f.tell())

            f.truncate()
            if f.tell() != 5:
                self.fail("File pos after ftruncate wrong %d" % f.tell())

            f.close()
            size = os.path.getsize(TESTFN)
            if size != 5:
                self.fail("File size after ftruncate wrong %d" % size)

        try:
            bug801631()
        finally:
            os.unlink(TESTFN)

    def testIteration(self):
        # Test the complex interaction when mixing file-iteration and the
        # various read* methods. Ostensibly, the mixture could just be tested
        # to work when it should work according to the Python language,
        # instead of fail when it should fail according to the current CPython
        # implementation.  People don't always program Python the way they
        # should, though, and the implemenation might change in subtle ways,
        # so we explicitly test for errors, too; the test will just have to
        # be updated when the implementation changes.
        dataoffset = 16384
        filler = "ham\n"
        assert not dataoffset % len(filler), \
            "dataoffset must be multiple of len(filler)"
        nchunks = dataoffset // len(filler)
        testlines = [
            "spam, spam and eggs\n",
            "eggs, spam, ham and spam\n",
            "saussages, spam, spam and eggs\n",
            "spam, ham, spam and eggs\n",
            "spam, spam, spam, spam, spam, ham, spam\n",
            "wonderful spaaaaaam.\n"
        ]
        methods = [("readline", ()), ("read", ()), ("readlines", ()),
                   ("readinto", (array("c", " "*100),))]

        try:
            # Prepare the testfile
            bag = open(TESTFN, "w")
            bag.write(filler * nchunks)
            bag.writelines(testlines)
            bag.close()
            # Test for appropriate errors mixing read* and iteration
            for methodname, args in methods:
                f = open(TESTFN)
                if f.next() != filler:
                    self.fail, "Broken testfile"
                meth = getattr(f, methodname)
                try:
                    meth(*args)
                except ValueError:
                    pass
                else:
                    self.fail("%s%r after next() didn't raise ValueError" %
                                     (methodname, args))
                f.close()

            # Test to see if harmless (by accident) mixing of read* and
            # iteration still works. This depends on the size of the internal
            # iteration buffer (currently 8192,) but we can test it in a
            # flexible manner.  Each line in the bag o' ham is 4 bytes
            # ("h", "a", "m", "\n"), so 4096 lines of that should get us
            # exactly on the buffer boundary for any power-of-2 buffersize
            # between 4 and 16384 (inclusive).
            f = open(TESTFN)
            for i in range(nchunks):
                f.next()
            testline = testlines.pop(0)
            try:
                line = f.readline()
            except ValueError:
                self.fail("readline() after next() with supposedly empty "
                          "iteration-buffer failed anyway")
            if line != testline:
                self.fail("readline() after next() with empty buffer "
                          "failed. Got %r, expected %r" % (line, testline))
            testline = testlines.pop(0)
            buf = array("c", "\x00" * len(testline))
            try:
                f.readinto(buf)
            except ValueError:
                self.fail("readinto() after next() with supposedly empty "
                          "iteration-buffer failed anyway")
            line = buf.tostring()
            if line != testline:
                self.fail("readinto() after next() with empty buffer "
                          "failed. Got %r, expected %r" % (line, testline))

            testline = testlines.pop(0)
            try:
                line = f.read(len(testline))
            except ValueError:
                self.fail("read() after next() with supposedly empty "
                          "iteration-buffer failed anyway")
            if line != testline:
                self.fail("read() after next() with empty buffer "
                          "failed. Got %r, expected %r" % (line, testline))
            try:
                lines = f.readlines()
            except ValueError:
                self.fail("readlines() after next() with supposedly empty "
                          "iteration-buffer failed anyway")
            if lines != testlines:
                self.fail("readlines() after next() with empty buffer "
                          "failed. Got %r, expected %r" % (line, testline))
            # Reading after iteration hit EOF shouldn't hurt either
            f = open(TESTFN)
            try:
                for line in f:
                    pass
                try:
                    f.readline()
                    f.readinto(buf)
                    f.read()
                    f.readlines()
                except ValueError:
                    self.fail("read* failed after next() consumed file")
            finally:
                f.close()
        finally:
            os.unlink(TESTFN)

class FileSubclassTests(unittest.TestCase):

    def testExit(self):
        # test that exiting with context calls subclass' close
        class C(file):
            def __init__(self, *args):
                self.subclass_closed = False
                file.__init__(self, *args)
            def close(self):
                self.subclass_closed = True
                file.close(self)

        with C(TESTFN, 'w') as f:
            pass
        self.failUnless(f.subclass_closed)


def test_main():
    # Historically, these tests have been sloppy about removing TESTFN.
    # So get rid of it no matter what.
    try:
        run_unittest(AutoFileTests, OtherFileTests, FileSubclassTests)
    finally:
        if os.path.exists(TESTFN):
            os.unlink(TESTFN)

if __name__ == '__main__':
    test_main()