Lib/test/test_fileinput.py

'''
Tests for fileinput module.
Nick Mathewson
'''
import os
import sys
import re
import fileinput
import collections
import gzip
import bz2
import types
import codecs
import unittest

from io import StringIO
from fileinput import FileInput, hook_encoded

from test.support import verbose, TESTFN, run_unittest
from test.support import unlink as safe_unlink


# The fileinput module has 2 interfaces: the FileInput class which does
# all the work, and a few functions (input, etc.) that use a global _state
# variable.

# Write lines (a list of lines) to temp file number i, and return the
# temp file's name.
def writeTmp(i, lines, mode='w'):  # opening in text mode is the default
    name = TESTFN + str(i)
    f = open(name, mode)
    for line in lines:
        f.write(line)
    f.close()
    return name

def remove_tempfiles(*names):
    for name in names:
        if name:
            safe_unlink(name)

class BufferSizesTests(unittest.TestCase):
    def test_buffer_sizes(self):
        # First, run the tests with default and teeny buffer size.
        for round, bs in (0, 0), (1, 30):
            t1 = t2 = t3 = t4 = None
            try:
                t1 = writeTmp(1, ["Line %s of file 1\n" % (i+1) for i in range(15)])
                t2 = writeTmp(2, ["Line %s of file 2\n" % (i+1) for i in range(10)])
                t3 = writeTmp(3, ["Line %s of file 3\n" % (i+1) for i in range(5)])
                t4 = writeTmp(4, ["Line %s of file 4\n" % (i+1) for i in range(1)])
                self.buffer_size_test(t1, t2, t3, t4, bs, round)
            finally:
                remove_tempfiles(t1, t2, t3, t4)

    def buffer_size_test(self, t1, t2, t3, t4, bs=0, round=0):
        pat = re.compile(r'LINE (\d+) OF FILE (\d+)')

        start = 1 + round*6
        if verbose:
            print('%s. Simple iteration (bs=%s)' % (start+0, bs))
        fi = FileInput(files=(t1, t2, t3, t4), bufsize=bs)
        lines = list(fi)
        fi.close()
        self.assertEqual(len(lines), 31)
        self.assertEqual(lines[4], 'Line 5 of file 1\n')
        self.assertEqual(lines[30], 'Line 1 of file 4\n')
        self.assertEqual(fi.lineno(), 31)
        self.assertEqual(fi.filename(), t4)

        if verbose:
            print('%s. Status variables (bs=%s)' % (start+1, bs))
        fi = FileInput(files=(t1, t2, t3, t4), bufsize=bs)
        s = "x"
        while s and s != 'Line 6 of file 2\n':
            s = fi.readline()
        self.assertEqual(fi.filename(), t2)
        self.assertEqual(fi.lineno(), 21)
        self.assertEqual(fi.filelineno(), 6)
        self.assertFalse(fi.isfirstline())
        self.assertFalse(fi.isstdin())

        if verbose:
            print('%s. Nextfile (bs=%s)' % (start+2, bs))
        fi.nextfile()
        self.assertEqual(fi.readline(), 'Line 1 of file 3\n')
        self.assertEqual(fi.lineno(), 22)
        fi.close()

        if verbose:
            print('%s. Stdin (bs=%s)' % (start+3, bs))
        fi = FileInput(files=(t1, t2, t3, t4, '-'), bufsize=bs)
        savestdin = sys.stdin
        try:
            sys.stdin = StringIO("Line 1 of stdin\nLine 2 of stdin\n")
            lines = list(fi)
            self.assertEqual(len(lines), 33)
            self.assertEqual(lines[32], 'Line 2 of stdin\n')
            self.assertEqual(fi.filename(), '<stdin>')
            fi.nextfile()
        finally:
            sys.stdin = savestdin

        if verbose:
            print('%s. Boundary conditions (bs=%s)' % (start+4, bs))
        fi = FileInput(files=(t1, t2, t3, t4), bufsize=bs)
        self.assertEqual(fi.lineno(), 0)
        self.assertEqual(fi.filename(), None)
        fi.nextfile()
        self.assertEqual(fi.lineno(), 0)
        self.assertEqual(fi.filename(), None)

        if verbose:
            print('%s. Inplace (bs=%s)' % (start+5, bs))
        savestdout = sys.stdout
        try:
            fi = FileInput(files=(t1, t2, t3, t4), inplace=1, bufsize=bs)
            for line in fi:
                line = line[:-1].upper()
                print(line)
            fi.close()
        finally:
            sys.stdout = savestdout

        fi = FileInput(files=(t1, t2, t3, t4), bufsize=bs)
        for line in fi:
            self.assertEqual(line[-1], '\n')
            m = pat.match(line[:-1])
            self.assertNotEqual(m, None)
            self.assertEqual(int(m.group(1)), fi.filelineno())
        fi.close()

class UnconditionallyRaise:
    def __init__(self, exception_type):
        self.exception_type = exception_type
        self.invoked = False
    def __call__(self, *args, **kwargs):
        self.invoked = True
        raise self.exception_type()

class FileInputTests(unittest.TestCase):

    def test_zero_byte_files(self):
        t1 = t2 = t3 = t4 = None
        try:
            t1 = writeTmp(1, [""])
            t2 = writeTmp(2, [""])
            t3 = writeTmp(3, ["The only line there is.\n"])
            t4 = writeTmp(4, [""])
            fi = FileInput(files=(t1, t2, t3, t4))

            line = fi.readline()
            self.assertEqual(line, 'The only line there is.\n')
            self.assertEqual(fi.lineno(), 1)
            self.assertEqual(fi.filelineno(), 1)
            self.assertEqual(fi.filename(), t3)

            line = fi.readline()
            self.assertFalse(line)
            self.assertEqual(fi.lineno(), 1)
            self.assertEqual(fi.filelineno(), 0)
            self.assertEqual(fi.filename(), t4)
            fi.close()
        finally:
            remove_tempfiles(t1, t2, t3, t4)

    def test_files_that_dont_end_with_newline(self):
        t1 = t2 = None
        try:
            t1 = writeTmp(1, ["A\nB\nC"])
            t2 = writeTmp(2, ["D\nE\nF"])
            fi = FileInput(files=(t1, t2))
            lines = list(fi)
            self.assertEqual(lines, ["A\n", "B\n", "C", "D\n", "E\n", "F"])
            self.assertEqual(fi.filelineno(), 3)
            self.assertEqual(fi.lineno(), 6)
        finally:
            remove_tempfiles(t1, t2)

##     def test_unicode_filenames(self):
##         # XXX A unicode string is always returned by writeTmp.
##         #     So is this needed?
##         try:
##             t1 = writeTmp(1, ["A\nB"])
##             encoding = sys.getfilesystemencoding()
##             if encoding is None:
##                 encoding = 'ascii'
##             fi = FileInput(files=str(t1, encoding))
##             lines = list(fi)
##             self.assertEqual(lines, ["A\n", "B"])
##         finally:
##             remove_tempfiles(t1)

    def test_fileno(self):
        t1 = t2 = None
        try:
            t1 = writeTmp(1, ["A\nB"])
            t2 = writeTmp(2, ["C\nD"])
            fi = FileInput(files=(t1, t2))
            self.assertEqual(fi.fileno(), -1)
            line =next( fi)
            self.assertNotEqual(fi.fileno(), -1)
            fi.nextfile()
            self.assertEqual(fi.fileno(), -1)
            line = list(fi)
            self.assertEqual(fi.fileno(), -1)
        finally:
            remove_tempfiles(t1, t2)

    def test_opening_mode(self):
        try:
            # invalid mode, should raise ValueError
            fi = FileInput(mode="w")
            self.fail("FileInput should reject invalid mode argument")
        except ValueError:
            pass
        t1 = None
        try:
            # try opening in universal newline mode
            t1 = writeTmp(1, [b"A\nB\r\nC\rD"], mode="wb")
            fi = FileInput(files=t1, mode="U")
            lines = list(fi)
            self.assertEqual(lines, ["A\n", "B\n", "C\n", "D"])
        finally:
            remove_tempfiles(t1)

    def test_file_opening_hook(self):
        try:
            # cannot use openhook and inplace mode
            fi = FileInput(inplace=1, openhook=lambda f, m: None)
            self.fail("FileInput should raise if both inplace "
                             "and openhook arguments are given")
        except ValueError:
            pass
        try:
            fi = FileInput(openhook=1)
            self.fail("FileInput should check openhook for being callable")
        except ValueError:
            pass

        class CustomOpenHook:
            def __init__(self):
                self.invoked = False
            def __call__(self, *args):
                self.invoked = True
                return open(*args)

        t = writeTmp(1, ["\n"])
        self.addCleanup(remove_tempfiles, t)
        custom_open_hook = CustomOpenHook()
        with FileInput([t], openhook=custom_open_hook) as fi:
            fi.readline()
        self.assertTrue(custom_open_hook.invoked, "openhook not invoked")

    def test_context_manager(self):
        try:
            t1 = writeTmp(1, ["A\nB\nC"])
            t2 = writeTmp(2, ["D\nE\nF"])
            with FileInput(files=(t1, t2)) as fi:
                lines = list(fi)
            self.assertEqual(lines, ["A\n", "B\n", "C", "D\n", "E\n", "F"])
            self.assertEqual(fi.filelineno(), 3)
            self.assertEqual(fi.lineno(), 6)
            self.assertEqual(fi._files, ())
        finally:
            remove_tempfiles(t1, t2)

    def test_close_on_exception(self):
        try:
            t1 = writeTmp(1, [""])
            with FileInput(files=t1) as fi:
                raise IOError
        except IOError:
            self.assertEqual(fi._files, ())
        finally:
            remove_tempfiles(t1)

    def test_empty_files_list_specified_to_constructor(self):
        with FileInput(files=[]) as fi:
            self.assertEquals(fi._files, ('-',))

    def test__getitem__(self):
        """Tests invoking FileInput.__getitem__() with the current
           line number"""
        t = writeTmp(1, ["line1\n", "line2\n"])
        self.addCleanup(remove_tempfiles, t)
        with FileInput(files=[t]) as fi:
            retval1 = fi[0]
            self.assertEqual(retval1, "line1\n")
            retval2 = fi[1]
            self.assertEqual(retval2, "line2\n")

    def test__getitem__invalid_key(self):
        """Tests invoking FileInput.__getitem__() with an index unequal to
           the line number"""
        t = writeTmp(1, ["line1\n", "line2\n"])
        self.addCleanup(remove_tempfiles, t)
        with FileInput(files=[t]) as fi:
            with self.assertRaises(RuntimeError) as cm:
                fi[1]
        self.assertEquals(cm.exception.args, ("accessing lines out of order",))

    def test__getitem__eof(self):
        """Tests invoking FileInput.__getitem__() with the line number but at
           end-of-input"""
        t = writeTmp(1, [])
        self.addCleanup(remove_tempfiles, t)
        with FileInput(files=[t]) as fi:
            with self.assertRaises(IndexError) as cm:
                fi[0]
        self.assertEquals(cm.exception.args, ("end of input reached",))

    def test_nextfile_oserror_deleting_backup(self):
        """Tests invoking FileInput.nextfile() when the attempt to delete
           the backup file would raise OSError.  This error is expected to be
           silently ignored"""

        os_unlink_orig = os.unlink
        os_unlink_replacement = UnconditionallyRaise(OSError)
        try:
            t = writeTmp(1, ["\n"])
            self.addCleanup(remove_tempfiles, t)
            with FileInput(files=[t], inplace=True) as fi:
                next(fi) # make sure the file is opened
                os.unlink = os_unlink_replacement
                fi.nextfile()
        finally:
            os.unlink = os_unlink_orig

        # sanity check to make sure that our test scenario was actually hit
        self.assertTrue(os_unlink_replacement.invoked,
                        "os.unlink() was not invoked")

    def test_readline_os_fstat_raises_OSError(self):
        """Tests invoking FileInput.readline() when os.fstat() raises OSError.
           This exception should be silently discarded."""

        os_fstat_orig = os.fstat
        os_fstat_replacement = UnconditionallyRaise(OSError)
        try:
            t = writeTmp(1, ["\n"])
            self.addCleanup(remove_tempfiles, t)
            with FileInput(files=[t], inplace=True) as fi:
                os.fstat = os_fstat_replacement
                fi.readline()
        finally:
            os.fstat = os_fstat_orig

        # sanity check to make sure that our test scenario was actually hit
        self.assertTrue(os_fstat_replacement.invoked,
                        "os.fstat() was not invoked")

    @unittest.skipIf(not hasattr(os, "chmod"), "os.chmod does not exist")
    def test_readline_os_chmod_raises_OSError(self):
        """Tests invoking FileInput.readline() when os.chmod() raises OSError.
           This exception should be silently discarded."""

        os_chmod_orig = os.chmod
        os_chmod_replacement = UnconditionallyRaise(OSError)
        try:
            t = writeTmp(1, ["\n"])
            self.addCleanup(remove_tempfiles, t)
            with FileInput(files=[t], inplace=True) as fi:
                os.chmod = os_chmod_replacement
                fi.readline()
        finally:
            os.chmod = os_chmod_orig

        # sanity check to make sure that our test scenario was actually hit
        self.assertTrue(os_chmod_replacement.invoked,
                        "os.fstat() was not invoked")

    def test_fileno_when_ValueError_raised(self):
        class FilenoRaisesValueError(UnconditionallyRaise):
            def __init__(self):
                UnconditionallyRaise.__init__(self, ValueError)
            def fileno(self):
                self.__call__()

        unconditionally_raise_ValueError = FilenoRaisesValueError()
        t = writeTmp(1, ["\n"])
        self.addCleanup(remove_tempfiles, t)
        with FileInput(files=[t]) as fi:
            file_backup = fi._file
            try:
                fi._file = unconditionally_raise_ValueError
                result = fi.fileno()
            finally:
                fi._file = file_backup # make sure the file gets cleaned up

        # sanity check to make sure that our test scenario was actually hit
        self.assertTrue(unconditionally_raise_ValueError.invoked,
                        "_file.fileno() was not invoked")

        self.assertEqual(result, -1, "fileno() should return -1")

class MockFileInput:
    """A class that mocks out fileinput.FileInput for use during unit tests"""

    def __init__(self, files=None, inplace=False, backup="", bufsize=0,
                 mode="r", openhook=None):
        self.files = files
        self.inplace = inplace
        self.backup = backup
        self.bufsize = bufsize
        self.mode = mode
        self.openhook = openhook
        self._file = None
        self.invocation_counts = collections.defaultdict(lambda: 0)
        self.return_values = {}

    def close(self):
        self.invocation_counts["close"] += 1

    def nextfile(self):
        self.invocation_counts["nextfile"] += 1
        return self.return_values["nextfile"]

    def filename(self):
        self.invocation_counts["filename"] += 1
        return self.return_values["filename"]

    def lineno(self):
        self.invocation_counts["lineno"] += 1
        return self.return_values["lineno"]

    def filelineno(self):
        self.invocation_counts["filelineno"] += 1
        return self.return_values["filelineno"]

    def fileno(self):
        self.invocation_counts["fileno"] += 1
        return self.return_values["fileno"]

    def isfirstline(self):
        self.invocation_counts["isfirstline"] += 1
        return self.return_values["isfirstline"]

    def isstdin(self):
        self.invocation_counts["isstdin"] += 1
        return self.return_values["isstdin"]

class BaseFileInputGlobalMethodsTest(unittest.TestCase):
    """Base class for unit tests for the global function of
       the fileinput module."""

    def setUp(self):
        self._orig_state = fileinput._state
        self._orig_FileInput = fileinput.FileInput
        fileinput.FileInput = MockFileInput

    def tearDown(self):
        fileinput.FileInput = self._orig_FileInput
        fileinput._state = self._orig_state

    def assertExactlyOneInvocation(self, mock_file_input, method_name):
        # assert that the method with the given name was invoked once
        actual_count = mock_file_input.invocation_counts[method_name]
        self.assertEqual(actual_count, 1, method_name)
        # assert that no other unexpected methods were invoked
        actual_total_count = len(mock_file_input.invocation_counts)
        self.assertEqual(actual_total_count, 1)

class Test_fileinput_input(BaseFileInputGlobalMethodsTest):
    """Unit tests for fileinput.input()"""

    def test_state_is_not_None_and_state_file_is_not_None(self):
        """Tests invoking fileinput.input() when fileinput._state is not None
           and its _file attribute is also not None.  Expect RuntimeError to
           be raised with a meaningful error message and for fileinput._state
           to *not* be modified."""
        instance = MockFileInput()
        instance._file = object()
        fileinput._state = instance
        with self.assertRaises(RuntimeError) as cm:
            fileinput.input()
        self.assertEqual(("input() already active",), cm.exception.args)
        self.assertIs(instance, fileinput._state, "fileinput._state")

    def test_state_is_not_None_and_state_file_is_None(self):
        """Tests invoking fileinput.input() when fileinput._state is not None
           but its _file attribute *is* None.  Expect it to create and return
           a new fileinput.FileInput object with all method parameters passed
           explicitly to the __init__() method; also ensure that
           fileinput._state is set to the returned instance."""
        instance = MockFileInput()
        instance._file = None
        fileinput._state = instance
        self.do_test_call_input()

    def test_state_is_None(self):
        """Tests invoking fileinput.input() when fileinput._state is None
           Expect it to create and return a new fileinput.FileInput object
           with all method parameters passed explicitly to the __init__()
           method; also ensure that fileinput._state is set to the returned
           instance."""
        fileinput._state = None
        self.do_test_call_input()

    def do_test_call_input(self):
        """Tests that fileinput.input() creates a new fileinput.FileInput
           object, passing the given parameters unmodified to
           fileinput.FileInput.__init__().  Note that this test depends on the
           monkey patching of fileinput.FileInput done by setUp()."""
        files = object()
        inplace = object()
        backup = object()
        bufsize = object()
        mode = object()
        openhook = object()

        # call fileinput.input() with different values for each argument
        result = fileinput.input(files=files, inplace=inplace, backup=backup,
                                 bufsize=bufsize,
            mode=mode, openhook=openhook)

        # ensure fileinput._state was set to the returned object
        self.assertIs(result, fileinput._state, "fileinput._state")

        # ensure the parameters to fileinput.input() were passed directly
        # to FileInput.__init__()
        self.assertIs(files, result.files, "files")
        self.assertIs(inplace, result.inplace, "inplace")
        self.assertIs(backup, result.backup, "backup")
        self.assertIs(bufsize, result.bufsize, "bufsize")
        self.assertIs(mode, result.mode, "mode")
        self.assertIs(openhook, result.openhook, "openhook")

class Test_fileinput_close(BaseFileInputGlobalMethodsTest):
    """Unit tests for fileinput.close()"""

    def test_state_is_None(self):
        """Tests that fileinput.close() does nothing if fileinput._state
           is None"""
        fileinput._state = None
        fileinput.close()
        self.assertIsNone(fileinput._state)

    def test_state_is_not_None(self):
        """Tests that fileinput.close() invokes close() on fileinput._state
           and sets _state=None"""
        instance = MockFileInput()
        fileinput._state = instance
        fileinput.close()
        self.assertExactlyOneInvocation(instance, "close")
        self.assertIsNone(fileinput._state)

class Test_fileinput_nextfile(BaseFileInputGlobalMethodsTest):
    """Unit tests for fileinput.nextfile()"""

    def test_state_is_None(self):
        """Tests fileinput.nextfile() when fileinput._state is None.
           Ensure that it raises RuntimeError with a meaningful error message
           and does not modify fileinput._state"""
        fileinput._state = None
        with self.assertRaises(RuntimeError) as cm:
            fileinput.nextfile()
        self.assertEqual(("no active input()",), cm.exception.args)
        self.assertIsNone(fileinput._state)

    def test_state_is_not_None(self):
        """Tests fileinput.nextfile() when fileinput._state is not None.
           Ensure that it invokes fileinput._state.nextfile() exactly once,
           returns whatever it returns, and does not modify fileinput._state
           to point to a different object."""
        nextfile_retval = object()
        instance = MockFileInput()
        instance.return_values["nextfile"] = nextfile_retval
        fileinput._state = instance
        retval = fileinput.nextfile()
        self.assertExactlyOneInvocation(instance, "nextfile")
        self.assertIs(retval, nextfile_retval)
        self.assertIs(fileinput._state, instance)

class Test_fileinput_filename(BaseFileInputGlobalMethodsTest):
    """Unit tests for fileinput.filename()"""

    def test_state_is_None(self):
        """Tests fileinput.filename() when fileinput._state is None.
           Ensure that it raises RuntimeError with a meaningful error message
           and does not modify fileinput._state"""
        fileinput._state = None
        with self.assertRaises(RuntimeError) as cm:
            fileinput.filename()
        self.assertEqual(("no active input()",), cm.exception.args)
        self.assertIsNone(fileinput._state)

    def test_state_is_not_None(self):
        """Tests fileinput.filename() when fileinput._state is not None.
           Ensure that it invokes fileinput._state.filename() exactly once,
           returns whatever it returns, and does not modify fileinput._state
           to point to a different object."""
        filename_retval = object()
        instance = MockFileInput()
        instance.return_values["filename"] = filename_retval
        fileinput._state = instance
        retval = fileinput.filename()
        self.assertExactlyOneInvocation(instance, "filename")
        self.assertIs(retval, filename_retval)
        self.assertIs(fileinput._state, instance)

class Test_fileinput_lineno(BaseFileInputGlobalMethodsTest):
    """Unit tests for fileinput.lineno()"""

    def test_state_is_None(self):
        """Tests fileinput.lineno() when fileinput._state is None.
           Ensure that it raises RuntimeError with a meaningful error message
           and does not modify fileinput._state"""
        fileinput._state = None
        with self.assertRaises(RuntimeError) as cm:
            fileinput.lineno()
        self.assertEqual(("no active input()",), cm.exception.args)
        self.assertIsNone(fileinput._state)

    def test_state_is_not_None(self):
        """Tests fileinput.lineno() when fileinput._state is not None.
           Ensure that it invokes fileinput._state.lineno() exactly once,
           returns whatever it returns, and does not modify fileinput._state
           to point to a different object."""
        lineno_retval = object()
        instance = MockFileInput()
        instance.return_values["lineno"] = lineno_retval
        fileinput._state = instance
        retval = fileinput.lineno()
        self.assertExactlyOneInvocation(instance, "lineno")
        self.assertIs(retval, lineno_retval)
        self.assertIs(fileinput._state, instance)

class Test_fileinput_filelineno(BaseFileInputGlobalMethodsTest):
    """Unit tests for fileinput.filelineno()"""

    def test_state_is_None(self):
        """Tests fileinput.filelineno() when fileinput._state is None.
           Ensure that it raises RuntimeError with a meaningful error message
           and does not modify fileinput._state"""
        fileinput._state = None
        with self.assertRaises(RuntimeError) as cm:
            fileinput.filelineno()
        self.assertEqual(("no active input()",), cm.exception.args)
        self.assertIsNone(fileinput._state)

    def test_state_is_not_None(self):
        """Tests fileinput.filelineno() when fileinput._state is not None.
           Ensure that it invokes fileinput._state.filelineno() exactly once,
           returns whatever it returns, and does not modify fileinput._state
           to point to a different object."""
        filelineno_retval = object()
        instance = MockFileInput()
        instance.return_values["filelineno"] = filelineno_retval
        fileinput._state = instance
        retval = fileinput.filelineno()
        self.assertExactlyOneInvocation(instance, "filelineno")
        self.assertIs(retval, filelineno_retval)
        self.assertIs(fileinput._state, instance)

class Test_fileinput_fileno(BaseFileInputGlobalMethodsTest):
    """Unit tests for fileinput.fileno()"""

    def test_state_is_None(self):
        """Tests fileinput.fileno() when fileinput._state is None.
           Ensure that it raises RuntimeError with a meaningful error message
           and does not modify fileinput._state"""
        fileinput._state = None
        with self.assertRaises(RuntimeError) as cm:
            fileinput.fileno()
        self.assertEqual(("no active input()",), cm.exception.args)
        self.assertIsNone(fileinput._state)

    def test_state_is_not_None(self):
        """Tests fileinput.fileno() when fileinput._state is not None.
           Ensure that it invokes fileinput._state.fileno() exactly once,
           returns whatever it returns, and does not modify fileinput._state
           to point to a different object."""
        fileno_retval = object()
        instance = MockFileInput()
        instance.return_values["fileno"] = fileno_retval
        instance.fileno_retval = fileno_retval
        fileinput._state = instance
        retval = fileinput.fileno()
        self.assertExactlyOneInvocation(instance, "fileno")
        self.assertIs(retval, fileno_retval)
        self.assertIs(fileinput._state, instance)

class Test_fileinput_isfirstline(BaseFileInputGlobalMethodsTest):
    """Unit tests for fileinput.isfirstline()"""

    def test_state_is_None(self):
        """Tests fileinput.isfirstline() when fileinput._state is None.
           Ensure that it raises RuntimeError with a meaningful error message
           and does not modify fileinput._state"""
        fileinput._state = None
        with self.assertRaises(RuntimeError) as cm:
            fileinput.isfirstline()
        self.assertEqual(("no active input()",), cm.exception.args)
        self.assertIsNone(fileinput._state)

    def test_state_is_not_None(self):
        """Tests fileinput.isfirstline() when fileinput._state is not None.
           Ensure that it invokes fileinput._state.isfirstline() exactly once,
           returns whatever it returns, and does not modify fileinput._state
           to point to a different object."""
        isfirstline_retval = object()
        instance = MockFileInput()
        instance.return_values["isfirstline"] = isfirstline_retval
        fileinput._state = instance
        retval = fileinput.isfirstline()
        self.assertExactlyOneInvocation(instance, "isfirstline")
        self.assertIs(retval, isfirstline_retval)
        self.assertIs(fileinput._state, instance)

class Test_fileinput_isstdin(BaseFileInputGlobalMethodsTest):
    """Unit tests for fileinput.isstdin()"""

    def test_state_is_None(self):
        """Tests fileinput.isstdin() when fileinput._state is None.
           Ensure that it raises RuntimeError with a meaningful error message
           and does not modify fileinput._state"""
        fileinput._state = None
        with self.assertRaises(RuntimeError) as cm:
            fileinput.isstdin()
        self.assertEqual(("no active input()",), cm.exception.args)
        self.assertIsNone(fileinput._state)

    def test_state_is_not_None(self):
        """Tests fileinput.isstdin() when fileinput._state is not None.
           Ensure that it invokes fileinput._state.isstdin() exactly once,
           returns whatever it returns, and does not modify fileinput._state
           to point to a different object."""
        isstdin_retval = object()
        instance = MockFileInput()
        instance.return_values["isstdin"] = isstdin_retval
        fileinput._state = instance
        retval = fileinput.isstdin()
        self.assertExactlyOneInvocation(instance, "isstdin")
        self.assertIs(retval, isstdin_retval)
        self.assertIs(fileinput._state, instance)

class InvocationRecorder:
    def __init__(self):
        self.invocation_count = 0
    def __call__(self, *args, **kwargs):
        self.invocation_count += 1
        self.last_invocation = (args, kwargs)

class Test_hook_compressed(unittest.TestCase):
    """Unit tests for fileinput.hook_compressed()"""

    def setUp(self):
        self.fake_open = InvocationRecorder()

    def test_empty_string(self):
        self.do_test_use_builtin_open("", 1)

    def test_no_ext(self):
        self.do_test_use_builtin_open("abcd", 2)

    def test_gz_ext(self):
        original_open = gzip.open
        gzip.open = self.fake_open
        try:
            result = fileinput.hook_compressed("test.gz", 3)
        finally:
            gzip.open = original_open

        self.assertEqual(self.fake_open.invocation_count, 1)
        self.assertEqual(self.fake_open.last_invocation, (("test.gz", 3), {}))

    def test_bz2_ext(self):
        original_open = bz2.BZ2File
        bz2.BZ2File = self.fake_open
        try:
            result = fileinput.hook_compressed("test.bz2", 4)
        finally:
            bz2.BZ2File = original_open

        self.assertEqual(self.fake_open.invocation_count, 1)
        self.assertEqual(self.fake_open.last_invocation, (("test.bz2", 4), {}))

    def test_blah_ext(self):
        self.do_test_use_builtin_open("abcd.blah", 5)

    def test_Gz_ext(self):
        self.do_test_use_builtin_open("abcd.Gz", 6)

    def test_Bz2_ext(self):
        self.do_test_use_builtin_open("abcd.Bz2", 7)

    def do_test_use_builtin_open(self, filename, mode):
        original_open = self.replace_builtin_open(self.fake_open)
        try:
            result = fileinput.hook_compressed(filename, mode)
        finally:
            self.replace_builtin_open(original_open)

        self.assertEqual(self.fake_open.invocation_count, 1)
        self.assertEqual(self.fake_open.last_invocation,
                         ((filename, mode), {}))

    @staticmethod
    def replace_builtin_open(new_open_func):
        builtins_type = type(__builtins__)
        if builtins_type is dict:
            original_open = __builtins__["open"]
            __builtins__["open"] = new_open_func
        elif builtins_type is types.ModuleType:
            original_open = __builtins__.open
            __builtins__.open = new_open_func
        else:
            raise RuntimeError(
                "unknown __builtins__ type: %r (unable to replace open)" %
                builtins_type)

        return original_open

class Test_hook_encoded(unittest.TestCase):
    """Unit tests for fileinput.hook_encoded()"""

    def test(self):
        encoding = object()
        result = fileinput.hook_encoded(encoding)

        fake_open = InvocationRecorder()
        original_open = codecs.open
        codecs.open = fake_open
        try:
            filename = object()
            mode = object()
            open_result = result(filename, mode)
        finally:
            codecs.open = original_open

        self.assertEqual(fake_open.invocation_count, 1)

        args = fake_open.last_invocation[0]
        self.assertIs(args[0], filename)
        self.assertIs(args[1], mode)
        self.assertIs(args[2], encoding)

def test_main():
    run_unittest(
        BufferSizesTests,
        FileInputTests,
        Test_fileinput_input,
        Test_fileinput_close,
        Test_fileinput_nextfile,
        Test_fileinput_filename,
        Test_fileinput_lineno,
        Test_fileinput_filelineno,
        Test_fileinput_fileno,
        Test_fileinput_isfirstline,
        Test_fileinput_isstdin,
        Test_hook_compressed,
        Test_hook_encoded,
    )

if __name__ == "__main__":
    test_main()