/lib-python/2.7/test/test_doctest.py

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# -*- coding: utf-8 -*-
"""
Test script for doctest.
"""

import sys
from test import test_support
import doctest

# NOTE: There are some additional tests relating to interaction with
#       zipimport in the test_zipimport_support test module.

######################################################################
## Sample Objects (used by test cases)
######################################################################

def sample_func(v):
    """
    Blah blah

    >>> print sample_func(22)
    44

    Yee ha!
    """
    return v+v

class SampleClass:
    """
    >>> print 1
    1

    >>> # comments get ignored.  so are empty PS1 and PS2 prompts:
    >>>
    ...

    Multiline example:
    >>> sc = SampleClass(3)
    >>> for i in range(10):
    ...     sc = sc.double()
    ...     print sc.get(),
    6 12 24 48 96 192 384 768 1536 3072
    """
    def __init__(self, val):
        """
        >>> print SampleClass(12).get()
        12
        """
        self.val = val

    def double(self):
        """
        >>> print SampleClass(12).double().get()
        24
        """
        return SampleClass(self.val + self.val)

    def get(self):
        """
        >>> print SampleClass(-5).get()
        -5
        """
        return self.val

    def a_staticmethod(v):
        """
        >>> print SampleClass.a_staticmethod(10)
        11
        """
        return v+1
    a_staticmethod = staticmethod(a_staticmethod)

    def a_classmethod(cls, v):
        """
        >>> print SampleClass.a_classmethod(10)
        12
        >>> print SampleClass(0).a_classmethod(10)
        12
        """
        return v+2
    a_classmethod = classmethod(a_classmethod)

    a_property = property(get, doc="""
        >>> print SampleClass(22).a_property
        22
        """)

    class NestedClass:
        """
        >>> x = SampleClass.NestedClass(5)
        >>> y = x.square()
        >>> print y.get()
        25
        """
        def __init__(self, val=0):
            """
            >>> print SampleClass.NestedClass().get()
            0
            """
            self.val = val
        def square(self):
            return SampleClass.NestedClass(self.val*self.val)
        def get(self):
            return self.val

class SampleNewStyleClass(object):
    r"""
    >>> print '1\n2\n3'
    1
    2
    3
    """
    def __init__(self, val):
        """
        >>> print SampleNewStyleClass(12).get()
        12
        """
        self.val = val

    def double(self):
        """
        >>> print SampleNewStyleClass(12).double().get()
        24
        """
        return SampleNewStyleClass(self.val + self.val)

    def get(self):
        """
        >>> print SampleNewStyleClass(-5).get()
        -5
        """
        return self.val

######################################################################
## Fake stdin (for testing interactive debugging)
######################################################################

class _FakeInput:
    """
    A fake input stream for pdb's interactive debugger.  Whenever a
    line is read, print it (to simulate the user typing it), and then
    return it.  The set of lines to return is specified in the
    constructor; they should not have trailing newlines.
    """
    def __init__(self, lines):
        self.lines = lines

    def readline(self):
        line = self.lines.pop(0)
        print line
        return line+'\n'

######################################################################
## Test Cases
######################################################################

def test_Example(): r"""
Unit tests for the `Example` class.

Example is a simple container class that holds:
  - `source`: A source string.
  - `want`: An expected output string.
  - `exc_msg`: An expected exception message string (or None if no
    exception is expected).
  - `lineno`: A line number (within the docstring).
  - `indent`: The example's indentation in the input string.
  - `options`: An option dictionary, mapping option flags to True or
    False.

These attributes are set by the constructor.  `source` and `want` are
required; the other attributes all have default values:

    >>> example = doctest.Example('print 1', '1\n')
    >>> (example.source, example.want, example.exc_msg,
    ...  example.lineno, example.indent, example.options)
    ('print 1\n', '1\n', None, 0, 0, {})

The first three attributes (`source`, `want`, and `exc_msg`) may be
specified positionally; the remaining arguments should be specified as
keyword arguments:

    >>> exc_msg = 'IndexError: pop from an empty list'
    >>> example = doctest.Example('[].pop()', '', exc_msg,
    ...                           lineno=5, indent=4,
    ...                           options={doctest.ELLIPSIS: True})
    >>> (example.source, example.want, example.exc_msg,
    ...  example.lineno, example.indent, example.options)
    ('[].pop()\n', '', 'IndexError: pop from an empty list\n', 5, 4, {8: True})

The constructor normalizes the `source` string to end in a newline:

    Source spans a single line: no terminating newline.
    >>> e = doctest.Example('print 1', '1\n')
    >>> e.source, e.want
    ('print 1\n', '1\n')

    >>> e = doctest.Example('print 1\n', '1\n')
    >>> e.source, e.want
    ('print 1\n', '1\n')

    Source spans multiple lines: require terminating newline.
    >>> e = doctest.Example('print 1;\nprint 2\n', '1\n2\n')
    >>> e.source, e.want
    ('print 1;\nprint 2\n', '1\n2\n')

    >>> e = doctest.Example('print 1;\nprint 2', '1\n2\n')
    >>> e.source, e.want
    ('print 1;\nprint 2\n', '1\n2\n')

    Empty source string (which should never appear in real examples)
    >>> e = doctest.Example('', '')
    >>> e.source, e.want
    ('\n', '')

The constructor normalizes the `want` string to end in a newline,
unless it's the empty string:

    >>> e = doctest.Example('print 1', '1\n')
    >>> e.source, e.want
    ('print 1\n', '1\n')

    >>> e = doctest.Example('print 1', '1')
    >>> e.source, e.want
    ('print 1\n', '1\n')

    >>> e = doctest.Example('print', '')
    >>> e.source, e.want
    ('print\n', '')

The constructor normalizes the `exc_msg` string to end in a newline,
unless it's `None`:

    Message spans one line
    >>> exc_msg = 'IndexError: pop from an empty list'
    >>> e = doctest.Example('[].pop()', '', exc_msg)
    >>> e.exc_msg
    'IndexError: pop from an empty list\n'

    >>> exc_msg = 'IndexError: pop from an empty list\n'
    >>> e = doctest.Example('[].pop()', '', exc_msg)
    >>> e.exc_msg
    'IndexError: pop from an empty list\n'

    Message spans multiple lines
    >>> exc_msg = 'ValueError: 1\n  2'
    >>> e = doctest.Example('raise ValueError("1\n  2")', '', exc_msg)
    >>> e.exc_msg
    'ValueError: 1\n  2\n'

    >>> exc_msg = 'ValueError: 1\n  2\n'
    >>> e = doctest.Example('raise ValueError("1\n  2")', '', exc_msg)
    >>> e.exc_msg
    'ValueError: 1\n  2\n'

    Empty (but non-None) exception message (which should never appear
    in real examples)
    >>> exc_msg = ''
    >>> e = doctest.Example('raise X()', '', exc_msg)
    >>> e.exc_msg
    '\n'
"""

def test_DocTest(): r"""
Unit tests for the `DocTest` class.

DocTest is a collection of examples, extracted from a docstring, along
with information about where the docstring comes from (a name,
filename, and line number).  The docstring is parsed by the `DocTest`
constructor:

    >>> docstring = '''
    ...     >>> print 12
    ...     12
    ...
    ... Non-example text.
    ...
    ...     >>> print 'another\example'
    ...     another
    ...     example
    ... '''
    >>> globs = {} # globals to run the test in.
    >>> parser = doctest.DocTestParser()
    >>> test = parser.get_doctest(docstring, globs, 'some_test',
    ...                           'some_file', 20)
    >>> print test
    <DocTest some_test from some_file:20 (2 examples)>
    >>> len(test.examples)
    2
    >>> e1, e2 = test.examples
    >>> (e1.source, e1.want, e1.lineno)
    ('print 12\n', '12\n', 1)
    >>> (e2.source, e2.want, e2.lineno)
    ("print 'another\\example'\n", 'another\nexample\n', 6)

Source information (name, filename, and line number) is available as
attributes on the doctest object:

    >>> (test.name, test.filename, test.lineno)
    ('some_test', 'some_file', 20)

The line number of an example within its containing file is found by
adding the line number of the example and the line number of its
containing test:

    >>> test.lineno + e1.lineno
    21
    >>> test.lineno + e2.lineno
    26

If the docstring contains inconsistant leading whitespace in the
expected output of an example, then `DocTest` will raise a ValueError:

    >>> docstring = r'''
    ...       >>> print 'bad\nindentation'
    ...       bad
    ...     indentation
    ...     '''
    >>> parser.get_doctest(docstring, globs, 'some_test', 'filename', 0)
    Traceback (most recent call last):
    ValueError: line 4 of the docstring for some_test has inconsistent leading whitespace: 'indentation'

If the docstring contains inconsistent leading whitespace on
continuation lines, then `DocTest` will raise a ValueError:

    >>> docstring = r'''
    ...       >>> print ('bad indentation',
    ...     ...          2)
    ...       ('bad', 'indentation')
    ...     '''
    >>> parser.get_doctest(docstring, globs, 'some_test', 'filename', 0)
    Traceback (most recent call last):
    ValueError: line 2 of the docstring for some_test has inconsistent leading whitespace: '...          2)'

If there's no blank space after a PS1 prompt ('>>>'), then `DocTest`
will raise a ValueError:

    >>> docstring = '>>>print 1\n1'
    >>> parser.get_doctest(docstring, globs, 'some_test', 'filename', 0)
    Traceback (most recent call last):
    ValueError: line 1 of the docstring for some_test lacks blank after >>>: '>>>print 1'

If there's no blank space after a PS2 prompt ('...'), then `DocTest`
will raise a ValueError:

    >>> docstring = '>>> if 1:\n...print 1\n1'
    >>> parser.get_doctest(docstring, globs, 'some_test', 'filename', 0)
    Traceback (most recent call last):
    ValueError: line 2 of the docstring for some_test lacks blank after ...: '...print 1'

"""

def test_DocTestFinder(): r"""
Unit tests for the `DocTestFinder` class.

DocTestFinder is used to extract DocTests from an object's docstring
and the docstrings of its contained objects.  It can be used with
modules, functions, classes, methods, staticmethods, classmethods, and
properties.

Finding Tests in Functions
~~~~~~~~~~~~~~~~~~~~~~~~~~
For a function whose docstring contains examples, DocTestFinder.find()
will return a single test (for that function's docstring):

    >>> finder = doctest.DocTestFinder()

We'll simulate a __file__ attr that ends in pyc:

    >>> import test.test_doctest
    >>> old = test.test_doctest.__file__
    >>> test.test_doctest.__file__ = 'test_doctest.pyc'

    >>> tests = finder.find(sample_func)

    >>> print tests  # doctest: +ELLIPSIS
    [<DocTest sample_func from ...:17 (1 example)>]

The exact name depends on how test_doctest was invoked, so allow for
leading path components.

    >>> tests[0].filename # doctest: +ELLIPSIS
    '...test_doctest.py'

    >>> test.test_doctest.__file__ = old


    >>> e = tests[0].examples[0]
    >>> (e.source, e.want, e.lineno)
    ('print sample_func(22)\n', '44\n', 3)

By default, tests are created for objects with no docstring:

    >>> def no_docstring(v):
    ...     pass
    >>> finder.find(no_docstring)
    []

However, the optional argument `exclude_empty` to the DocTestFinder
constructor can be used to exclude tests for objects with empty
docstrings:

    >>> def no_docstring(v):
    ...     pass
    >>> excl_empty_finder = doctest.DocTestFinder(exclude_empty=True)
    >>> excl_empty_finder.find(no_docstring)
    []

If the function has a docstring with no examples, then a test with no
examples is returned.  (This lets `DocTestRunner` collect statistics
about which functions have no tests -- but is that useful?  And should
an empty test also be created when there's no docstring?)

    >>> def no_examples(v):
    ...     ''' no doctest examples '''
    >>> finder.find(no_examples) # doctest: +ELLIPSIS
    [<DocTest no_examples from ...:1 (no examples)>]

Finding Tests in Classes
~~~~~~~~~~~~~~~~~~~~~~~~
For a class, DocTestFinder will create a test for the class's
docstring, and will recursively explore its contents, including
methods, classmethods, staticmethods, properties, and nested classes.

    >>> finder = doctest.DocTestFinder()
    >>> tests = finder.find(SampleClass)
    >>> for t in tests:
    ...     print '%2s  %s' % (len(t.examples), t.name)
     3  SampleClass
     3  SampleClass.NestedClass
     1  SampleClass.NestedClass.__init__
     1  SampleClass.__init__
     2  SampleClass.a_classmethod
     1  SampleClass.a_property
     1  SampleClass.a_staticmethod
     1  SampleClass.double
     1  SampleClass.get

New-style classes are also supported:

    >>> tests = finder.find(SampleNewStyleClass)
    >>> for t in tests:
    ...     print '%2s  %s' % (len(t.examples), t.name)
     1  SampleNewStyleClass
     1  SampleNewStyleClass.__init__
     1  SampleNewStyleClass.double
     1  SampleNewStyleClass.get

Finding Tests in Modules
~~~~~~~~~~~~~~~~~~~~~~~~
For a module, DocTestFinder will create a test for the class's
docstring, and will recursively explore its contents, including
functions, classes, and the `__test__` dictionary, if it exists:

    >>> # A module
    >>> import types
    >>> m = types.ModuleType('some_module')
    >>> def triple(val):
    ...     '''
    ...     >>> print triple(11)
    ...     33
    ...     '''
    ...     return val*3
    >>> m.__dict__.update({
    ...     'sample_func': sample_func,
    ...     'SampleClass': SampleClass,
    ...     '__doc__': '''
    ...         Module docstring.
    ...             >>> print 'module'
    ...             module
    ...         ''',
    ...     '__test__': {
    ...         'd': '>>> print 6\n6\n>>> print 7\n7\n',
    ...         'c': triple}})

    >>> finder = doctest.DocTestFinder()
    >>> # Use module=test.test_doctest, to prevent doctest from
    >>> # ignoring the objects since they weren't defined in m.
    >>> import test.test_doctest
    >>> tests = finder.find(m, module=test.test_doctest)
    >>> for t in tests:
    ...     print '%2s  %s' % (len(t.examples), t.name)
     1  some_module
     3  some_module.SampleClass
     3  some_module.SampleClass.NestedClass
     1  some_module.SampleClass.NestedClass.__init__
     1  some_module.SampleClass.__init__
     2  some_module.SampleClass.a_classmethod
     1  some_module.SampleClass.a_property
     1  some_module.SampleClass.a_staticmethod
     1  some_module.SampleClass.double
     1  some_module.SampleClass.get
     1  some_module.__test__.c
     2  some_module.__test__.d
     1  some_module.sample_func

Duplicate Removal
~~~~~~~~~~~~~~~~~
If a single object is listed twice (under different names), then tests
will only be generated for it once:

    >>> from test import doctest_aliases
    >>> assert doctest_aliases.TwoNames.f
    >>> assert doctest_aliases.TwoNames.g
    >>> tests = excl_empty_finder.find(doctest_aliases)
    >>> print len(tests)
    2
    >>> print tests[0].name
    test.doctest_aliases.TwoNames

    TwoNames.f and TwoNames.g are bound to the same object.
    We can't guess which will be found in doctest's traversal of
    TwoNames.__dict__ first, so we have to allow for either.

    >>> tests[1].name.split('.')[-1] in ['f', 'g']
    True

Empty Tests
~~~~~~~~~~~
By default, an object with no doctests doesn't create any tests:

    >>> tests = doctest.DocTestFinder().find(SampleClass)
    >>> for t in tests:
    ...     print '%2s  %s' % (len(t.examples), t.name)
     3  SampleClass
     3  SampleClass.NestedClass
     1  SampleClass.NestedClass.__init__
     1  SampleClass.__init__
     2  SampleClass.a_classmethod
     1  SampleClass.a_property
     1  SampleClass.a_staticmethod
     1  SampleClass.double
     1  SampleClass.get

By default, that excluded objects with no doctests.  exclude_empty=False
tells it to include (empty) tests for objects with no doctests.  This feature
is really to support backward compatibility in what doctest.master.summarize()
displays.

    >>> tests = doctest.DocTestFinder(exclude_empty=False).find(SampleClass)
    >>> for t in tests:
    ...     print '%2s  %s' % (len(t.examples), t.name)
     3  SampleClass
     3  SampleClass.NestedClass
     1  SampleClass.NestedClass.__init__
     0  SampleClass.NestedClass.get
     0  SampleClass.NestedClass.square
     1  SampleClass.__init__
     2  SampleClass.a_classmethod
     1  SampleClass.a_property
     1  SampleClass.a_staticmethod
     1  SampleClass.double
     1  SampleClass.get

Turning off Recursion
~~~~~~~~~~~~~~~~~~~~~
DocTestFinder can be told not to look for tests in contained objects
using the `recurse` flag:

    >>> tests = doctest.DocTestFinder(recurse=False).find(SampleClass)
    >>> for t in tests:
    ...     print '%2s  %s' % (len(t.examples), t.name)
     3  SampleClass

Line numbers
~~~~~~~~~~~~
DocTestFinder finds the line number of each example:

    >>> def f(x):
    ...     '''
    ...     >>> x = 12
    ...
    ...     some text
    ...
    ...     >>> # examples are not created for comments & bare prompts.
    ...     >>>
    ...     ...
    ...
    ...     >>> for x in range(10):
    ...     ...     print x,
    ...     0 1 2 3 4 5 6 7 8 9
    ...     >>> x//2
    ...     6
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> [e.lineno for e in test.examples]
    [1, 9, 12]
"""

def test_DocTestParser(): r"""
Unit tests for the `DocTestParser` class.

DocTestParser is used to parse docstrings containing doctest examples.

The `parse` method divides a docstring into examples and intervening
text:

    >>> s = '''
    ...     >>> x, y = 2, 3  # no output expected
    ...     >>> if 1:
    ...     ...     print x
    ...     ...     print y
    ...     2
    ...     3
    ...
    ...     Some text.
    ...     >>> x+y
    ...     5
    ...     '''
    >>> parser = doctest.DocTestParser()
    >>> for piece in parser.parse(s):
    ...     if isinstance(piece, doctest.Example):
    ...         print 'Example:', (piece.source, piece.want, piece.lineno)
    ...     else:
    ...         print '   Text:', `piece`
       Text: '\n'
    Example: ('x, y = 2, 3  # no output expected\n', '', 1)
       Text: ''
    Example: ('if 1:\n    print x\n    print y\n', '2\n3\n', 2)
       Text: '\nSome text.\n'
    Example: ('x+y\n', '5\n', 9)
       Text: ''

The `get_examples` method returns just the examples:

    >>> for piece in parser.get_examples(s):
    ...     print (piece.source, piece.want, piece.lineno)
    ('x, y = 2, 3  # no output expected\n', '', 1)
    ('if 1:\n    print x\n    print y\n', '2\n3\n', 2)
    ('x+y\n', '5\n', 9)

The `get_doctest` method creates a Test from the examples, along with the
given arguments:

    >>> test = parser.get_doctest(s, {}, 'name', 'filename', lineno=5)
    >>> (test.name, test.filename, test.lineno)
    ('name', 'filename', 5)
    >>> for piece in test.examples:
    ...     print (piece.source, piece.want, piece.lineno)
    ('x, y = 2, 3  # no output expected\n', '', 1)
    ('if 1:\n    print x\n    print y\n', '2\n3\n', 2)
    ('x+y\n', '5\n', 9)
"""

class test_DocTestRunner:
    def basics(): r"""
Unit tests for the `DocTestRunner` class.

DocTestRunner is used to run DocTest test cases, and to accumulate
statistics.  Here's a simple DocTest case we can use:

    >>> def f(x):
    ...     '''
    ...     >>> x = 12
    ...     >>> print x
    ...     12
    ...     >>> x//2
    ...     6
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]

The main DocTestRunner interface is the `run` method, which runs a
given DocTest case in a given namespace (globs).  It returns a tuple
`(f,t)`, where `f` is the number of failed tests and `t` is the number
of tried tests.

    >>> doctest.DocTestRunner(verbose=False).run(test)
    TestResults(failed=0, attempted=3)

If any example produces incorrect output, then the test runner reports
the failure and proceeds to the next example:

    >>> def f(x):
    ...     '''
    ...     >>> x = 12
    ...     >>> print x
    ...     14
    ...     >>> x//2
    ...     6
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=True).run(test)
    ... # doctest: +ELLIPSIS
    Trying:
        x = 12
    Expecting nothing
    ok
    Trying:
        print x
    Expecting:
        14
    **********************************************************************
    File ..., line 4, in f
    Failed example:
        print x
    Expected:
        14
    Got:
        12
    Trying:
        x//2
    Expecting:
        6
    ok
    TestResults(failed=1, attempted=3)
"""
    def verbose_flag(): r"""
The `verbose` flag makes the test runner generate more detailed
output:

    >>> def f(x):
    ...     '''
    ...     >>> x = 12
    ...     >>> print x
    ...     12
    ...     >>> x//2
    ...     6
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]

    >>> doctest.DocTestRunner(verbose=True).run(test)
    Trying:
        x = 12
    Expecting nothing
    ok
    Trying:
        print x
    Expecting:
        12
    ok
    Trying:
        x//2
    Expecting:
        6
    ok
    TestResults(failed=0, attempted=3)

If the `verbose` flag is unspecified, then the output will be verbose
iff `-v` appears in sys.argv:

    >>> # Save the real sys.argv list.
    >>> old_argv = sys.argv

    >>> # If -v does not appear in sys.argv, then output isn't verbose.
    >>> sys.argv = ['test']
    >>> doctest.DocTestRunner().run(test)
    TestResults(failed=0, attempted=3)

    >>> # If -v does appear in sys.argv, then output is verbose.
    >>> sys.argv = ['test', '-v']
    >>> doctest.DocTestRunner().run(test)
    Trying:
        x = 12
    Expecting nothing
    ok
    Trying:
        print x
    Expecting:
        12
    ok
    Trying:
        x//2
    Expecting:
        6
    ok
    TestResults(failed=0, attempted=3)

    >>> # Restore sys.argv
    >>> sys.argv = old_argv

In the remaining examples, the test runner's verbosity will be
explicitly set, to ensure that the test behavior is consistent.
    """
    def exceptions(): r"""
Tests of `DocTestRunner`'s exception handling.

An expected exception is specified with a traceback message.  The
lines between the first line and the type/value may be omitted or
replaced with any other string:

    >>> def f(x):
    ...     '''
    ...     >>> x = 12
    ...     >>> print x//0
    ...     Traceback (most recent call last):
    ...     ZeroDivisionError: integer division or modulo by zero
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    TestResults(failed=0, attempted=2)

An example may not generate output before it raises an exception; if
it does, then the traceback message will not be recognized as
signaling an expected exception, so the example will be reported as an
unexpected exception:

    >>> def f(x):
    ...     '''
    ...     >>> x = 12
    ...     >>> print 'pre-exception output', x//0
    ...     pre-exception output
    ...     Traceback (most recent call last):
    ...     ZeroDivisionError: integer division or modulo by zero
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 4, in f
    Failed example:
        print 'pre-exception output', x//0
    Exception raised:
        ...
        ZeroDivisionError: integer division or modulo by zero
    TestResults(failed=1, attempted=2)

Exception messages may contain newlines:

    >>> def f(x):
    ...     r'''
    ...     >>> raise ValueError, 'multi\nline\nmessage'
    ...     Traceback (most recent call last):
    ...     ValueError: multi
    ...     line
    ...     message
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    TestResults(failed=0, attempted=1)

If an exception is expected, but an exception with the wrong type or
message is raised, then it is reported as a failure:

    >>> def f(x):
    ...     r'''
    ...     >>> raise ValueError, 'message'
    ...     Traceback (most recent call last):
    ...     ValueError: wrong message
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 3, in f
    Failed example:
        raise ValueError, 'message'
    Expected:
        Traceback (most recent call last):
        ValueError: wrong message
    Got:
        Traceback (most recent call last):
        ...
        ValueError: message
    TestResults(failed=1, attempted=1)

However, IGNORE_EXCEPTION_DETAIL can be used to allow a mismatch in the
detail:

    >>> def f(x):
    ...     r'''
    ...     >>> raise ValueError, 'message' #doctest: +IGNORE_EXCEPTION_DETAIL
    ...     Traceback (most recent call last):
    ...     ValueError: wrong message
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    TestResults(failed=0, attempted=1)

IGNORE_EXCEPTION_DETAIL also ignores difference in exception formatting
between Python versions. For example, in Python 3.x, the module path of
the exception is in the output, but this will fail under Python 2:

    >>> def f(x):
    ...     r'''
    ...     >>> from httplib import HTTPException
    ...     >>> raise HTTPException('message')
    ...     Traceback (most recent call last):
    ...     httplib.HTTPException: message
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 4, in f
    Failed example:
        raise HTTPException('message')
    Expected:
        Traceback (most recent call last):
        httplib.HTTPException: message
    Got:
        Traceback (most recent call last):
        ...
        HTTPException: message
    TestResults(failed=1, attempted=2)

But in Python 2 the module path is not included, an therefore a test must look
like the following test to succeed in Python 2. But that test will fail under
Python 3.

    >>> def f(x):
    ...     r'''
    ...     >>> from httplib import HTTPException
    ...     >>> raise HTTPException('message')
    ...     Traceback (most recent call last):
    ...     HTTPException: message
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    TestResults(failed=0, attempted=2)

However, with IGNORE_EXCEPTION_DETAIL, the module name of the exception
(if any) will be ignored:

    >>> def f(x):
    ...     r'''
    ...     >>> from httplib import HTTPException
    ...     >>> raise HTTPException('message') #doctest: +IGNORE_EXCEPTION_DETAIL
    ...     Traceback (most recent call last):
    ...     HTTPException: message
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    TestResults(failed=0, attempted=2)

The module path will be completely ignored, so two different module paths will
still pass if IGNORE_EXCEPTION_DETAIL is given. This is intentional, so it can
be used when exceptions have changed module.

    >>> def f(x):
    ...     r'''
    ...     >>> from httplib import HTTPException
    ...     >>> raise HTTPException('message') #doctest: +IGNORE_EXCEPTION_DETAIL
    ...     Traceback (most recent call last):
    ...     foo.bar.HTTPException: message
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    TestResults(failed=0, attempted=2)

But IGNORE_EXCEPTION_DETAIL does not allow a mismatch in the exception type:

    >>> def f(x):
    ...     r'''
    ...     >>> raise ValueError, 'message' #doctest: +IGNORE_EXCEPTION_DETAIL
    ...     Traceback (most recent call last):
    ...     TypeError: wrong type
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 3, in f
    Failed example:
        raise ValueError, 'message' #doctest: +IGNORE_EXCEPTION_DETAIL
    Expected:
        Traceback (most recent call last):
        TypeError: wrong type
    Got:
        Traceback (most recent call last):
        ...
        ValueError: message
    TestResults(failed=1, attempted=1)

If an exception is raised but not expected, then it is reported as an
unexpected exception:

    >>> def f(x):
    ...     r'''
    ...     >>> 1//0
    ...     0
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 3, in f
    Failed example:
        1//0
    Exception raised:
        Traceback (most recent call last):
        ...
        ZeroDivisionError: integer division or modulo by zero
    TestResults(failed=1, attempted=1)
"""
    def displayhook(): r"""
Test that changing sys.displayhook doesn't matter for doctest.

    >>> import sys
    >>> orig_displayhook = sys.displayhook
    >>> def my_displayhook(x):
    ...     print('hi!')
    >>> sys.displayhook = my_displayhook
    >>> def f():
    ...     '''
    ...     >>> 3
    ...     3
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> r = doctest.DocTestRunner(verbose=False).run(test)
    >>> post_displayhook = sys.displayhook

    We need to restore sys.displayhook now, so that we'll be able to test
    results.

    >>> sys.displayhook = orig_displayhook

    Ok, now we can check that everything is ok.

    >>> r
    TestResults(failed=0, attempted=1)
    >>> post_displayhook is my_displayhook
    True
"""
    def optionflags(): r"""
Tests of `DocTestRunner`'s option flag handling.

Several option flags can be used to customize the behavior of the test
runner.  These are defined as module constants in doctest, and passed
to the DocTestRunner constructor (multiple constants should be ORed
together).

The DONT_ACCEPT_TRUE_FOR_1 flag disables matches between True/False
and 1/0:

    >>> def f(x):
    ...     '>>> True\n1\n'

    >>> # Without the flag:
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    TestResults(failed=0, attempted=1)

    >>> # With the flag:
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> flags = doctest.DONT_ACCEPT_TRUE_FOR_1
    >>> doctest.DocTestRunner(verbose=False, optionflags=flags).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 2, in f
    Failed example:
        True
    Expected:
        1
    Got:
        True
    TestResults(failed=1, attempted=1)

The DONT_ACCEPT_BLANKLINE flag disables the match between blank lines
and the '<BLANKLINE>' marker:

    >>> def f(x):
    ...     '>>> print "a\\n\\nb"\na\n<BLANKLINE>\nb\n'

    >>> # Without the flag:
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    TestResults(failed=0, attempted=1)

    >>> # With the flag:
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> flags = doctest.DONT_ACCEPT_BLANKLINE
    >>> doctest.DocTestRunner(verbose=False, optionflags=flags).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 2, in f
    Failed example:
        print "a\n\nb"
    Expected:
        a
        <BLANKLINE>
        b
    Got:
        a
    <BLANKLINE>
        b
    TestResults(failed=1, attempted=1)

The NORMALIZE_WHITESPACE flag causes all sequences of whitespace to be
treated as equal:

    >>> def f(x):
    ...     '>>> print 1, 2, 3\n  1   2\n 3'

    >>> # Without the flag:
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 2, in f
    Failed example:
        print 1, 2, 3
    Expected:
          1   2
         3
    Got:
        1 2 3
    TestResults(failed=1, attempted=1)

    >>> # With the flag:
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> flags = doctest.NORMALIZE_WHITESPACE
    >>> doctest.DocTestRunner(verbose=False, optionflags=flags).run(test)
    TestResults(failed=0, attempted=1)

    An example from the docs:
    >>> print range(20) #doctest: +NORMALIZE_WHITESPACE
    [0,   1,  2,  3,  4,  5,  6,  7,  8,  9,
    10,  11, 12, 13, 14, 15, 16, 17, 18, 19]

The ELLIPSIS flag causes ellipsis marker ("...") in the expected
output to match any substring in the actual output:

    >>> def f(x):
    ...     '>>> print range(15)\n[0, 1, 2, ..., 14]\n'

    >>> # Without the flag:
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 2, in f
    Failed example:
        print range(15)
    Expected:
        [0, 1, 2, ..., 14]
    Got:
        [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]
    TestResults(failed=1, attempted=1)

    >>> # With the flag:
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> flags = doctest.ELLIPSIS
    >>> doctest.DocTestRunner(verbose=False, optionflags=flags).run(test)
    TestResults(failed=0, attempted=1)

    ... also matches nothing:

    >>> for i in range(100):
    ...     print i**2, #doctest: +ELLIPSIS
    0 1...4...9 16 ... 36 49 64 ... 9801

    ... can be surprising; e.g., this test passes:

    >>> for i in range(21): #doctest: +ELLIPSIS
    ...     print i,
    0 1 2 ...1...2...0

    Examples from the docs:

    >>> print range(20) # doctest:+ELLIPSIS
    [0, 1, ..., 18, 19]

    >>> print range(20) # doctest: +ELLIPSIS
    ...                 # doctest: +NORMALIZE_WHITESPACE
    [0,    1, ...,   18,    19]

The SKIP flag causes an example to be skipped entirely.  I.e., the
example is not run.  It can be useful in contexts where doctest
examples serve as both documentation and test cases, and an example
should be included for documentation purposes, but should not be
checked (e.g., because its output is random, or depends on resources
which would be unavailable.)  The SKIP flag can also be used for
'commenting out' broken examples.

    >>> import unavailable_resource           # doctest: +SKIP
    >>> unavailable_resource.do_something()   # doctest: +SKIP
    >>> unavailable_resource.blow_up()        # doctest: +SKIP
    Traceback (most recent call last):
        ...
    UncheckedBlowUpError:  Nobody checks me.

    >>> import random
    >>> print random.random() # doctest: +SKIP
    0.721216923889

The REPORT_UDIFF flag causes failures that involve multi-line expected
and actual outputs to be displayed using a unified diff:

    >>> def f(x):
    ...     r'''
    ...     >>> print '\n'.join('abcdefg')
    ...     a
    ...     B
    ...     c
    ...     d
    ...     f
    ...     g
    ...     h
    ...     '''

    >>> # Without the flag:
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 3, in f
    Failed example:
        print '\n'.join('abcdefg')
    Expected:
        a
        B
        c
        d
        f
        g
        h
    Got:
        a
        b
        c
        d
        e
        f
        g
    TestResults(failed=1, attempted=1)

    >>> # With the flag:
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> flags = doctest.REPORT_UDIFF
    >>> doctest.DocTestRunner(verbose=False, optionflags=flags).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 3, in f
    Failed example:
        print '\n'.join('abcdefg')
    Differences (unified diff with -expected +actual):
        @@ -1,7 +1,7 @@
         a
        -B
        +b
         c
         d
        +e
         f
         g
        -h
    TestResults(failed=1, attempted=1)

The REPORT_CDIFF flag causes failures that involve multi-line expected
and actual outputs to be displayed using a context diff:

    >>> # Reuse f() from the REPORT_UDIFF example, above.
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> flags = doctest.REPORT_CDIFF
    >>> doctest.DocTestRunner(verbose=False, optionflags=flags).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 3, in f
    Failed example:
        print '\n'.join('abcdefg')
    Differences (context diff with expected followed by actual):
        ***************
        *** 1,7 ****
          a
        ! B
          c
          d
          f
          g
        - h
        --- 1,7 ----
          a
        ! b
          c
          d
        + e
          f
          g
    TestResults(failed=1, attempted=1)


The REPORT_NDIFF flag causes failures to use the difflib.Differ algorithm
used by the popular ndiff.py utility.  This does intraline difference
marking, as well as interline differences.

    >>> def f(x):
    ...     r'''
    ...     >>> print "a b  c d e f g h i   j k l m"
    ...     a b c d e f g h i j k 1 m
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> flags = doctest.REPORT_NDIFF
    >>> doctest.DocTestRunner(verbose=False, optionflags=flags).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 3, in f
    Failed example:
        print "a b  c d e f g h i   j k l m"
    Differences (ndiff with -expected +actual):
        - a b c d e f g h i j k 1 m
        ?                       ^
        + a b  c d e f g h i   j k l m
        ?     +              ++    ^
    TestResults(failed=1, attempted=1)

The REPORT_ONLY_FIRST_FAILURE suppresses result output after the first
failing example:

    >>> def f(x):
    ...     r'''
    ...     >>> print 1 # first success
    ...     1
    ...     >>> print 2 # first failure
    ...     200
    ...     >>> print 3 # second failure
    ...     300
    ...     >>> print 4 # second success
    ...     4
    ...     >>> print 5 # third failure
    ...     500
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> flags = doctest.REPORT_ONLY_FIRST_FAILURE
    >>> doctest.DocTestRunner(verbose=False, optionflags=flags).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 5, in f
    Failed example:
        print 2 # first failure
    Expected:
        200
    Got:
        2
    TestResults(failed=3, attempted=5)

However, output from `report_start` is not suppressed:

    >>> doctest.DocTestRunner(verbose=True, optionflags=flags).run(test)
    ... # doctest: +ELLIPSIS
    Trying:
        print 1 # first success
    Expecting:
        1
    ok
    Trying:
        print 2 # first failure
    Expecting:
        200
    **********************************************************************
    File ..., line 5, in f
    Failed example:
        print 2 # first failure
    Expected:
        200
    Got:
        2
    TestResults(failed=3, attempted=5)

For the purposes of REPORT_ONLY_FIRST_FAILURE, unexpected exceptions
count as failures:

    >>> def f(x):
    ...     r'''
    ...     >>> print 1 # first success
    ...     1
    ...     >>> raise ValueError(2) # first failure
    ...     200
    ...     >>> print 3 # second failure
    ...     300
    ...     >>> print 4 # second success
    ...     4
    ...     >>> print 5 # third failure
    ...     500
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> flags = doctest.REPORT_ONLY_FIRST_FAILURE
    >>> doctest.DocTestRunner(verbose=False, optionflags=flags).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 5, in f
    Failed example:
        raise ValueError(2) # first failure
    Exception raised:
        ...
        ValueError: 2
    TestResults(failed=3, attempted=5)

New option flags can also be registered, via register_optionflag().  Here
we reach into doctest's internals a bit.

    >>> unlikely = "UNLIKELY_OPTION_NAME"
    >>> unlikely in doctest.OPTIONFLAGS_BY_NAME
    False
    >>> new_flag_value = doctest.register_optionflag(unlikely)
    >>> unlikely in doctest.OPTIONFLAGS_BY_NAME
    True

Before 2.4.4/2.5, registering a name more than once erroneously created
more than one flag value.  Here we verify that's fixed:

    >>> redundant_flag_value = doctest.register_optionflag(unlikely)
    >>> redundant_flag_value == new_flag_value
    True

Clean up.
    >>> del doctest.OPTIONFLAGS_BY_NAME[unlikely]

    """

    def option_directives(): r"""
Tests of `DocTestRunner`'s option directive mechanism.

Option directives can be used to turn option flags on or off for a
single example.  To turn an option on for an example, follow that
example with a comment of the form ``# doctest: +OPTION``:

    >>> def f(x): r'''
    ...     >>> print range(10)       # should fail: no ellipsis
    ...     [0, 1, ..., 9]
    ...
    ...     >>> print range(10)       # doctest: +ELLIPSIS
    ...     [0, 1, ..., 9]
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 2, in f
    Failed example:
        print range(10)       # should fail: no ellipsis
    Expected:
        [0, 1, ..., 9]
    Got:
        [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    TestResults(failed=1, attempted=2)

To turn an option off for an example, follow that example with a
comment of the form ``# doctest: -OPTION``:

    >>> def f(x): r'''
    ...     >>> print range(10)
    ...     [0, 1, ..., 9]
    ...
    ...     >>> # should fail: no ellipsis
    ...     >>> print range(10)       # doctest: -ELLIPSIS
    ...     [0, 1, ..., 9]
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False,
    ...                       optionflags=doctest.ELLIPSIS).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 6, in f
    Failed example:
        print range(10)       # doctest: -ELLIPSIS
    Expected:
        [0, 1, ..., 9]
    Got:
        [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    TestResults(failed=1, attempted=2)

Option directives affect only the example that they appear with; they
do not change the options for surrounding examples:

    >>> def f(x): r'''
    ...     >>> print range(10)       # Should fail: no ellipsis
    ...     [0, 1, ..., 9]
    ...
    ...     >>> print range(10)       # doctest: +ELLIPSIS
    ...     [0, 1, ..., 9]
    ...
    ...     >>> print range(10)       # Should fail: no ellipsis
    ...     [0, 1, ..., 9]
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 2, in f
    Failed example:
        print range(10)       # Should fail: no ellipsis
    Expected:
        [0, 1, ..., 9]
    Got:
        [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    **********************************************************************
    File ..., line 8, in f
    Failed example:
        print range(10)       # Should fail: no ellipsis
    Expected:
        [0, 1, ..., 9]
    Got:
        [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    TestResults(failed=2, attempted=3)

Multiple options may be modified by a single option directive.  They
may be separated by whitespace, commas, or both:

    >>> def f(x): r'''
    ...     >>> print range(10)       # Should fail
    ...     [0, 1,  ...,   9]
    ...     >>> print range(10)       # Should succeed
    ...     ... # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
    ...     [0, 1,  ...,   9]
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 2, in f
    Failed example:
        print range(10)       # Should fail
    Expected:
        [0, 1,  ...,   9]
    Got:
        [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    TestResults(failed=1, attempted=2)

    >>> def f(x): r'''
    ...     >>> print range(10)       # Should fail
    ...     [0, 1,  ...,   9]
    ...     >>> print range(10)       # Should succeed
    ...     ... # doctest: +ELLIPSIS,+NORMALIZE_WHITESPACE
    ...     [0, 1,  ...,   9]
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 2, in f
    Failed example:
        print range(10)       # Should fail
    Expected:
        [0, 1,  ...,   9]
    Got:
        [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    TestResults(failed=1, attempted=2)

    >>> def f(x): r'''
    ...     >>> print range(10)       # Should fail
    ...     [0, 1,  ...,   9]
    ...     >>> print range(10)       # Should succeed
    ...     ... # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
    ...     [0, 1,  ...,   9]
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    ... # doctest: +ELLIPSIS
    **********************************************************************
    File ..., line 2, in f
    Failed example:
        print range(10)       # Should fail
    Expected:
        [0, 1,  ...,   9]
    Got:
        [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    TestResults(failed=1, attempted=2)

The option directive may be put on the line following the source, as
long as a continuation prompt is used:

    >>> def f(x): r'''
    ...     >>> print range(10)
    ...     ... # doctest: +ELLIPSIS
    ...     [0, 1, ..., 9]
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    TestResults(failed=0, attempted=1)

For examples with multi-line source, the option directive may appear
at the end of any line:

    >>> def f(x): r'''
    ...     >>> for x in range(10): # doctest: +ELLIPSIS
    ...     ...     print x,
    ...     0 1 2 ... 9
    ...
    ...     >>> for x in range(10):
    ...     ...     print x,        # doctest: +ELLIPSIS
    ...     0 1 2 ... 9
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    TestResults(failed=0, attempted=2)

If more than one line of an example with multi-line source has an
option directive, then they are combined:

    >>> def f(x): r'''
    ...     Should fail (option directive not on the last line):
    ...         >>> for x in range(10): # doctest: +ELLIPSIS
    ...         ...     print x,        # doctest: +NORMALIZE_WHITESPACE
    ...         0  1    2...9
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> doctest.DocTestRunner(verbose=False).run(test)
    TestResults(failed=0, attempted=1)

It is an error to have a comment of the form ``# doctest:`` that is
*not* followed by words of the form ``+OPTION`` or ``-OPTION``, where
``OPTION`` is an option that has been registered with
`register_option`:

    >>> # Error: Option not registered
    >>> s = '>>> print 12   #doctest: +BADOPTION'
    >>> test = doctest.DocTestParser().get_doctest(s, {}, 's', 's.py', 0)
    Traceback (most recent call last):
    ValueError: line 1 of the doctest for s has an invalid option: '+BADOPTION'

    >>> # Error: No + or - prefix
    >>> s = '>>> print 12   #doctest: ELLIPSIS'
    >>> test = doctest.DocTestParser().get_doctest(s, {}, 's', 's.py', 0)
    Traceback (most recent call last):
    ValueError: line 1 of the doctest for s has an invalid option: 'ELLIPSIS'

It is an error to use an option directive on a line that contains no
source:

    >>> s = '>>> # doctest: +ELLIPSIS'
    >>> test = doctest.DocTestParser().get_doctest(s, {}, 's', 's.py', 0)
    Traceback (most recent call last):
    ValueError: line 0 of the doctest for s has an option directive on a line with no example: '# doctest: +ELLIPSIS'

    """

    def test_unicode_output(self): r"""

Check that unicode output works:

    >>> u'\xe9'
    u'\xe9'

If we return unicode, SpoofOut's buf variable becomes automagically
converted to unicode. This means all subsequent output becomes converted
to unicode, and if the output contains non-ascii characters that failed.
It used to be that this state change carried on between tests, meaning
tests would fail if unicode has been output previously in the testrun.
This test tests that this is no longer so:

    >>> print u'abc'
    abc

And the…