How to use the requests3.basics.str function in requests3

def test_non_str_basicauth(self, username, password):
        """Ensure we only allow string or bytes values for basicauth"""
        with pytest.raises(TypeError) as e:
            requests.auth._basic_auth_str(username, password)
        assert 'must be of type str or bytes' in str(e)

def tell(self):
                return 0

            def __iter__(self):
                return

        data = BadFileObj('the data')

        prep = requests.Request(
            'GET', 'http://example.com', data=data
        ).prepare(
        )
        assert prep._body_position == 0
        with pytest.raises(UnrewindableBodyError) as e:
            requests.utils.rewind_body(prep)
        assert 'Unable to rewind request body' in str(e)

def test_non_prepared_request_error(self, s):
        req = requests.Request(u('POST'), '/')
        with pytest.raises(ValueError) as e:
            s.send(req)
        assert str(e.value) == 'You can only send PreparedRequests.'

def test_http_error(self):
        error = requests.exceptions.HTTPError()
        assert not error.response
        response = requests.Response()
        error = requests.exceptions.HTTPError(response=response)
        assert error.response == response
        error = requests.exceptions.HTTPError('message', response=response)
        assert str(error) == 'message'
        assert error.response == response

def tell(self):
                raise OSError()

            def __iter__(self):
                return

        data = BadFileObj('the data')
        prep = requests.Request(
            'GET', 'http://example.com', data=data
        ).prepare(
        )
        assert prep._body_position is not None
        with pytest.raises(UnrewindableBodyError) as e:
            requests.utils.rewind_body(prep)
        assert 'Unable to rewind request body' in str(e)

def test_urllib3_pool_connection_closed(httpbin, s):
    s.mount('http://', HTTPAdapter(pool_connections=0, pool_maxsize=0))
    try:
        s.get(httpbin('status/200'))
    except ConnectionError as e:
        assert u"Pool is closed." in str(e)

def prepare_url(self, url, params, validate=False):
        """Prepares the given HTTP URL."""
        # : Accept objects that have string representations.
        #: We're unable to blindly call unicode/str functions
        #: as this will include the bytestring indicator (b'')
        #: on python 3.x.
        #: https://github.com/requests/requests/pull/2238
        if isinstance(url, bytes):
            url = url.decode('utf8')
        else:
            url = str(url)
        # Ignore any leading and trailing whitespace characters.
        url = url.strip()
        # Don't do any URL preparation for non-HTTP schemes like `mailto`,
        # `data` etc to work around exceptions from `url_parse`, which
        # handles RFC 3986 only.
        if ':' in url and not url.lower().startswith('http'):
            self.url = url
            return

        # Support for unicode domain names and paths.
        try:
            uri = rfc3986.urlparse(url)
            if validate:
                rfc3986.normalize_uri(url)
        except rfc3986.exceptions.RFC3986Exception:
            raise InvalidURL(f"Invalid URL {url!r}: URL is imporoper.")

return str('')

        # Fallback to auto-detected encoding.
        if self.encoding is None:
            encoding = self.apparent_encoding
        # Decode unicode from given encoding.
        try:
            content = str(self.content, encoding, errors='replace')
        except (LookupError, TypeError):
            # A LookupError is raised if the encoding was not found which could
            # indicate a misspelling or similar mistake.
            #
            # A TypeError can be raised if encoding is None
            #
            # So we try blindly encoding.
            content = str(await self.content, errors='replace')
        return content

headers, following RFC 2616 to the letter. If you can take advantage of
        non-HTTP knowledge to make a better guess at the encoding, you should
        set ``r.encoding`` appropriately before accessing this property.
        """
        # Try charset from content-type
        content = None
        encoding = self.encoding
        if not await self.content:
            return str('')

        # Fallback to auto-detected encoding.
        if self.encoding is None:
            encoding = self.apparent_encoding
        # Decode unicode from given encoding.
        try:
            content = str(self.content, encoding, errors='replace')
        except (LookupError, TypeError):
            # A LookupError is raised if the encoding was not found which could
            # indicate a misspelling or similar mistake.
            #
            # A TypeError can be raised if encoding is None
            #
            # So we try blindly encoding.
            content = str(await self.content, errors='replace')
        return content