flask/tests/test_helpers.py

# -*- coding: utf-8 -*-
"""
    tests.helpers
    ~~~~~~~~~~~~~~~~~~~~~~~

    Various helpers.

    :copyright: 2010 Pallets
    :license: BSD-3-Clause
"""

import datetime
import os
import uuid

import pytest
from werkzeug.datastructures import Range
from werkzeug.exceptions import BadRequest, NotFound
from werkzeug.http import (
    http_date, parse_cache_control_header,
    parse_options_header
)

import flask
from flask import json
from flask._compat import StringIO, text_type
from flask.helpers import get_debug_flag, get_env


def has_encoding(name):
    try:
        import codecs
        codecs.lookup(name)
        return True
    except LookupError:
        return False


class FixedOffset(datetime.tzinfo):
    """Fixed offset in hours east from UTC.

    This is a slight adaptation of the ``FixedOffset`` example found in
    https://docs.python.org/2.7/library/datetime.html.
    """

    def __init__(self, hours, name):
        self.__offset = datetime.timedelta(hours=hours)
        self.__name = name

    def utcoffset(self, dt):
        return self.__offset

    def tzname(self, dt):
        return self.__name

    def dst(self, dt):
        return datetime.timedelta()


class TestJSON(object):
    @pytest.mark.parametrize('value', (
        1, 't', True, False, None,
        [], [1, 2, 3],
        {}, {'foo': u'🐍'},
    ))
    @pytest.mark.parametrize('encoding', (
        'utf-8', 'utf-8-sig',
        'utf-16-le', 'utf-16-be', 'utf-16',
        'utf-32-le', 'utf-32-be', 'utf-32',
    ))
    def test_detect_encoding(self, value, encoding):
        data = json.dumps(value).encode(encoding)
        assert json.detect_encoding(data) == encoding
        assert json.loads(data) == value

    def test_ignore_cached_json(self, app):
        with app.test_request_context('/', method='POST', data='malformed',
                                      content_type='application/json'):
            assert flask.request.get_json(silent=True, cache=True) is None
            with pytest.raises(BadRequest):
                flask.request.get_json(silent=False, cache=False)

    def test_different_silent_on_bad_request(self, app):
        with app.test_request_context(
                '/', method='POST', data='malformed',
                content_type='application/json'):
            assert flask.request.get_json(silent=True) is None
            with pytest.raises(BadRequest):
                flask.request.get_json(silent=False)

    def test_different_silent_on_normal_request(self, app):
        with app.test_request_context('/', method='POST', json={'foo': 'bar'}):
            silent_rv = flask.request.get_json(silent=True)
            normal_rv = flask.request.get_json(silent=False)
            assert silent_rv is normal_rv
            assert normal_rv['foo'] == 'bar'

    def test_post_empty_json_adds_exception_to_response_content_in_debug(self, app, client):
        app.config['DEBUG'] = True
        app.config['TRAP_BAD_REQUEST_ERRORS'] = False

        @app.route('/json', methods=['POST'])
        def post_json():
            flask.request.get_json()
            return None

        rv = client.post('/json', data=None, content_type='application/json')
        assert rv.status_code == 400
        assert b'Failed to decode JSON object' in rv.data

    def test_post_empty_json_wont_add_exception_to_response_if_no_debug(self, app, client):
        app.config['DEBUG'] = False
        app.config['TRAP_BAD_REQUEST_ERRORS'] = False

        @app.route('/json', methods=['POST'])
        def post_json():
            flask.request.get_json()
            return None

        rv = client.post('/json', data=None, content_type='application/json')
        assert rv.status_code == 400
        assert b'Failed to decode JSON object' not in rv.data

    def test_json_bad_requests(self, app, client):

        @app.route('/json', methods=['POST'])
        def return_json():
            return flask.jsonify(foo=text_type(flask.request.get_json()))

        rv = client.post('/json', data='malformed', content_type='application/json')
        assert rv.status_code == 400

    def test_json_custom_mimetypes(self, app, client):

        @app.route('/json', methods=['POST'])
        def return_json():
            return flask.request.get_json()

        rv = client.post('/json', data='"foo"', content_type='application/x+json')
        assert rv.data == b'foo'

    @pytest.mark.parametrize('test_value,expected', [(True, '"\\u2603"'), (False, u'"\u2603"')])
    def test_json_as_unicode(self, test_value, expected, app, app_ctx):

        app.config['JSON_AS_ASCII'] = test_value
        rv = flask.json.dumps(u'\N{SNOWMAN}')
        assert rv == expected

    def test_json_dump_to_file(self, app, app_ctx):
        test_data = {'name': 'Flask'}
        out = StringIO()

        flask.json.dump(test_data, out)
        out.seek(0)
        rv = flask.json.load(out)
        assert rv == test_data

    @pytest.mark.parametrize('test_value', [0, -1, 1, 23, 3.14, 's', "longer string", True, False, None])
    def test_jsonify_basic_types(self, test_value, app, client):
        """Test jsonify with basic types."""

        url = '/jsonify_basic_types'
        app.add_url_rule(url, url, lambda x=test_value: flask.jsonify(x))
        rv = client.get(url)
        assert rv.mimetype == 'application/json'
        assert flask.json.loads(rv.data) == test_value

    def test_jsonify_dicts(self, app, client):
        """Test jsonify with dicts and kwargs unpacking."""
        d = {'a': 0, 'b': 23, 'c': 3.14, 'd': 't',
             'e': 'Hi', 'f': True, 'g': False,
             'h': ['test list', 10, False],
             'i': {'test': 'dict'}}

        @app.route('/kw')
        def return_kwargs():
            return flask.jsonify(**d)

        @app.route('/dict')
        def return_dict():
            return flask.jsonify(d)

        for url in '/kw', '/dict':
            rv = client.get(url)
            assert rv.mimetype == 'application/json'
            assert flask.json.loads(rv.data) == d

    def test_jsonify_arrays(self, app, client):
        """Test jsonify of lists and args unpacking."""
        l = [
            0, 42, 3.14, 't', 'hello', True, False,
            ['test list', 2, False],
            {'test': 'dict'}
        ]

        @app.route('/args_unpack')
        def return_args_unpack():
            return flask.jsonify(*l)

        @app.route('/array')
        def return_array():
            return flask.jsonify(l)

        for url in '/args_unpack', '/array':
            rv = client.get(url)
            assert rv.mimetype == 'application/json'
            assert flask.json.loads(rv.data) == l

    def test_jsonify_date_types(self, app, client):
        """Test jsonify with datetime.date and datetime.datetime types."""
        test_dates = (
            datetime.datetime(1973, 3, 11, 6, 30, 45),
            datetime.date(1975, 1, 5)
        )

        for i, d in enumerate(test_dates):
            url = '/datetest{0}'.format(i)
            app.add_url_rule(url, str(i), lambda val=d: flask.jsonify(x=val))
            rv = client.get(url)
            assert rv.mimetype == 'application/json'
            assert flask.json.loads(rv.data)['x'] == http_date(d.timetuple())

    @pytest.mark.parametrize('tz', (('UTC', 0), ('PST', -8), ('KST', 9)))
    def test_jsonify_aware_datetimes(self, tz):
        """Test if aware datetime.datetime objects are converted into GMT."""
        tzinfo = FixedOffset(hours=tz[1], name=tz[0])
        dt = datetime.datetime(2017, 1, 1, 12, 34, 56, tzinfo=tzinfo)
        gmt = FixedOffset(hours=0, name='GMT')
        expected = dt.astimezone(gmt).strftime('"%a, %d %b %Y %H:%M:%S %Z"')
        assert flask.json.JSONEncoder().encode(dt) == expected

    def test_jsonify_uuid_types(self, app, client):
        """Test jsonify with uuid.UUID types"""

        test_uuid = uuid.UUID(bytes=b'\xDE\xAD\xBE\xEF' * 4)
        url = '/uuid_test'
        app.add_url_rule(url, url, lambda: flask.jsonify(x=test_uuid))

        rv = client.get(url)

        rv_x = flask.json.loads(rv.data)['x']
        assert rv_x == str(test_uuid)
        rv_uuid = uuid.UUID(rv_x)
        assert rv_uuid == test_uuid

    def test_json_attr(self, app, client):

        @app.route('/add', methods=['POST'])
        def add():
            json = flask.request.get_json()
            return text_type(json['a'] + json['b'])

        rv = client.post('/add', data=flask.json.dumps({'a': 1, 'b': 2}),
                         content_type='application/json')
        assert rv.data == b'3'

    def test_template_escaping(self, app, req_ctx):
        render = flask.render_template_string
        rv = flask.json.htmlsafe_dumps('</script>')
        assert rv == u'"\\u003c/script\\u003e"'
        assert type(rv) == text_type
        rv = render('{{ "</script>"|tojson }}')
        assert rv == '"\\u003c/script\\u003e"'
        rv = render('{{ "<\0/script>"|tojson }}')
        assert rv == '"\\u003c\\u0000/script\\u003e"'
        rv = render('{{ "<!--<script>"|tojson }}')
        assert rv == '"\\u003c!--\\u003cscript\\u003e"'
        rv = render('{{ "&"|tojson }}')
        assert rv == '"\\u0026"'
        rv = render('{{ "\'"|tojson }}')
        assert rv == '"\\u0027"'
        rv = render("<a ng-data='{{ data|tojson }}'></a>",
                    data={'x': ["foo", "bar", "baz'"]})
        assert rv == '<a ng-data=\'{"x": ["foo", "bar", "baz\\u0027"]}\'></a>'

    def test_json_customization(self, app, client):
        class X(object):
            def __init__(self, val):
                self.val = val

        class MyEncoder(flask.json.JSONEncoder):
            def default(self, o):
                if isinstance(o, X):
                    return '<%d>' % o.val
                return flask.json.JSONEncoder.default(self, o)

        class MyDecoder(flask.json.JSONDecoder):
            def __init__(self, *args, **kwargs):
                kwargs.setdefault('object_hook', self.object_hook)
                flask.json.JSONDecoder.__init__(self, *args, **kwargs)

            def object_hook(self, obj):
                if len(obj) == 1 and '_foo' in obj:
                    return X(obj['_foo'])
                return obj

        app.json_encoder = MyEncoder
        app.json_decoder = MyDecoder

        @app.route('/', methods=['POST'])
        def index():
            return flask.json.dumps(flask.request.get_json()['x'])

        rv = client.post('/', data=flask.json.dumps({
            'x': {'_foo': 42}
        }), content_type='application/json')
        assert rv.data == b'"<42>"'

    def test_blueprint_json_customization(self, app, client):
        class X(object):
            def __init__(self, val):
                self.val = val

        class MyEncoder(flask.json.JSONEncoder):
            def default(self, o):
                if isinstance(o, X):
                    return '<%d>' % o.val

                return flask.json.JSONEncoder.default(self, o)

        class MyDecoder(flask.json.JSONDecoder):
            def __init__(self, *args, **kwargs):
                kwargs.setdefault('object_hook', self.object_hook)
                flask.json.JSONDecoder.__init__(self, *args, **kwargs)

            def object_hook(self, obj):
                if len(obj) == 1 and '_foo' in obj:
                    return X(obj['_foo'])

                return obj

        bp = flask.Blueprint('bp', __name__)
        bp.json_encoder = MyEncoder
        bp.json_decoder = MyDecoder

        @bp.route('/bp', methods=['POST'])
        def index():
            return flask.json.dumps(flask.request.get_json()['x'])

        app.register_blueprint(bp)

        rv = client.post('/bp', data=flask.json.dumps({
            'x': {'_foo': 42}
        }), content_type='application/json')
        assert rv.data == b'"<42>"'

    def test_modified_url_encoding(self, app, client):
        class ModifiedRequest(flask.Request):
            url_charset = 'euc-kr'

        app.request_class = ModifiedRequest
        app.url_map.charset = 'euc-kr'

        @app.route('/')
        def index():
            return flask.request.args['foo']

        rv = client.get(u'/?foo=정상처리'.encode('euc-kr'))
        assert rv.status_code == 200
        assert rv.data == u'정상처리'.encode('utf-8')

    if not has_encoding('euc-kr'):
        test_modified_url_encoding = None

    def test_json_key_sorting(self, app, client):
        app.debug = True

        assert app.config['JSON_SORT_KEYS'] == True
        d = dict.fromkeys(range(20), 'foo')

        @app.route('/')
        def index():
            return flask.jsonify(values=d)

        rv = client.get('/')
        lines = [x.strip() for x in rv.data.strip().decode('utf-8').splitlines()]
        sorted_by_str = [
            '{',
            '"values": {',
            '"0": "foo",',
            '"1": "foo",',
            '"10": "foo",',
            '"11": "foo",',
            '"12": "foo",',
            '"13": "foo",',
            '"14": "foo",',
            '"15": "foo",',
            '"16": "foo",',
            '"17": "foo",',
            '"18": "foo",',
            '"19": "foo",',
            '"2": "foo",',
            '"3": "foo",',
            '"4": "foo",',
            '"5": "foo",',
            '"6": "foo",',
            '"7": "foo",',
            '"8": "foo",',
            '"9": "foo"',
            '}',
            '}'
        ]
        sorted_by_int = [
            '{',
            '"values": {',
            '"0": "foo",',
            '"1": "foo",',
            '"2": "foo",',
            '"3": "foo",',
            '"4": "foo",',
            '"5": "foo",',
            '"6": "foo",',
            '"7": "foo",',
            '"8": "foo",',
            '"9": "foo",',
            '"10": "foo",',
            '"11": "foo",',
            '"12": "foo",',
            '"13": "foo",',
            '"14": "foo",',
            '"15": "foo",',
            '"16": "foo",',
            '"17": "foo",',
            '"18": "foo",',
            '"19": "foo"',
            '}',
            '}'
        ]

        try:
            assert lines == sorted_by_int
        except AssertionError:
            assert lines == sorted_by_str


class TestSendfile(object):
    def test_send_file_regular(self, app, req_ctx):
        rv = flask.send_file('static/index.html')
        assert rv.direct_passthrough
        assert rv.mimetype == 'text/html'
        with app.open_resource('static/index.html') as f:
            rv.direct_passthrough = False
            assert rv.data == f.read()
        rv.close()

    def test_send_file_xsendfile(self, app, req_ctx):
        app.use_x_sendfile = True
        rv = flask.send_file('static/index.html')
        assert rv.direct_passthrough
        assert 'x-sendfile' in rv.headers
        assert rv.headers['x-sendfile'] == \
               os.path.join(app.root_path, 'static/index.html')
        assert rv.mimetype == 'text/html'
        rv.close()

    def test_send_file_last_modified(self, app, client):
        last_modified = datetime.datetime(1999, 1, 1)

        @app.route('/')
        def index():
            return flask.send_file(StringIO("party like it's"),
                                   last_modified=last_modified,
                                   mimetype='text/plain')

        rv = client.get('/')
        assert rv.last_modified == last_modified

    def test_send_file_object_without_mimetype(self, app, req_ctx):
        with pytest.raises(ValueError) as excinfo:
            flask.send_file(StringIO("LOL"))
        assert 'Unable to infer MIME-type' in str(excinfo)
        assert 'no filename is available' in str(excinfo)

        flask.send_file(StringIO("LOL"), attachment_filename='filename')

    def test_send_file_object(self, app, req_ctx):
        with open(os.path.join(app.root_path, 'static/index.html'), mode='rb') as f:
            rv = flask.send_file(f, mimetype='text/html')
            rv.direct_passthrough = False
            with app.open_resource('static/index.html') as f:
                assert rv.data == f.read()
            assert rv.mimetype == 'text/html'
            rv.close()

        app.use_x_sendfile = True

        with open(os.path.join(app.root_path, 'static/index.html')) as f:
            rv = flask.send_file(f, mimetype='text/html')
            assert rv.mimetype == 'text/html'
            assert 'x-sendfile' not in rv.headers
            rv.close()

        app.use_x_sendfile = False
        f = StringIO('Test')
        rv = flask.send_file(f, mimetype='application/octet-stream')
        rv.direct_passthrough = False
        assert rv.data == b'Test'
        assert rv.mimetype == 'application/octet-stream'
        rv.close()

        class PyStringIO(object):
            def __init__(self, *args, **kwargs):
                self._io = StringIO(*args, **kwargs)

            def __getattr__(self, name):
                return getattr(self._io, name)

        f = PyStringIO('Test')
        f.name = 'test.txt'
        rv = flask.send_file(f, attachment_filename=f.name)
        rv.direct_passthrough = False
        assert rv.data == b'Test'
        assert rv.mimetype == 'text/plain'
        rv.close()

        f = StringIO('Test')
        rv = flask.send_file(f, mimetype='text/plain')
        rv.direct_passthrough = False
        assert rv.data == b'Test'
        assert rv.mimetype == 'text/plain'
        rv.close()

        app.use_x_sendfile = True

        f = StringIO('Test')
        rv = flask.send_file(f, mimetype='text/html')
        assert 'x-sendfile' not in rv.headers
        rv.close()

    @pytest.mark.skipif(
        not callable(getattr(Range, 'to_content_range_header', None)),
        reason="not implemented within werkzeug"
    )
    def test_send_file_range_request(self, app, client):
        @app.route('/')
        def index():
            return flask.send_file('static/index.html', conditional=True)

        rv = client.get('/', headers={'Range': 'bytes=4-15'})
        assert rv.status_code == 206
        with app.open_resource('static/index.html') as f:
            assert rv.data == f.read()[4:16]
        rv.close()

        rv = client.get('/', headers={'Range': 'bytes=4-'})
        assert rv.status_code == 206
        with app.open_resource('static/index.html') as f:
            assert rv.data == f.read()[4:]
        rv.close()

        rv = client.get('/', headers={'Range': 'bytes=4-1000'})
        assert rv.status_code == 206
        with app.open_resource('static/index.html') as f:
            assert rv.data == f.read()[4:]
        rv.close()

        rv = client.get('/', headers={'Range': 'bytes=-10'})
        assert rv.status_code == 206
        with app.open_resource('static/index.html') as f:
            assert rv.data == f.read()[-10:]
        rv.close()

        rv = client.get('/', headers={'Range': 'bytes=1000-'})
        assert rv.status_code == 416
        rv.close()

        rv = client.get('/', headers={'Range': 'bytes=-'})
        assert rv.status_code == 416
        rv.close()

        rv = client.get('/', headers={'Range': 'somethingsomething'})
        assert rv.status_code == 416
        rv.close()

        last_modified = datetime.datetime.utcfromtimestamp(os.path.getmtime(
            os.path.join(app.root_path, 'static/index.html'))).replace(
            microsecond=0)

        rv = client.get('/', headers={'Range': 'bytes=4-15',
                                      'If-Range': http_date(last_modified)})
        assert rv.status_code == 206
        rv.close()

        rv = client.get('/', headers={'Range': 'bytes=4-15', 'If-Range': http_date(
            datetime.datetime(1999, 1, 1))})
        assert rv.status_code == 200
        rv.close()

    @pytest.mark.skipif(
        not callable(getattr(Range, 'to_content_range_header', None)),
        reason="not implemented within werkzeug"
    )
    def test_send_file_range_request_xsendfile_invalid(self, app, client):
        # https://github.com/pallets/flask/issues/2526
        app.use_x_sendfile = True

        @app.route('/')
        def index():
            return flask.send_file('static/index.html', conditional=True)

        rv = client.get('/', headers={'Range': 'bytes=1000-'})
        assert rv.status_code == 416
        rv.close()

    def test_attachment(self, app, req_ctx):
        app = flask.Flask(__name__)
        with app.test_request_context():
            with open(os.path.join(app.root_path, 'static/index.html')) as f:
                rv = flask.send_file(f, as_attachment=True,
                                     attachment_filename='index.html')
                value, options = \
                    parse_options_header(rv.headers['Content-Disposition'])
                assert value == 'attachment'
                rv.close()

        with open(os.path.join(app.root_path, 'static/index.html')) as f:
            rv = flask.send_file(f, as_attachment=True,
                                 attachment_filename='index.html')
            value, options = \
                parse_options_header(rv.headers['Content-Disposition'])
            assert value == 'attachment'
            assert options['filename'] == 'index.html'
            assert 'filename*' not in rv.headers['Content-Disposition']
            rv.close()

        rv = flask.send_file('static/index.html', as_attachment=True)
        value, options = parse_options_header(rv.headers['Content-Disposition'])
        assert value == 'attachment'
        assert options['filename'] == 'index.html'
        rv.close()

        rv = flask.send_file(StringIO('Test'), as_attachment=True,
                             attachment_filename='index.txt',
                             add_etags=False)
        assert rv.mimetype == 'text/plain'
        value, options = parse_options_header(rv.headers['Content-Disposition'])
        assert value == 'attachment'
        assert options['filename'] == 'index.txt'
        rv.close()

    @pytest.mark.usefixtures('req_ctx')
    @pytest.mark.parametrize(('filename', 'ascii', 'utf8'), (
        ('index.html', 'index.html', False),
        (u'Ñandú／pingüino.txt', '"Nandu/pinguino.txt"',
        '%C3%91and%C3%BA%EF%BC%8Fping%C3%BCino.txt'),
        (u'Vögel.txt', 'Vogel.txt', 'V%C3%B6gel.txt'),
        # Native string not marked as Unicode on Python 2
        ('tést.txt', 'test.txt', 't%C3%A9st.txt'),
    ))
    def test_attachment_filename_encoding(self, filename, ascii, utf8):
        rv = flask.send_file('static/index.html', as_attachment=True, attachment_filename=filename)
        rv.close()
        content_disposition = rv.headers['Content-Disposition']
        assert 'filename=%s' % ascii in content_disposition
        if utf8:
            assert "filename*=UTF-8''" + utf8 in content_disposition
        else:
            assert "filename*=UTF-8''" not in content_disposition

    def test_static_file(self, app, req_ctx):
        # default cache timeout is 12 hours

        # Test with static file handler.
        rv = app.send_static_file('index.html')
        cc = parse_cache_control_header(rv.headers['Cache-Control'])
        assert cc.max_age == 12 * 60 * 60
        rv.close()
        # Test again with direct use of send_file utility.
        rv = flask.send_file('static/index.html')
        cc = parse_cache_control_header(rv.headers['Cache-Control'])
        assert cc.max_age == 12 * 60 * 60
        rv.close()
        app.config['SEND_FILE_MAX_AGE_DEFAULT'] = 3600

        # Test with static file handler.
        rv = app.send_static_file('index.html')
        cc = parse_cache_control_header(rv.headers['Cache-Control'])
        assert cc.max_age == 3600
        rv.close()
        # Test again with direct use of send_file utility.
        rv = flask.send_file('static/index.html')
        cc = parse_cache_control_header(rv.headers['Cache-Control'])
        assert cc.max_age == 3600
        rv.close()

        class StaticFileApp(flask.Flask):
            def get_send_file_max_age(self, filename):
                return 10

        app = StaticFileApp(__name__)
        with app.test_request_context():
            # Test with static file handler.
            rv = app.send_static_file('index.html')
            cc = parse_cache_control_header(rv.headers['Cache-Control'])
            assert cc.max_age == 10
            rv.close()
            # Test again with direct use of send_file utility.
            rv = flask.send_file('static/index.html')
            cc = parse_cache_control_header(rv.headers['Cache-Control'])
            assert cc.max_age == 10
            rv.close()

    def test_send_from_directory(self, app, req_ctx):
        app.root_path = os.path.join(os.path.dirname(__file__),
                                     'test_apps', 'subdomaintestmodule')
        rv = flask.send_from_directory('static', 'hello.txt')
        rv.direct_passthrough = False
        assert rv.data.strip() == b'Hello Subdomain'
        rv.close()

    def test_send_from_directory_bad_request(self, app, req_ctx):
        app.root_path = os.path.join(os.path.dirname(__file__),
                                     'test_apps', 'subdomaintestmodule')

        with pytest.raises(BadRequest):
            flask.send_from_directory('static', 'bad\x00')


class TestUrlFor(object):
    def test_url_for_with_anchor(self, app, req_ctx):

        @app.route('/')
        def index():
            return '42'

        assert flask.url_for('index', _anchor='x y') == '/#x%20y'

    def test_url_for_with_scheme(self, app, req_ctx):

        @app.route('/')
        def index():
            return '42'

        assert flask.url_for('index', _external=True, _scheme='https') == 'https://localhost/'

    def test_url_for_with_scheme_not_external(self, app, req_ctx):

        @app.route('/')
        def index():
            return '42'

        pytest.raises(ValueError,
                      flask.url_for,
                      'index',
                      _scheme='https')

    def test_url_for_with_alternating_schemes(self, app, req_ctx):

        @app.route('/')
        def index():
            return '42'

        assert flask.url_for('index', _external=True) == 'http://localhost/'
        assert flask.url_for('index', _external=True, _scheme='https') == 'https://localhost/'
        assert flask.url_for('index', _external=True) == 'http://localhost/'

    def test_url_with_method(self, app, req_ctx):
        from flask.views import MethodView

        class MyView(MethodView):
            def get(self, id=None):
                if id is None:
                    return 'List'
                return 'Get %d' % id

            def post(self):
                return 'Create'

        myview = MyView.as_view('myview')
        app.add_url_rule('/myview/', methods=['GET'],
                         view_func=myview)
        app.add_url_rule('/myview/<int:id>', methods=['GET'],
                         view_func=myview)
        app.add_url_rule('/myview/create', methods=['POST'],
                         view_func=myview)

        assert flask.url_for('myview', _method='GET') == '/myview/'
        assert flask.url_for('myview', id=42, _method='GET') == '/myview/42'
        assert flask.url_for('myview', _method='POST') == '/myview/create'


class TestNoImports(object):
    """Test Flasks are created without import.

    Avoiding ``__import__`` helps create Flask instances where there are errors
    at import time.  Those runtime errors will be apparent to the user soon
    enough, but tools which build Flask instances meta-programmatically benefit
    from a Flask which does not ``__import__``.  Instead of importing to
    retrieve file paths or metadata on a module or package, use the pkgutil and
    imp modules in the Python standard library.
    """

    def test_name_with_import_error(self, modules_tmpdir):
        modules_tmpdir.join('importerror.py').write('raise NotImplementedError()')
        try:
            flask.Flask('importerror')
        except NotImplementedError:
            assert False, 'Flask(import_name) is importing import_name.'


class TestStreaming(object):
    def test_streaming_with_context(self, app, client):

        @app.route('/')
        def index():
            def generate():
                yield 'Hello '
                yield flask.request.args['name']
                yield '!'

            return flask.Response(flask.stream_with_context(generate()))

        rv = client.get('/?name=World')
        assert rv.data == b'Hello World!'

    def test_streaming_with_context_as_decorator(self, app, client):

        @app.route('/')
        def index():
            @flask.stream_with_context
            def generate(hello):
                yield hello
                yield flask.request.args['name']
                yield '!'

            return flask.Response(generate('Hello '))

        rv = client.get('/?name=World')
        assert rv.data == b'Hello World!'

    def test_streaming_with_context_and_custom_close(self, app, client):
        called = []

        class Wrapper(object):
            def __init__(self, gen):
                self._gen = gen

            def __iter__(self):
                return self

            def close(self):
                called.append(42)

            def __next__(self):
                return next(self._gen)

            next = __next__

        @app.route('/')
        def index():
            def generate():
                yield 'Hello '
                yield flask.request.args['name']
                yield '!'

            return flask.Response(flask.stream_with_context(
                Wrapper(generate())))

        rv = client.get('/?name=World')
        assert rv.data == b'Hello World!'
        assert called == [42]

    def test_stream_keeps_session(self, app, client):
        @app.route('/')
        def index():
            flask.session['test'] = 'flask'

            @flask.stream_with_context
            def gen():
                yield flask.session['test']

            return flask.Response(gen())

        rv = client.get('/')
        assert rv.data == b'flask'


class TestSafeJoin(object):
    def test_safe_join(self):
        # Valid combinations of *args and expected joined paths.
        passing = (
            (('a/b/c',), 'a/b/c'),
            (('/', 'a/', 'b/', 'c/'), '/a/b/c'),
            (('a', 'b', 'c'), 'a/b/c'),
            (('/a', 'b/c'), '/a/b/c'),
            (('a/b', 'X/../c'), 'a/b/c'),
            (('/a/b', 'c/X/..'), '/a/b/c'),
            # If last path is '' add a slash
            (('/a/b/c', ''), '/a/b/c/'),
            # Preserve dot slash
            (('/a/b/c', './'), '/a/b/c/.'),
            (('a/b/c', 'X/..'), 'a/b/c/.'),
            # Base directory is always considered safe
            (('../', 'a/b/c'), '../a/b/c'),
            (('/..',), '/..'),
        )

        for args, expected in passing:
            assert flask.safe_join(*args) == expected

    def test_safe_join_exceptions(self):
        # Should raise werkzeug.exceptions.NotFound on unsafe joins.
        failing = (
            # path.isabs and ``..'' checks
            ('/a', 'b', '/c'),
            ('/a', '../b/c'),
            ('/a', '..', 'b/c'),
            # Boundaries violations after path normalization
            ('/a', 'b/../b/../../c'),
            ('/a', 'b', 'c/../..'),
            ('/a', 'b/../../c'),
        )

        for args in failing:
            with pytest.raises(NotFound):
                print(flask.safe_join(*args))

class TestHelpers(object):

    @pytest.mark.parametrize('debug, expected_flag, expected_default_flag', [
        ('', False, False),
        ('0', False, False),
        ('False', False, False),
        ('No', False, False),
        ('True', True, True)
    ])
    def test_get_debug_flag(self, monkeypatch, debug, expected_flag, expected_default_flag):
        monkeypatch.setenv('FLASK_DEBUG', debug)
        if expected_flag is None:
            assert get_debug_flag() is None
        else:
            assert get_debug_flag() == expected_flag
        assert get_debug_flag() == expected_default_flag

    @pytest.mark.parametrize('env, ref_env, debug', [
        ('', 'production', False),
        ('production', 'production', False),
        ('development', 'development', True),
        ('other', 'other', False),
    ])
    def test_get_env(self, monkeypatch, env, ref_env, debug):
        monkeypatch.setenv('FLASK_ENV', env)
        assert get_debug_flag() == debug
        assert get_env() == ref_env

    def test_make_response(self):
        app = flask.Flask(__name__)
        with app.test_request_context():
            rv = flask.helpers.make_response()
            assert rv.status_code == 200
            assert rv.mimetype == 'text/html'

            rv = flask.helpers.make_response('Hello')
            assert rv.status_code == 200
            assert rv.data == b'Hello'
            assert rv.mimetype == 'text/html'