bpo-38659: [Enum] add _simple_enum decorator (GH-25497)

add:

* `_simple_enum` decorator to transform a normal class into an enum
* `_test_simple_enum` function to compare
* `_old_convert_` to enable checking `_convert_` generated enums

`_simple_enum` takes a normal class and converts it into an enum:

    @simple_enum(Enum)
    class Color:
        RED = 1
        GREEN = 2
        BLUE = 3

`_old_convert_` works much like` _convert_` does, using the original logic:

    # in a test file
    import socket, enum
    CheckedAddressFamily = enum._old_convert_(
            enum.IntEnum, 'AddressFamily', 'socket',
            lambda C: C.isupper() and C.startswith('AF_'),
            source=_socket,
            )

`_test_simple_enum` takes a traditional enum and a simple enum and
compares the two:

    # in the REPL or the same module as Color
    class CheckedColor(Enum):
        RED = 1
        GREEN = 2
        BLUE = 3

    _test_simple_enum(CheckedColor, Color)

    _test_simple_enum(CheckedAddressFamily, socket.AddressFamily)

Any important differences will raise a TypeError

1 files changed, 145 insertions, 0 deletions

diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
index 5fb45924e50..438c2ebbb3d 100644
--- a/Lib/test/test_httplib.py
+++ b/Lib/test/test_httplib.py
@@ -1,3 +1,4 @@
+import enum
 import errno
 from http import client, HTTPStatus
 import io
@@ -524,6 +525,150 @@ class BasicTest(TestCase):
         # see issue40084
         self.assertTrue({'description', 'name', 'phrase', 'value'} <= set(dir(HTTPStatus(404))))
 
+    def test_simple_httpstatus(self):
+        class CheckedHTTPStatus(enum.IntEnum):
+            """HTTP status codes and reason phrases
+
+            Status codes from the following RFCs are all observed:
+
+                * RFC 7231: Hypertext Transfer Protocol (HTTP/1.1), obsoletes 2616
+                * RFC 6585: Additional HTTP Status Codes
+                * RFC 3229: Delta encoding in HTTP
+                * RFC 4918: HTTP Extensions for WebDAV, obsoletes 2518
+                * RFC 5842: Binding Extensions to WebDAV
+                * RFC 7238: Permanent Redirect
+                * RFC 2295: Transparent Content Negotiation in HTTP
+                * RFC 2774: An HTTP Extension Framework
+                * RFC 7725: An HTTP Status Code to Report Legal Obstacles
+                * RFC 7540: Hypertext Transfer Protocol Version 2 (HTTP/2)
+                * RFC 2324: Hyper Text Coffee Pot Control Protocol (HTCPCP/1.0)
+                * RFC 8297: An HTTP Status Code for Indicating Hints
+                * RFC 8470: Using Early Data in HTTP
+            """
+            def __new__(cls, value, phrase, description=''):
+                obj = int.__new__(cls, value)
+                obj._value_ = value
+
+                obj.phrase = phrase
+                obj.description = description
+                return obj
+            # informational
+            CONTINUE = 100, 'Continue', 'Request received, please continue'
+            SWITCHING_PROTOCOLS = (101, 'Switching Protocols',
+                    'Switching to new protocol; obey Upgrade header')
+            PROCESSING = 102, 'Processing'
+            EARLY_HINTS = 103, 'Early Hints'
+            # success
+            OK = 200, 'OK', 'Request fulfilled, document follows'
+            CREATED = 201, 'Created', 'Document created, URL follows'
+            ACCEPTED = (202, 'Accepted',
+                'Request accepted, processing continues off-line')
+            NON_AUTHORITATIVE_INFORMATION = (203,
+                'Non-Authoritative Information', 'Request fulfilled from cache')
+            NO_CONTENT = 204, 'No Content', 'Request fulfilled, nothing follows'
+            RESET_CONTENT = 205, 'Reset Content', 'Clear input form for further input'
+            PARTIAL_CONTENT = 206, 'Partial Content', 'Partial content follows'
+            MULTI_STATUS = 207, 'Multi-Status'
+            ALREADY_REPORTED = 208, 'Already Reported'
+            IM_USED = 226, 'IM Used'
+            # redirection
+            MULTIPLE_CHOICES = (300, 'Multiple Choices',
+                'Object has several resources -- see URI list')
+            MOVED_PERMANENTLY = (301, 'Moved Permanently',
+                'Object moved permanently -- see URI list')
+            FOUND = 302, 'Found', 'Object moved temporarily -- see URI list'
+            SEE_OTHER = 303, 'See Other', 'Object moved -- see Method and URL list'
+            NOT_MODIFIED = (304, 'Not Modified',
+                'Document has not changed since given time')
+            USE_PROXY = (305, 'Use Proxy',
+                'You must use proxy specified in Location to access this resource')
+            TEMPORARY_REDIRECT = (307, 'Temporary Redirect',
+                'Object moved temporarily -- see URI list')
+            PERMANENT_REDIRECT = (308, 'Permanent Redirect',
+                'Object moved permanently -- see URI list')
+            # client error
+            BAD_REQUEST = (400, 'Bad Request',
+                'Bad request syntax or unsupported method')
+            UNAUTHORIZED = (401, 'Unauthorized',
+                'No permission -- see authorization schemes')
+            PAYMENT_REQUIRED = (402, 'Payment Required',
+                'No payment -- see charging schemes')
+            FORBIDDEN = (403, 'Forbidden',
+                'Request forbidden -- authorization will not help')
+            NOT_FOUND = (404, 'Not Found',
+                'Nothing matches the given URI')
+            METHOD_NOT_ALLOWED = (405, 'Method Not Allowed',
+                'Specified method is invalid for this resource')
+            NOT_ACCEPTABLE = (406, 'Not Acceptable',
+                'URI not available in preferred format')
+            PROXY_AUTHENTICATION_REQUIRED = (407,
+                'Proxy Authentication Required',
+                'You must authenticate with this proxy before proceeding')
+            REQUEST_TIMEOUT = (408, 'Request Timeout',
+                'Request timed out; try again later')
+            CONFLICT = 409, 'Conflict', 'Request conflict'
+            GONE = (410, 'Gone',
+                'URI no longer exists and has been permanently removed')
+            LENGTH_REQUIRED = (411, 'Length Required',
+                'Client must specify Content-Length')
+            PRECONDITION_FAILED = (412, 'Precondition Failed',
+                'Precondition in headers is false')
+            REQUEST_ENTITY_TOO_LARGE = (413, 'Request Entity Too Large',
+                'Entity is too large')
+            REQUEST_URI_TOO_LONG = (414, 'Request-URI Too Long',
+                'URI is too long')
+            UNSUPPORTED_MEDIA_TYPE = (415, 'Unsupported Media Type',
+                'Entity body in unsupported format')
+            REQUESTED_RANGE_NOT_SATISFIABLE = (416,
+                'Requested Range Not Satisfiable',
+                'Cannot satisfy request range')
+            EXPECTATION_FAILED = (417, 'Expectation Failed',
+                'Expect condition could not be satisfied')
+            IM_A_TEAPOT = (418, 'I\'m a Teapot',
+                'Server refuses to brew coffee because it is a teapot.')
+            MISDIRECTED_REQUEST = (421, 'Misdirected Request',
+                'Server is not able to produce a response')
+            UNPROCESSABLE_ENTITY = 422, 'Unprocessable Entity'
+            LOCKED = 423, 'Locked'
+            FAILED_DEPENDENCY = 424, 'Failed Dependency'
+            TOO_EARLY = 425, 'Too Early'
+            UPGRADE_REQUIRED = 426, 'Upgrade Required'
+            PRECONDITION_REQUIRED = (428, 'Precondition Required',
+                'The origin server requires the request to be conditional')
+            TOO_MANY_REQUESTS = (429, 'Too Many Requests',
+                'The user has sent too many requests in '
+                'a given amount of time ("rate limiting")')
+            REQUEST_HEADER_FIELDS_TOO_LARGE = (431,
+                'Request Header Fields Too Large',
+                'The server is unwilling to process the request because its header '
+                'fields are too large')
+            UNAVAILABLE_FOR_LEGAL_REASONS = (451,
+                'Unavailable For Legal Reasons',
+                'The server is denying access to the '
+                'resource as a consequence of a legal demand')
+            # server errors
+            INTERNAL_SERVER_ERROR = (500, 'Internal Server Error',
+                'Server got itself in trouble')
+            NOT_IMPLEMENTED = (501, 'Not Implemented',
+                'Server does not support this operation')
+            BAD_GATEWAY = (502, 'Bad Gateway',
+                'Invalid responses from another server/proxy')
+            SERVICE_UNAVAILABLE = (503, 'Service Unavailable',
+                'The server cannot process the request due to a high load')
+            GATEWAY_TIMEOUT = (504, 'Gateway Timeout',
+                'The gateway server did not receive a timely response')
+            HTTP_VERSION_NOT_SUPPORTED = (505, 'HTTP Version Not Supported',
+                'Cannot fulfill request')
+            VARIANT_ALSO_NEGOTIATES = 506, 'Variant Also Negotiates'
+            INSUFFICIENT_STORAGE = 507, 'Insufficient Storage'
+            LOOP_DETECTED = 508, 'Loop Detected'
+            NOT_EXTENDED = 510, 'Not Extended'
+            NETWORK_AUTHENTICATION_REQUIRED = (511,
+                'Network Authentication Required',
+                'The client needs to authenticate to gain network access')
+        enum._test_simple_enum(CheckedHTTPStatus, HTTPStatus)
+
+
     def test_status_lines(self):
         # Test HTTP status lines