73 lines
2.6 KiB
Erlang
73 lines
2.6 KiB
Erlang
%%--------------------------------------------------------------------
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%% Copyright (c) 2020-2021 EMQ Technologies Co., Ltd. All Rights Reserved.
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%%
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%% Licensed under the Apache License, Version 2.0 (the "License");
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%% you may not use this file except in compliance with the License.
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%% You may obtain a copy of the License at
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%%
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%% http://www.apache.org/licenses/LICENSE-2.0
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%%
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%% Unless required by applicable law or agreed to in writing, software
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%% distributed under the License is distributed on an "AS IS" BASIS,
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%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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%% See the License for the specific language governing permissions and
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%% limitations under the License.
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%%--------------------------------------------------------------------
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-module(prop_emqx_base62).
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-include_lib("proper/include/proper.hrl").
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%%--------------------------------------------------------------------
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%% Properties
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%%--------------------------------------------------------------------
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prop_symmetric() ->
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?FORALL(Data, raw_data(),
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begin
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Encoded = emqx_base62:encode(Data),
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to_binary(Data) =:= emqx_base62:decode(Encoded)
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end).
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prop_size() ->
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?FORALL(Data, binary(),
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begin
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Encoded = emqx_base62:encode(Data),
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base62_size(Data, Encoded)
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end).
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%%--------------------------------------------------------------------
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%% Helpers
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%%--------------------------------------------------------------------
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to_binary(Data) when is_list(Data) ->
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unicode:characters_to_binary(Data);
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to_binary(Data) when is_integer(Data) ->
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integer_to_binary(Data);
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to_binary(Data) when is_binary(Data) ->
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Data.
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base62_size(Data, Encoded) ->
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DataSize = erlang:size(Data),
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EncodedSize = erlang:size(Encoded),
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case (DataSize * 8 rem 6) of
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0 ->
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%% Due to the particularity of base 62, 3 bytes data maybe encoded
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%% as 4 bytes data or 5 bytes data, the encode size maybe in the
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%% range between DataSize*4/3 and DataSize*8/3
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RangeStart = DataSize div 3 * 4,
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RangeEnd = DataSize div 3 * 8,
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EncodedSize >= RangeStart andalso EncodedSize =< RangeEnd;
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_Rem ->
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RangeStart = DataSize * 8 div 6 + 1,
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RangeEnd = DataSize * 8 div 6 * 2 + 1,
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EncodedSize >= RangeStart andalso EncodedSize =< RangeEnd
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end.
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%%--------------------------------------------------------------------
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%% Generators
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%%--------------------------------------------------------------------
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raw_data() ->
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oneof([integer(), string(), binary()]).
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