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AK: Demonstrate surprising ByteBuffer behavior

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This seems to be because ByteBuffer implements 'operator bool', and C++
considers bool to be an integer type. Thus, when trying to find a way to
evaluate '==', it attempts integer promotion, which in turn finds 'operator bool'.

This explains why all non-empty buffers seem to be equal, but different from the
empty one. Also, why comparison seems to be implemented.
This commit is contained in:
Ben Wiederhake 2020-08-17 00:33:50 +02:00 committed by Andreas Kling
parent 8925ad3fa0
commit 901ed9b85d
Notes: sideshowbarker 2024-07-19 03:18:12 +09:00 
Author: https://github.com/BenWiederhake
Commit: https://github.com/SerenityOS/serenity/commit/901ed9b85d5
Pull-request: https://github.com/SerenityOS/serenity/pull/3262
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AK/Tests/TestByteBuffer.cpp Normal file
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/*
* Copyright (c) 2020, the SerenityOS developers.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/TestSuite.h>
#include <AK/ByteBuffer.h>
TEST_CASE(equality_operator)
{
ByteBuffer a = ByteBuffer::copy("Hello, world", 7);
ByteBuffer b = ByteBuffer::copy("Hello, friend", 7);
// `a` and `b` are both "Hello, ".
ByteBuffer c = ByteBuffer::copy("asdf", 4);
ByteBuffer d;
EXPECT_EQ(a == a, true);
EXPECT_EQ(a == b, true);
EXPECT_EQ(a == c, false);
EXPECT_EQ(a == d, false);
EXPECT_EQ(b == a, true);
EXPECT_EQ(b == b, true);
EXPECT_EQ(b == c, false);
EXPECT_EQ(b == d, false);
EXPECT_EQ(c == a, false);
EXPECT_EQ(c == b, false);
EXPECT_EQ(c == c, true);
EXPECT_EQ(c == d, false);
EXPECT_EQ(d == a, false);
EXPECT_EQ(d == b, false);
EXPECT_EQ(d == c, false);
EXPECT_EQ(d == d, true);
}
TEST_CASE(other_operators)
{
ByteBuffer a = ByteBuffer::copy("Hello, world", 7);
ByteBuffer b = ByteBuffer::copy("Hello, friend", 7);
// `a` and `b` are both "Hello, ".
ByteBuffer c = ByteBuffer::copy("asdf", 4);
ByteBuffer d;
EXPECT_EQ(a < a, true);
EXPECT_EQ(a <= b, true);
EXPECT_EQ(a >= c, false);
EXPECT_EQ(a > d, false);
}
TEST_MAIN(ByteBuffer)