Method unshift

Tests/Libraries/AsyncStreams/AsyncStreamsTest.cpp:484–555

}

void SC::AsyncStreamsTest::unshift()
{
    AsyncBufferView::ID bufferID;
    Span<char>          data;
    AsyncBufferView     buffers[1];
    Buffer              buffer;
    SC_TEST_EXPECT(buffer.resizeWithoutInitializing(123));
    buffers[0] = buffer.toSpan();
    buffers[0].setReusable(true);

    AsyncBuffersPool pool;
    pool.setBuffers(buffers);

    struct TestReadableStream : public AsyncReadableStream
    {
        int  step    = 0;
        bool success = true;

        virtual Result asyncRead() override
        {
            step++;
            // We do nothing here, just waiting for push
            return Result(true);
        }
    };
    TestReadableStream           readable;
    AsyncReadableStream::Request requests[3];
    readable.setReadQueue(requests); // Capacity 2
    SC_TEST_EXPECT(readable.init(pool));

    SC_TEST_EXPECT(readable.getBuffersPool().requestNewBuffer(123, bufferID, data));

    // 1. Manually unshift a buffer
    char content[] = "123";
    memcpy(data.data(), content, 3);
    readable.getBuffersPool().setNewBufferSize(bufferID, 3);
    SC_TRUST_RESULT(readable.unshift(bufferID));
    // Release our reference so that the stream is the only owner and can recycle it after emission
    pool.unrefBuffer(bufferID);

    // 2. Start reading, it should immediately receive the unshifted buffer
    SC_TEST_EXPECT(readable.eventData.addListener(
        [&readable](AsyncBufferView::ID id)
        {
            Span<const char> readData;
            SC_TRUST_RESULT(readable.getBuffersPool().getReadableData(id, readData));
            StringView str = StringView(readData, false, StringEncoding::Ascii);
            if (str != "123")
                readable.success = false;
            // Should be received before asyncRead is even called or right at start
            if (readable.step != 0)
                readable.success = false;
        }));

    SC_TRUST_RESULT(readable.start());
    SC_TEST_EXPECT(readable.success);

    // Cleanup to allow re-use of buffer for next check