Method test

autotest/cpp/test_cpl.cpp:3858–3894

template <class T> struct TesterDelta
{
    static void test(const char *dtypeOption)
    {
        const auto pCompressor = CPLGetCompressor("delta");
        ASSERT_TRUE(pCompressor);
        if (pCompressor == nullptr)
            return;
        const auto pDecompressor = CPLGetDecompressor("delta");
        ASSERT_TRUE(pDecompressor);
        if (pDecompressor == nullptr)
            return;

        const T tabIn[] = {static_cast<T>(-2), 3, 1};
        T tabCompress[3];
        T tabOut[3];
        const char *const apszOptions[] = {dtypeOption, nullptr};

        void *outPtr = &tabCompress[0];
        size_t outSize = sizeof(tabCompress);
        ASSERT_TRUE(pCompressor->pfnFunc(&tabIn[0], sizeof(tabIn), &outPtr,
                                         &outSize, apszOptions,
                                         pCompressor->user_data));
        ASSERT_EQ(outSize, sizeof(tabCompress));

        // ASSERT_EQ(tabCompress[0], 2);
        // ASSERT_EQ(tabCompress[1], 1);
        // ASSERT_EQ(tabCompress[2], -2);

        outPtr = &tabOut[0];
        outSize = sizeof(tabOut);
        ASSERT_TRUE(pDecompressor->pfnFunc(&tabCompress[0], sizeof(tabCompress),
                                           &outPtr, &outSize, apszOptions,
                                           pDecompressor->user_data));
        ASSERT_EQ(outSize, sizeof(tabOut));
        ASSERT_EQ(tabOut[0], tabIn[0]);
        ASSERT_EQ(tabOut[1], tabIn[1]);
        ASSERT_EQ(tabOut[2], tabIn[2]);
    }
};

// Test delta compressor/decompressor