[RTM] Improve zlib stream check

[ausi]

Fixes #38

[leofeyer]

I still think it is wrong to test the object instantiation.

if (null === $zlibSupport) {
    $zlibSupport = false;

    if (\in_array('compress.zlib', stream_get_wrappers(), true)) {
        $reader = new XMLReader();

        if (true ===  @$reader->open('compress.zlib://data:text/xml,<x/>')) {
            $zlibSupport = true;
        }

        @$reader->close();
    }
}

[ausi]

Your code doesn’t test the read() method. How about this?

if (null === $zlibSupport) {
    $reader = new XMLReader();
    $zlibSupport =
        \in_array('compress.zlib', stream_get_wrappers(), true)
        && true === @$reader->open('compress.zlib://data:text/xml,<x/>')
        && true === @$reader->read()
    ;
}

[leofeyer]

The test file is 'compress.zlib://data:text/xml,<x/>'. How can this be opened but not read?

[ausi]

For example compress.zlib://data:text/xml, can be opened but not read.

[leofeyer]

Yes, but that is not our test string, is it?

[ausi]

No, but if the compress.zlib wrapper doesn’t work correctly it could currupt the <x/> and this would result in read() returning false.

[leofeyer]

Very unlikely but then just keep it as it is.