Check if stream is seekable when downloading object to path

[gedimin45]

The destination path can also be php://output, then the file is streamed directly to output. However, that is not seekable and an exception is thrown.
Perhaps the method name is not accurate anymore then - something like downloadToPath might be more appropriate.

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[gedimin45]

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[jdpedrie]

Thanks for the PR! I'll leave the question of the method name to @dwsupplee as he's the lead on our Storage implementation, but if you don't mind, would you please add a test to Google\Cloud\Tests\Storage\StorageObjectTest showing the correct behavior when streaming to php://output?

You can capture and assert against the output using ob_start() and ob_get_clean(). :)

You should be fine copying most of the body of Google\Cloud\Tests\Storage\StorageObject::testDownloadsToFile() and updating the assertion as necessary.

If you're not familiar with PHPUnit or have any questions please let us know. One of us would be happy to assist.

[dwsupplee]

Thanks for the PR - downloadToPath sounds a like solid suggestion to me. @Ged15 would you like to include that change in this PR as well? :)

[gedimin45]

@jdpedrie @dwsupplee please take a look at #199. I believe it introduces a more flexible approach in retrieving StorageObject contents.

[dwsupplee]

I really like the direction in #199. Mind if I close this out @Ged15?

[gedimin45]

I can do it as well :)