How can I access the current URI in a view during testing?

I have a shared view component that changes state based on the current URI. I'm currently accessing that information via request.env['PATH_INFO'], as this seems to be the convention as far as I can tell. However, when running unit tests, this always seems to be nil. This is an issue, because it causes any view with this component to explode.

Setting @request.env['PATH_INFO'] in the body of the test doesn't work, and I'm glad it doesn't because that would be hideous.

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How can I access the current URI within a view or controller during testing?

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_{I'm using vanilla Rails unit testing, so answers that don't require me to change my testing framework would be much appreciated.}