Assert against result object instead of recorder

[jotaen]

I noticed that there is a subtle issue in the test setup, which could potentially lead to false positive test results.

According to the documentation of httptest.ResponseRecorder (see their example), you are supposed to run the test assertions against the result object returned by recorder.Result(), rather than against the recorder object itself.

The recorder object basically tracks all interactions of the request handlers with the response. However, this may be different from what the HTTP server actually sends out to the client.

One such edge-case scenario is when you try to set response headers after having flushed out the response headers. In this case, any attempt to modify the headers via res.Headers().Set() will silently result in a no-op. The response object issued by rec.Result() correctly reflects that, whereas the recorder object itself incorrectly yields the seemingly set header.

• Before the fix: the tests all pass, but in reality, no Content-Type header was set
• After the fix: the tests fail

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[jotaen]

I have read the CLA Document and I hereby sign the CLA

[jotaen]

recheck

[mtlynch]

Thanks, @jotaen!

This is another situation where I'm glad to learn this gotcha but sad thinking about the work ahead of me in correcting this mistake in the 5000 places I've made it in other projects. 😂