Compression threshold changed in Express 4 middleware, breaks test

[hampelm]

Gzip compression is handled by compression in Express 4. By default, it only compresses responses >=1kb. The theory is that compressing smaller responses might actually increase the size.

The compression test we have now fails because the response is 14-ish bytes, and doesn't get compressed. Is there something we know will be more than 1kb in a test environment? Should we drop the test?

I tested manually with a larger request and compression is working.

[prashtx]

It might be worth setting the threshold lower (or removing it for JSON responses).

A GeoJSON FeatureCollection with a single feature should put us just above the point where gzip starts to help rather than hurt. For those small responses, we're spending unnecessary CPU time doing the gzipping. But for a response under 1 kB, gzip should be pretty fast. The API is also not typically very pressed for CPU. Our mobile clients are pressed for bandwidth, though, so a compression regression could lead to a significant client performance degradation.

[hampelm]

I'm getting an ambiguous error when disabling the threshold entirely or setting it very low (eg 10B). I'll do a test on a clean app to see if it's reproducible.