Unit testing the use of metrics

[ar...@google.com]

Hi prometheus-developers,

Is there any way to unit test that my code is setting its metrics the way that I expect? Effectively this would just mean being able to read the value of the metric after running some code that is supposed to set it, I don't see any obvious public way to access the value of a metric in the client_golang library.

Thanks,
Alex

[Julius Volz]

Hey Alex,

Great question! Of course testing metric values should really be supported in some way (especially for jobs that basically only transform metrics from a third-party system into Prometheus metrics), but there were some initial disagreements about how exactly this should work. IIRC these were now mostly resolved. Björn (CCed) can probably best share the current plans for that.

Cheers,

Julius

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[Björn Rabenstein]

Hi Alex,

The issue you are looking for is
https://github.com/prometheus/client_golang/issues/58 .

We had a lot of discussions around this, and I shall be working on it
quite soon.

The state-of-the-art work around so far is to call the Write() method
of your metrics-to-be-tested and then inspect the protobuf object.

See https://github.com/prometheus/haproxy_exporter/blob/master/haproxy_exporter_test.go#L39
to see how that works in practice. It's not as bad as it sounds, and
it will soon be addressed...

Sorry for that...