DataReductionProxyNetworkDelegateTest(1) has many tests for the interaction between DataReductionProxyNetoworkDelegate and various metrics reported through UMA. The tests are difficult to maintain because many(>15) UMA variables can be updated by a single function, but most of the tests only look for a couple of them, while failing to verify that all of the variables are in their expected state.

I propose adding a helper function called CheckHistograms(std::vector<HistogramTest>) which will check all histograms against a baseline, except the histograms specified in the vector. CheckHistograms might need a couple other options around response length and compression, but this would provide two benefits to maintainers of DRPNDT

- New histograms would need to be added to the baseline in CheckHistograms, providing test coverage in all existing test cases.

- Tests would only need to define expectations for histograms that deviate from the norm, reducing the lines a developer needs to read to understand the purpose of each test.






1) https://cs.chromium.org/chromium/src/components/data_reduction_proxy/core/browser/data_reduction_proxy_network_delegate_unittest.cc?l=946&rcl=1e0e596c3bc385c0f16fa8d83eccb18d066219de