Add context.HandlerNames()

[lggomez]

This PR adds a HandlerNames method which returns all registered handles for the context in descending order

[codecov]

Codecov Report

Merging #1729 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1729      +/-   ##
==========================================
+ Coverage   98.49%   98.49%   +<.01%     
==========================================
  Files          41       41              
  Lines        2054     2059       +5     
==========================================
+ Hits         2023     2028       +5     
  Misses         19       19              
  Partials       12       12

Impacted Files	Coverage Δ
context.go	98.32% <100%> (+0.02%)	⬆️

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[thinkerou]

when use HandlerNames? thanks!

[lggomez]

Hi @thinkerou! at work we have dozens of large services which include both ad-hoc middlewares and base ones which come from an internal framework that dynamicly injects metrics and infrastructure related middlewares upon app initialization

In some cases and during testing, problems may arise due to invalid or wrong configurations on containers that result in different middleware pipelines being applied to those instances. In one specific case, we had an unhandled panic on a goroutine that was bringing down the service, and this helped to discard configuration issues on both the app server and the framework configuration (we've had those in the past) before I moved on to review the affected service implementation

tl;dr: It's useful to dump all the active handlers when diagnosing production issues

[thinkerou]

Thanks! LGTM.