Improve test coverage and add standard flag support

[stephen-soltesz]

This change is 

[coveralls]

Pull Request Test Coverage Report for Build 96

• 32 of 32 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+26.4%) to 90.657%

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Totals
Change from base Build 85:	26.4%
Covered Lines:	262
Relevant Lines:	289

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💛 - Coveralls

[stephen-soltesz]

Note: I've seen the error for both :9990 and :9393 (either server socket may fail to be available soon enough).

[pboothe]

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cmd/github_receiver/main_test.go, line 59 at r2 (raw file):

Previously, stephen-soltesz (Stephen Soltesz) wrote…

O_o -- so, I'm a bit baffled here. I was deceived by my workstation - there is a race. But, I don't see where it's coming from. The error reported: `Could not start metric server(error: listen tcp :9990: bind: address already in use)`. This implies to me that the process has not called or completed the underlying socket close. But, I'm calling http `Server.Close` which closes all listeners, which should release the socket before returning from the `defer` statements that call `Server.Close`. But, by observation, it takes some additional time after. The delay works around that, but why isn't the shutdown / close complete after returning from `Server.Close`?

Use ":0" for your listen addresses.