Add tests for `Overcommit::HookContext::PostCommit`
Add tests for `Overcommit::HookContext::PostCommit`

Change-Id: I05ddef5679719d4814c0deb4a77c2bf1a64c431b
Reviewed-on: http://gerrit.causes.com/46926
Reviewed-by: Shane da Silva <67fb7bfe39f841b16a1f86d3928acc568d12c716@brigade.com>
Tested-by: Shane da Silva <67fb7bfe39f841b16a1f86d3928acc568d12c716@brigade.com>

gnagel/overcommit,TheSooth/overcommit,oxocode/overcommit,blech75/overcommit,blech75/overcommit,oxocode/overcommit,gnagel/overcommit,TheSooth/overcommit