Testing Guide: unnecessary comment
Testing Guide: unnecessary comment

This has been around as far back as I can
[see](https://github.com/rails/rails/blob/5137d03cc5b2a5f0820bdcf11b0fffe5bf461470/guides/source/testing.md).

No need to specify the obvious.

[ci skip]

illacceptanything/illacceptanything,rafaelfranca/omg-rails,schuetzm/rails,palkan/rails,esparta/rails,esparta/rails,flanger001/rails,repinel/rails,tgxworld/rails,jeremy/rails,yawboakye/rails,yahonda/rails,Envek/rails,starknx/rails,Edouard-chin/rails,georgeclaghorn/rails,arunagw/rails,vipulnsward/rails,Envek/rails,yalab/rails,joonyou/rails,betesh/rails,repinel/rails,mechanicles/rails,yalab/rails,mohitnatoo/rails,EmmaB/rails-1,flanger001/rails,betesh/rails,rails/rails,printercu/rails,MSP-Greg/rails,Edouard-chin/rails,printercu/rails,shioyama/rails,Erol/rails,kddeisz/rails,tgxworld/rails,arunagw/rails,mohitnatoo/rails,jeremy/rails,yalab/rails,BlakeWilliams/rails,illacceptanything/illacceptanything,rafaelfranca/omg-rails,baerjam/rails,Stellenticket/rails,aditya-kapoor/rails,lcreid/rails,Vasfed/rails,georgeclaghorn/rails,tjschuck/rails,georgeclaghorn/rails,yawboakye/rails,illacceptanything/illacceptanything,Edouard-chin/rails,notapatch/rails,rails/rails,georgeclaghorn/rails,fabianoleittes/rails,BlakeWilliams/rails,Edouard-chin/rails,tjschuck/rails,rafaelfranca/omg-rails,Erol/rails,lcreid/rails,iainbeeston/rails,yahonda/rails,kddeisz/rails,eileencodes/rails,joonyou/rails,EmmaB/rails-1,kmcphillips/rails,illacceptanything/illacceptanything,bogdanvlviv/rails,prathamesh-sonpatki/rails,yawboakye/rails,iainbeeston/rails,gauravtiwari/rails,fabianoleittes/rails,joonyou/rails,tgxworld/rails,schuetzm/rails,printercu/rails,vipulnsward/rails,vipulnsward/rails,eileencodes/rails,Envek/rails,baerjam/rails,MSP-Greg/rails,rails/rails,illacceptanything/illacceptanything,joonyou/rails,Stellenticket/rails,tgxworld/rails,iainbeeston/rails,repinel/rails,gauravtiwari/rails,gauravtiwari/rails,bogdanvlviv/rails,shioyama/rails,esparta/rails,yhirano55/rails,BlakeWilliams/rails,prathamesh-sonpatki/rails,utilum/rails,utilum/rails,jeremy/rails,illacceptanything/illacceptanything,EmmaB/rails-1,notapatch/rails,utilum/rails,mohitnatoo/rails,notapatch/rails,shioyama/rails,mechanicles/rails,flanger001/rails,aditya-kapoor/rails,baerjam/rails,shioyama/rails,bogdanvlviv/rails,yawboakye/rails,baerjam/rails,tjschuck/rails,yalab/rails,aditya-kapoor/rails,palkan/rails,starknx/rails,MSP-Greg/rails,Erol/rails,MSP-Greg/rails,Erol/rails,mohitnatoo/rails,palkan/rails,Vasfed/rails,tjschuck/rails,kddeisz/rails,rails/rails,Vasfed/rails,esparta/rails,illacceptanything/illacceptanything,printercu/rails,schuetzm/rails,Stellenticket/rails,betesh/rails,yhirano55/rails,flanger001/rails,mechanicles/rails,kmcphillips/rails,lcreid/rails,yhirano55/rails,betesh/rails,illacceptanything/illacceptanything,starknx/rails,kddeisz/rails,Stellenticket/rails,yahonda/rails,schuetzm/rails,illacceptanything/illacceptanything,aditya-kapoor/rails,yhirano55/rails,prathamesh-sonpatki/rails,bogdanvlviv/rails,jeremy/rails,Vasfed/rails,notapatch/rails,mechanicles/rails,BlakeWilliams/rails,illacceptanything/illacceptanything,repinel/rails,vipulnsward/rails,illacceptanything/illacceptanything,lcreid/rails,kmcphillips/rails,illacceptanything/illacceptanything,illacceptanything/illacceptanything,yahonda/rails,prathamesh-sonpatki/rails,fabianoleittes/rails,palkan/rails,iainbeeston/rails,illacceptanything/illacceptanything,utilum/rails,eileencodes/rails,arunagw/rails,Envek/rails,arunagw/rails,illacceptanything/illacceptanything,eileencodes/rails,fabianoleittes/rails,kmcphillips/rails