Do not use the same test class in different tests
Do not use the same test class in different tests

This fixes the following warnings.

```
actionmailer/test/base_test.rb:272: warning: method redefined; discarding old welcome
actionmailer/test/base_test.rb:260: warning: previous definition of welcome was here
```

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