messages: Add test coverage for IRC mirroring code path.
messages: Add test coverage for IRC mirroring code path.

jphilipsen05/zulip,shubhamdhama/zulip,brockwhittaker/zulip,dhcrzf/zulip,dhcrzf/zulip,rht/zulip,christi3k/zulip,hackerkid/zulip,timabbott/zulip,susansls/zulip,brockwhittaker/zulip,hackerkid/zulip,ryanbackman/zulip,synicalsyntax/zulip,brainwane/zulip,Galexrt/zulip,jrowan/zulip,synicalsyntax/zulip,synicalsyntax/zulip,dawran6/zulip,j831/zulip,jphilipsen05/zulip,j831/zulip,kou/zulip,showell/zulip,j831/zulip,christi3k/zulip,dawran6/zulip,tommyip/zulip,punchagan/zulip,vabs22/zulip,kou/zulip,souravbadami/zulip,shubhamdhama/zulip,showell/zulip,timabbott/zulip,kou/zulip,jainayush975/zulip,zulip/zulip,samatdav/zulip,souravbadami/zulip,timabbott/zulip,brainwane/zulip,andersk/zulip,kou/zulip,susansls/zulip,JPJPJPOPOP/zulip,timabbott/zulip,j831/zulip,mahim97/zulip,synicalsyntax/zulip,Galexrt/zulip,dawran6/zulip,eeshangarg/zulip,punchagan/zulip,aakash-cr7/zulip,vabs22/zulip,andersk/zulip,rht/zulip,rishig/zulip,tommyip/zulip,vaidap/zulip,dhcrzf/zulip,dhcrzf/zulip,mahim97/zulip,brainwane/zulip,ryanbackman/zulip,jainayush975/zulip,tommyip/zulip,dhcrzf/zulip,aakash-cr7/zulip,tommyip/zulip,punchagan/zulip,zulip/zulip,verma-varsha/zulip,jrowan/zulip,verma-varsha/zulip,SmartPeople/zulip,tommyip/zulip,samatdav/zulip,vaidap/zulip,zulip/zulip,showell/zulip,hackerkid/zulip,PhilSk/zulip,vaidap/zulip,jainayush975/zulip,verma-varsha/zulip,PhilSk/zulip,rishig/zulip,showell/zulip,SmartPeople/zulip,JPJPJPOPOP/zulip,blaze225/zulip,jphilipsen05/zulip,dattatreya303/zulip,amanharitsh123/zulip,jainayush975/zulip,eeshangarg/zulip,souravbadami/zulip,brainwane/zulip,hackerkid/zulip,rishig/zulip,andersk/zulip,punchagan/zulip,dhcrzf/zulip,brainwane/zulip,JPJPJPOPOP/zulip,dawran6/zulip,jackrzhang/zulip,j831/zulip,brockwhittaker/zulip,synicalsyntax/zulip,Galexrt/zulip,brockwhittaker/zulip,tommyip/zulip,christi3k/zulip,jackrzhang/zulip,JPJPJPOPOP/zulip,showell/zulip,timabbott/zulip,Galexrt/zulip,rht/zulip,susansls/zulip,brockwhittaker/zulip,amanharitsh123/zulip,synicalsyntax/zulip,shubhamdhama/zulip,shubhamdhama/zulip,blaze225/zulip,JPJPJPOPOP/zulip,aakash-cr7/zulip,zulip/zulip,souravbadami/zulip,vaidap/zulip,dattatreya303/zulip,mahim97/zulip,SmartPeople/zulip,verma-varsha/zulip,dattatreya303/zulip,tommyip/zulip,blaze225/zulip,jphilipsen05/zulip,hackerkid/zulip,jackrzhang/zulip,verma-varsha/zulip,zulip/zulip,SmartPeople/zulip,vabs22/zulip,jphilipsen05/zulip,dattatreya303/zulip,souravbadami/zulip,jackrzhang/zulip,blaze225/zulip,dattatreya303/zulip,timabbott/zulip,vabs22/zulip,rht/zulip,souravbadami/zulip,punchagan/zulip,rishig/zulip,showell/zulip,rht/zulip,JPJPJPOPOP/zulip,rht/zulip,eeshangarg/zulip,jphilipsen05/zulip,eeshangarg/zulip,kou/zulip,ryanbackman/zulip,dhcrzf/zulip,andersk/zulip,aakash-cr7/zulip,mahim97/zulip,brainwane/zulip,vaidap/zulip,jrowan/zulip,andersk/zulip,showell/zulip,hackerkid/zulip,mahim97/zulip,punchagan/zulip,Galexrt/zulip,blaze225/zulip,kou/zulip,verma-varsha/zulip,rishig/zulip,SmartPeople/zulip,vabs22/zulip,hackerkid/zulip,Galexrt/zulip,PhilSk/zulip,dawran6/zulip,rishig/zulip,amanharitsh123/zulip,PhilSk/zulip,christi3k/zulip,Galexrt/zulip,shubhamdhama/zulip,andersk/zulip,susansls/zulip,brockwhittaker/zulip,rht/zulip,vabs22/zulip,susansls/zulip,christi3k/zulip,shubhamdhama/zulip,shubhamdhama/zulip,ryanbackman/zulip,eeshangarg/zulip,mahim97/zulip,jackrzhang/zulip,eeshangarg/zulip,ryanbackman/zulip,rishig/zulip,jainayush975/zulip,samatdav/zulip,amanharitsh123/zulip,amanharitsh123/zulip,jrowan/zulip,andersk/zulip,dawran6/zulip,dattatreya303/zulip,eeshangarg/zulip,jrowan/zulip,SmartPeople/zulip,amanharitsh123/zulip,aakash-cr7/zulip,PhilSk/zulip,blaze225/zulip,punchagan/zulip,PhilSk/zulip,ryanbackman/zulip,j831/zulip,samatdav/zulip,synicalsyntax/zulip,brainwane/zulip,jackrzhang/zulip,zulip/zulip,susansls/zulip,vaidap/zulip,christi3k/zulip,timabbott/zulip,jackrzhang/zulip,jrowan/zulip,jainayush975/zulip,aakash-cr7/zulip,samatdav/zulip,zulip/zulip,kou/zulip,samatdav/zulip