tests: Add coverage for message truncation logic.
tests: Add coverage for message truncation logic.

hackerkid/zulip,zulip/zulip,dhcrzf/zulip,jackrzhang/zulip,dhcrzf/zulip,showell/zulip,andersk/zulip,showell/zulip,punchagan/zulip,brainwane/zulip,punchagan/zulip,jackrzhang/zulip,timabbott/zulip,tommyip/zulip,dhcrzf/zulip,showell/zulip,hackerkid/zulip,brainwane/zulip,eeshangarg/zulip,hackerkid/zulip,showell/zulip,zulip/zulip,kou/zulip,dhcrzf/zulip,hackerkid/zulip,rht/zulip,shubhamdhama/zulip,zulip/zulip,tommyip/zulip,dhcrzf/zulip,eeshangarg/zulip,andersk/zulip,shubhamdhama/zulip,rht/zulip,rht/zulip,tommyip/zulip,punchagan/zulip,brainwane/zulip,shubhamdhama/zulip,jackrzhang/zulip,zulip/zulip,andersk/zulip,timabbott/zulip,timabbott/zulip,timabbott/zulip,synicalsyntax/zulip,eeshangarg/zulip,showell/zulip,synicalsyntax/zulip,hackerkid/zulip,rishig/zulip,rishig/zulip,punchagan/zulip,andersk/zulip,rht/zulip,eeshangarg/zulip,jackrzhang/zulip,synicalsyntax/zulip,tommyip/zulip,brainwane/zulip,zulip/zulip,punchagan/zulip,kou/zulip,tommyip/zulip,shubhamdhama/zulip,synicalsyntax/zulip,rht/zulip,punchagan/zulip,showell/zulip,kou/zulip,rishig/zulip,rht/zulip,hackerkid/zulip,synicalsyntax/zulip,rishig/zulip,brainwane/zulip,timabbott/zulip,hackerkid/zulip,synicalsyntax/zulip,brainwane/zulip,zulip/zulip,shubhamdhama/zulip,kou/zulip,rishig/zulip,jackrzhang/zulip,kou/zulip,andersk/zulip,punchagan/zulip,andersk/zulip,eeshangarg/zulip,eeshangarg/zulip,andersk/zulip,synicalsyntax/zulip,jackrzhang/zulip,zulip/zulip,rht/zulip,showell/zulip,shubhamdhama/zulip,eeshangarg/zulip,rishig/zulip,jackrzhang/zulip,kou/zulip,timabbott/zulip,brainwane/zulip,tommyip/zulip,shubhamdhama/zulip,kou/zulip,timabbott/zulip,tommyip/zulip,dhcrzf/zulip,rishig/zulip,dhcrzf/zulip