node tests: Add huddle_string test.
node tests: Add huddle_string test.

zulip/zulip,eeshangarg/zulip,andersk/zulip,hackerkid/zulip,zulip/zulip,rht/zulip,zulip/zulip,rht/zulip,zulip/zulip,punchagan/zulip,rht/zulip,kou/zulip,kou/zulip,punchagan/zulip,hackerkid/zulip,kou/zulip,andersk/zulip,hackerkid/zulip,rht/zulip,hackerkid/zulip,kou/zulip,andersk/zulip,kou/zulip,andersk/zulip,rht/zulip,rht/zulip,punchagan/zulip,zulip/zulip,andersk/zulip,eeshangarg/zulip,eeshangarg/zulip,kou/zulip,zulip/zulip,punchagan/zulip,andersk/zulip,kou/zulip,punchagan/zulip,punchagan/zulip,hackerkid/zulip,hackerkid/zulip,zulip/zulip,eeshangarg/zulip,eeshangarg/zulip,eeshangarg/zulip,andersk/zulip,hackerkid/zulip,rht/zulip,punchagan/zulip,eeshangarg/zulip