Added handler tests and transmissionHandler mock to generate cases

[abhishekj720]

What changed?
Added

• Tests for Register Domain
• Mock for transmission task handler

Why?
As part of code coverage week

How did you test it?
Unit Test

[codecov]

Codecov Report

Merging #5884 (9d04634) into master (edcaf4f) will increase coverage by 0.00%.
The diff coverage is n/a.

Additional details and impacted files

Files	Coverage Δ
common/domain/transmissionTaskHandler.go	93.44% <ø> (ø)

... and 7 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update edcaf4f...9d04634. Read the comment docs.

[coveralls]

Pull Request Test Coverage Report for Build 018eb110-1c58-4b67-88f7-4699eb4b65ae

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 73 unchanged lines in 11 files lost coverage.
• Overall coverage decreased (-0.003%) to 67.258%

---

Files with Coverage Reduction	New Missed Lines	%
common/task/weighted_round_robin_task_scheduler.go	2	88.56%
service/history/execution/mutable_state_util.go	2	78.13%
common/membership/hashring.go	2	82.23%
common/persistence/historyManager.go	2	66.67%
common/task/fifo_task_scheduler.go	3	84.54%
service/history/queue/timer_gate.go	3	95.83%
common/types/shared.go	4	39.91%
service/history/task/transfer_standby_task_executor.go	6	87.01%
service/history/execution/mutable_state_builder.go	7	70.08%
common/testing/history_event_util.go	21	87.95%

Totals
Change from base Build 018eb107-4939-4992-90a4-8071d05eda7e:	-0.003%
Covered Lines:	98183
Relevant Lines:	145979

---

💛 - Coveralls