Add tests for mutable_state_builder_methods_child_workflow

[natemort]

What changed?

• Increased test coverage from 1% to 89%

Why?

• Increasing test coverage

How did you test it?

• Unit tests

Potential risks

• None, this change is test only.

Release notes

Documentation Changes

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 68.84%. Comparing base (4cc5736) to head (b5eac1f). Report is 4 commits behind head on master.

Additional details and impacted files

[see 12 files with indirect coverage changes](https://app.codecov.io/gh/uber/cadence/pull/6088/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=uber) ------ [Continue to review full report in Codecov by Sentry](https://app.codecov.io/gh/uber/cadence/pull/6088?dropdown=coverage&src=pr&el=continue&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=uber). > **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=uber) > `Δ = absolute (impact)`, `ø = not affected`, `? = missing data` > Powered by [Codecov](https://app.codecov.io/gh/uber/cadence/pull/6088?dropdown=coverage&src=pr&el=footer&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=uber). Last update [af66f14...b5eac1f](https://app.codecov.io/gh/uber/cadence/pull/6088?dropdown=coverage&src=pr&el=lastupdated&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=uber). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=uber).

[coveralls]

Pull Request Test Coverage Report for Build 018fe04c-c35c-464d-a850-d522171861a2

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 35 unchanged lines in 7 files lost coverage.
• Overall coverage increased (+0.2%) to 69.897%

---

Files with Coverage Reduction	New Missed Lines	%
service/history/execution/mutable_state_util.go	2	78.52%
service/matching/tasklist/matcher.go	2	88.66%
common/types/history.go	4	45.35%
service/history/task/transfer_standby_task_executor.go	5	87.55%
service/history/task/fetcher.go	5	85.57%
service/history/task/cross_cluster_task_processor.go	8	80.79%
service/history/engine/engineimpl/record_activity_task_started.go	9	68.87%
<!--	Total:	35		-->

Totals
Change from base Build 018fe042-ab11-41df-a347-75d7690ef633:	0.2%
Covered Lines:	103403
Relevant Lines:	147936

---

💛 - Coveralls