feat: unit tests and STM annotations for chain module.

[zl03jsj]

关联的Issues (Related Issues)

closes #5421

改动 (Proposed Changes)

feat: unit tests and STM annotations for chain module.

附注 (Additional Info)

自查清单 (Checklist)

在你认为本 PR 满足被审阅的标准之前，需要确保 / Before you mark the PR ready for review, please make sure that:

• 符合Venus项目管理规范中关于PR的相关标准 / The PR follows the PR standards set out in the Venus project management guidelines
• 具有清晰明确的commit message / All commits have a clear commit message.
• 包含相关的的测试用例或者不需要新增测试用例 / This PR has tests for new functionality or change in behaviour or not need to add new tests.
• 包含相关的的指南以及文档或者不需要新增文档 / This PR has updated usage guidelines and documentation or not need
• 通过必要的检查项 / All checks are green

[codecov-commenter]

Codecov Report

Merging #5434 (5957f73) into master (d2d388e) will increase coverage by 1%.
The diff coverage is 100%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #5434    +/-   ##
=======================================
+ Coverage      24%     26%    +1%     
=======================================
  Files         605     605            
  Lines       67861   67864     +3     
=======================================
+ Hits        16924   17693   +769     
+ Misses      48750   47913   -837     
- Partials     2187    2258    +71     

[simlecode]

+LGTM

[LinZexiao]

LGTM