test: Add unit test for seata-tm module

[wangwei-ying]

Ⅰ. Describe what this PR did

test: Add unit test to seata-tm module

Ⅱ. Does this pull request fix one issue?

#194

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov-io]

Codecov Report

Merging #1817 into develop will increase coverage by 0.36%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             develop    #1817      +/-   ##
=============================================
+ Coverage         55%   55.37%   +0.36%     
- Complexity      2361     2378      +17     
=============================================
  Files            422      422              
  Lines          14314    14314              
  Branches        1716     1716              
=============================================
+ Hits            7874     7926      +52     
+ Misses          5709     5654      -55     
- Partials         731      734       +3

Impacted Files	Coverage Δ	Complexity Δ
...server/store/file/FileTransactionStoreManager.java	59.21% <0%> (-0.99%)	29% <0%> (ø)
...va/io/seata/tm/api/transaction/NoRollbackRule.java	100% <0%> (+12.5%)	6% <0%> (+1%)	⬆️
...ata/tm/api/transaction/TransactionHookManager.java	80% <0%> (+13.33%)	6% <0%> (+1%)	⬆️
...ain/java/io/seata/tm/TransactionManagerHolder.java	84.61% <0%> (+15.38%)	4% <0%> (+1%)	⬆️
...java/io/seata/tm/api/transaction/RollbackRule.java	100% <0%> (+17.85%)	15% <0%> (+3%)	⬆️
...java/io/seata/tm/api/DefaultGlobalTransaction.java	70.96% <0%> (+19.35%)	19% <0%> (+4%)	⬆️
...java/io/seata/tm/api/GlobalTransactionContext.java	100% <0%> (+23.07%)	6% <0%> (+1%)	⬆️
...ava/io/seata/tm/api/DefaultFailureHandlerImpl.java	72.72% <0%> (+72.72%)	6% <0%> (+6%)	⬆️

[zjinlei]

Thanks

[xingfudeshi]

Thanks.I left some comments.

[xingfudeshi]

LGTM.

[slievrly]

LGTM

[slievrly]

@wangwei-ying thank you very much.