test(streaming): add unit tests for chain v2

[BugenZhao]

Signed-off-by: Bugen Zhao [email protected]

What's changed and what's your intention?

As title. This PR also adds a flag for "sending a stop barrier on stream finish" for MockSource.

Checklist

• I have written necessary docs and comments
• I have added necessary unit tests and integration tests

Refer to a related PR or issue link (optional)

• feat(streaming): introduce async-stream based ChainExecutorV2 #1469

[codecov]

Codecov Report

Merging #1491 (8247e44) into main (1d13c51) will increase coverage by 0.05%.
The diff coverage is 94.59%.

@@             Coverage Diff              @@
##               main    #1491      +/-   ##
============================================
+ Coverage     70.46%   70.51%   +0.05%     
  Complexity     2766     2766              
============================================
  Files          1029     1029              
  Lines         90259    90333      +74     
  Branches       1790     1790              
============================================
+ Hits          63598    63701     +103     
+ Misses        25770    25741      -29     
  Partials        891      891              

Flag	Coverage Δ
java	61.01% <ø> (ø)
rust	72.54% <94.59%> (+0.06%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
rust/stream/src/executor_v2/test_utils.rs	59.32% <88.88%> (+19.32%)	⬆️
rust/stream/src/executor_v2/chain.rs	75.45% <95.38%> (+75.45%)	⬆️
rust/connector/src/filesystem/file_common.rs	81.16% <0.00%> (+0.44%)	⬆️
rust/stream/src/executor/mod.rs	61.22% <0.00%> (+1.63%)	⬆️

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