test corrrectness of readoffset using pipeline tests

@jakebiesinger I used your instruction git cherry-pick to pick only my changes on top of our main branch :). 
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@jakebiesinger @JavierJia @anbangx @Elmira88 please have a look. complete a pipeline test to test whether readHeadOffset still keep correct offset after our P4 random merging. 
And I already add expected results automatic creating function to compare our actual results, now the test is passed.