The testcase (introduced in
HADOOP-542) is quite obscure because there is no documentation about what it is intending to test. But trying to decipher:
There are two options used in this testcase - mapsideoutput and inputtagged.
Regarding mapsideoutput, what I could guess was it was using a streaming option that caused map outputs to be written to a side effect file and verified that the output from these files was as expected. In the test case, the file was set to be a socket or a local file whose URL was passed to the 'mapsideoutput' option in Streaming.
As Sreekanth pointed out, this option is no longer supported, and hence the test code exercising this option is no longer needed.
inputtagged is still getting added to streaming options in StreamJob. But it doesn't seem to be used anywhere. Can this be confirmed once again, please ? If confirmed to be unused, I am +1 for removing the test case. We must probably remove this option from being used in StreamJob as well, just so it doesn't cause confusion.
If we stick to course to remove the test case, I suggest we remove the target test-unix in Streaming's build.xml. Because with the patch, it is now identical to the test target.