Fixed non-idempotent unit tests in `AsyncHBaseTest` and `HBaseClient1Test`

[kaiyaok2]

Motivation:

Tests in the AsyncHBaseTest and HBaseClient1Test are not idempotent and fail in repeated runs, because they pollute a state reused by themselves. Take AsyncHBaseTest as an example - the tests used the shared AsyncHBaseClient instance client to perform operations including read() and insert(). However, client is not cleaned up after the tests, so the repeated runs fail. Fixing non-idempotent tests can help proactively avoid state pollution that results in test order dependency (which could then hurt regression testing under test selection / prioritization / parallelization).

The list of non-idempotent tests are:

• AsyncHBaseTest#testScan
• AsyncHBaseTest#testRead
• AsyncHBaseTest#testReadMissingRow
• AsyncHBaseTest#testUpdate
• HBaseClient1Test#testScan
• HBaseClient1Test#testRead
• HBaseClient1Test#testReadMissingRow
• HBaseClient1Test#testUpdate
• HBaseClient2Test#testScan
• HBaseClient2Test#testRead
• HBaseClient2Test#testReadMissingRow
• HBaseClient2Test#testUpdate

Reproduce

Reproduce:

Using the NIOInspector plugin that supports rerunning JUnit tests in the same environment. Use HBaseClient1Test as an example:

cd hbase1
mvn edu.illinois:NIOInspector:rerun -Dtest=site.ycsb.db.hbase1.HBaseClient1Test

Error messages for the failed tests in the second run:

• testScan():

  java.lang.AssertionError: expected:<5> but was:<0>

• testReadMissingRow():

  java.lang.AssertionError: expected:<Status [name=NOT_FOUND, description=The requested record was not found.]> but was:<Status [name=ERROR, description=The operation failed.]>

• testRead():

  java.lang.AssertionError: expected:<Status [name=OK, description=The operation completed successfully.]> but was:<Status [name=ERROR, description=The operation failed.]>

• testUpdate():

  java.lang.AssertionError: expected:<Status [name=OK, description=The operation completed successfully.]> but was:<Status [name=ERROR, description=The operation failed.]>

  Proposed Fix

  Clean up client in the tear down function.

[kaiyaok2]

@busbey @joshelser Please review