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https://issues.apache.org/jira/browse/HBASE-4712?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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stack resolved HBASE-4712.
--------------------------
Resolution: Fixed
Fix Version/s: 0.94.0
Hadoop Flags: Reviewed
Committed to trunk. Thanks for the doc. N.
> Document rules for writing tests
> --------------------------------
>
> Key: HBASE-4712
> URL: https://issues.apache.org/jira/browse/HBASE-4712
> Project: HBase
> Issue Type: Task
> Components: test
> Affects Versions: 0.92.0
> Reporter: nkeywal
> Assignee: nkeywal
> Priority: Minor
> Fix For: 0.94.0
>
> Attachments: 4712.txt
>
>
> We saw that some tests could be improved. Documenting the general rules could
> help.
> Proposal:
> HBase tests are divided in three categories: small, medium and large, with
> corresponding JUnit categories: SmallTest, MediumTest, LargeTest
> Small tests are executed in parallel in a shared JVM. They must last less
> than 15 seconds. They must NOT use a cluster.
> Medium tests are executed in separate JVM. They must last less than 50
> seconds. They can use a cluster. They must not fail occasionally.
> Small and medium tests must not need more than 30 minutes to run altogether.
> Small and medium tests should be executed by the developers before submitting
> a patch.
> Large tests are everything else. They are typically integration tests,
> non-regression tests for specific bugs, timeout tests, performance tests.
> Tests rules & hints are:
> - As most as possible, tests should be written as small tests.
> - All tests should be written to support parallel execution on the same
> machine, hence should not use shared resources as fixed ports or fixed file
> names.
> - All tests should be written to be as fast as possible.
> - Tests should not overlog. More than 100 lines/second makes the logs complex
> to read and use i/o that are hence not available for the other tests.
> - Tests can be written with HBaseTestingUtility . This class offers helper
> function to create a temp directory and do the cleanup, or to start a cluster.
> - Sleeps:
> - Tests should not do a 'Thread.sleep' without testing an ending
> condition. This allows understanding what the test is waiting for. Moreover,
> the test will work whatever the machine performances.
> - Sleep should be minimal to be as fast as possible. Waiting for a
> variable should be done in a 40ms sleep loop. Waiting for a socket operation
> should be done in a 200 ms sleep loop.
> - Tests using cluster:
> - Tests using a HRegion do not have to start a cluster: A region can use
> the local file system.
> - Start/stopping a cluster cost around 10 seconds. They should not be
> started per test method but per class.
> - Started cluster must be shutdown using
> HBaseTestingUtility#shutdownMiniCluster, which cleans the directories.
> - As most as possible, tests should use the default settings for the
> cluster. When they don't, they should document it. This will allow to share
> the cluster later.
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