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From Jesse Yates <jesse.k.ya...@gmail.com>
Subject Re: unit tests
Date Mon, 28 Nov 2011 23:30:51 GMT
Alternatively, a good place for this would also be in the book.xml, under
(13) Building and Developing HBase

-Jesse

On Mon, Nov 28, 2011 at 3:10 PM, Todd Lipcon <todd@cloudera.com> wrote:

> Haven't had a chance to review the full note below, but one request:
> can we please put this in the code tree itself in a file like
> TESTING.txt or README.testing.txt or something?
>
> It'd be nice to be able to refer back to it from within the code tree.
>
> -Todd
>
> On Mon, Nov 28, 2011 at 12:29 PM, N Keywal <nkeywal@gmail.com> wrote:
> > Hi,
> >
> > The surefire modification seems to work well, so we can move to the final
> > step.
> > Please find below the last proposition for the test. The behavior
> described
> > can be activated with:
> >  - a commit of hbase-4847
> >  - a modification of the jenkins config to run mvn verify vs. mvn tests.
> >
> > The main points are:
> >  - should we run small & medium tests only by default on a developer
> > machine => here answer is yes
> >  - should we run all tests on the central build => here answer is yes
> >  - should we stop when a small test fails => here answer is yes
> >  - should we stop when a medium test fails => here answer is yes
> >
> >
> > Also, I just had a discussion with Jesse, who think we should keep/have
> the
> > notion of integration test. If retained, the points above must be
> impacted
> > to take this into account.
> >
> >
> > fyi, there are today:
> >  - 416 small tests, executed in ~3 minutes
> >  - 489 medium tests, executed in ~35 minutes (without parallelization)
> >  - 280 large tests, executed in ~90 minutes (without parallelization)
> >
> > --
> > 1) Running tests
> > HBase tests are divided in three categories: small, medium and large,
> with
> > corresponding JUnit categories: SmallTests, MediumTests, LargeTests.
> >
> > - Small tests are executed in a shared JVM. We put in this category all
> the
> > tests that can be executed quickly (the maximum execution time for a test
> > is 15 seconds, and they do not use a cluster) in a shared jvm.
> > - Medium tests represents tests that must be executed before proposing a
> > patch. They are designed to run in less than 30 minutes altogether, and
> are
> > quite stable in their results. They're designed to last less than 50
> > seconds individually. They can use a cluster, and each of them is
> executed
> > in a separate JVM.
> > - Large tests are everything else. They are typically integration tests,
> > regression tests for specific bugs, timeout tests, performance tests.
> Some
> > of them can be flaky. They are executed before a commit on the
> > pre-integration machines. They can be run on the developer machine as
> well.
> >
> > Commands are:
> > 1) mvn test
> >  - execute small tests in a single JVM and medium tests in a separate JVM
> > for each test
> >  - medium tests are NOT executed if there is an error in a small test
> >  - large tests are NOT executed
> >  - there is one report for small tests, and one report for medium tests
> -if
> > they are executed-
> >
> > 2) mvn verify
> >  - execute small tests in a single JVM then medium tests in a separate
> JVM
> > for each test, then large tests in a separate JVM as well.
> >  - medium tests are NOT executed if there is an error in a small test
> >  - large tests are NOT executed if there is an error in a small or medium
> > test
> >  - there is one report by test category, small, medium and large
> >
> > 3) mvn test -P localTests -Dtest=myTests
> >  - remove any category effect (without this specific profile, the
> profiles
> > are taken into account)
> >  - use actually the official release of surefire & the old connector to
> > junit
> >  - tests are executed in separated JVM
> > - You will see a new message at the end of the report: "[INFO] Tests are
> > skipped". It's harmless.
> >
> > 4) mvn test -P runAllTests
> >  - execute small tests in a single JVM then medium & large tests in a
> > separate JVM for each test
> >  - medium and large tests are NOT executed if there is an error in a
> small
> > test
> >  - large tests are NOT executed if there is an error in a small or medium
> > test
> >  - there are one report for small tests, and one report for medium &
> large
> > tests -if they are executed-
> >
> > 5) Various other profiles
> >  - mvn test -P runSmallTests   - execute small tests only,  in a single
> JVM.
> >  - mvn test -P runMediumTests   - execute medium tests in a single JVM.
> >  - mvn test -P runLargeTests   - execute medium tests in a single JVM.
> >
> > It's as well possible to use the script 'hbasetests.sh'. This script runs
> > the medium and large tests in parallel with two maven instances, and
> > provide a single report. It must be executed from the directory which
> > contains the pom.xml. Commands are:
> > ./dev-support/hbasetests.sh              - execute small and medium tests
> > ./dev-support/hbasetests.sh runAllTests  - execute all tests
> > ./dev-support/hbasetests.sh replayFailed - rerun the failed tests a
> second
> > time, in a separate jvm and without parallelisation.
> >
> > 2) Writing tests
> > Tests rules & hints are:
> > - As most as possible, tests should be written as small tests.
> > - All tests must be written to support parallel execution on the same
> > machine, hence should not use shared resources as fixed ports or fixed
> file
> > names.
> > - 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
> > functions to create a temp directory and do the cleanup, or to start a
> > cluster.
> >
> > - Categories and execution time
> >  - All tests must be categorized, if not they could be skipped.
> >  - All tests should be written to be as fast as possible.
> >  - Small tests should last less than 15 seconds, and must not have any
> > side effect.
> >  - Medium tests should last less than 45 seconds.
> >  - large tests should last less than 3 minutes, this ensure a good
> > parallelization for the ones using it, and ease the analysis when the
> test
> > fails.
> >
> > - Sleeps:
> >    - Whenever possible, tests should not use sleep, but rather waiting
> for
> > the real event. This is faster and clearer for the reader.
> >    - 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  a 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 test 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.
> >
>
>
>
> --
> Todd Lipcon
> Software Engineer, Cloudera
>



-- 
-------------------
Jesse Yates
240-888-2200
@jesse_yates

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