THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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Note: All examples can be found here.
The goals of the Green Team
- Improve green consistency of distributed tests
- Mass test runs determined which tests we worked on
- Prioritized any tests that failed more than once in our mass test runs
- Fixed about 35 issues (working on more)
- Spent about a quarter of our time fixing product bugs
- Anecdotal improvements for Geode developers
- “CIO board is cleaner”
- “Seeing more Green pull requests”
Green Team Progress
"If I had a nickel for every thread sleep related failure..."
What was helpful vs unhelpful
Helpful
| Unhelpful
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"What you can do to make things better?"
Avoid thread sleeping
- Awaitility -- await for some state to change
- CountDownLatch -- coordinate between VMs and/or threads
- Mockito Spy and Verify
- Verify with timeout can be used instead of Awaitility
- Wrap anything with spy or use it to implement a callback such as CacheListener
- Verify is used to validate number of invocations with optional timeout
- All timeouts should use GeodeAwaitility.getTimeout()
- Possible exceptions to the rule
- Busy waiting in loops (Awaitility is usually a better option than custom looping)
- Slow receiver/listener type testing (there’s probably a better way to do it)
Examples: SleepDistributedTest, MultiThreadedIntegrationTest
"It’s not polite to eat all the exceptions..."
Exception handling
- Expected vs unexpected exceptions in tests
- Never catch unexpected exceptions. That is bad... way bad...
- Special case: Asynchronous actions may need to catch checked exceptions and use ErrorCollector
- Use method throws clause for unexpected exceptions
- The alternative serves to make failures more opaque.
- Fixing test failures (as you will have to do at some point) is all about visibility into the problems of the test.
- Use AssertJ catchThrowable or assertThatThrown for expected exceptions
- Avoid using JUnit expected exception support such as ExpectedException Rule or Test annotation expected element. Example: @Test(expected = Exception.class)
- Remember to catch specific exceptions, not whole parent classes. If someone adds an additional exception, will it break your test?
Examples: ErrorHandlingTest, ExpectedExceptionTest
"Sometimes you think they’re helping..."
Minimize helper classes
- All test code should be in the test class
- Test should directly use Geode User APIs without helper classes
- Most Geode developers already know the Geode APIs or should learn them
- See how Geode is configured and what’s happening directly in the test code
- Easier to debug especially if product bugs are suspected
- Developers understand usability issues in the Geode User APIs
- Every layer between the test and what you are testing obscures the test and make debugging more difficult for you and everyone else
- Avoid generalizing classes such as CacheListeners for many tests
- Use specialized inner classes that are specific to the tests in the test class
- Flexibility and generalization are sources of complexity
- Complexity is a source of bugs and difficult debugging
- Complexity and generalization is a wall that prevents people from making educated changes
- All code including configuration should be in the test class
- Write your code for the next person to look at it.
- Helper classes cause problems
- Obscure what’s happening
- Proliferate bad anti-patterns
- Combine test classes that should be separate
"Challenges when handling things asynchronously..."
Use ExecutorServiceRule for multithreading
- Use ExecutorServiceRule or DistributedExcutorServiceRule
- Provides debugging support for hangs
- Cleans up threads on tear down
- Test task code should be interruptible
- Use Future or CompletableFuture for submitted runnable/callable
- Always invoke get() on any Future or CompletableFuture
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- Avoid catching exception and setting some test state to check later
- Use ErrorCollector in unit and integration tests
- Use SharedErrorCollector DistributedErrorCollector in distributed tests
Examples: AsyncErrorHandlingIntegrationTest, AsyncErrorHandlingDistributedTest
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- DistributedRule -- simply launches DUnit and greps for suspect strings after each test method
- DistributedExecutorServiceRule -- provides an ExecutorService for all VMs
- DistributedRestoreSystemProperties -- restores system properties in all VMs
- SharedCountersRule DistributedCounters -- shares counters across all VMs
- SharedErrorCollectorDistributedErrorCollector -- shares one JUnit ErrorCollector across all VMs
Testing tools
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for Cloud
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testing
Mass test run pipeline
- Find and prioritize problematic tests
- Defined under Geode CI
- Matches the CI pipelines
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