[BUG] Test case org.opensearch.action.admin.cluster.shards.CatShardsRequestTests.testSerializationWithOlderVersionsParametersNotSerialized fails with NPE

[reta]

Describe the bug

The test case org.opensearch.action.admin.cluster.shards.CatShardsRequestTests.testSerializationWithOlderVersionsParametersNotSerialized fails with NPE:

java.lang.NullPointerException: Cannot invoke "String.length()" because "str" is null
	at __randomizedtesting.SeedInfo.seed([644E83AFC71A1C4F:8FD495376ADAAC0E]:0)
	at org.opensearch.core.common.io.stream.StreamOutput.writeString(StreamOutput.java:444)
	at org.opensearch.core.common.io.stream.StreamOutput.writeStringArray(StreamOutput.java:547)
	at org.opensearch.action.admin.cluster.shards.CatShardsRequest.writeTo(CatShardsRequest.java:57)
	at org.opensearch.action.admin.cluster.shards.CatShardsRequestTests.testSerializationWithOlderVersionsParametersNotSerialized(CatShardsRequestTests.java:101)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1750)
	at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:938)
	at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:974)
	at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:988)
	at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	at org.apache.lucene.tests.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:48)
	at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
	at org.apache.lucene.tests.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:45)
	at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
	at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
	at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:368)
	at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:817)
	at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:468)
	at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:947)
	at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:832)
	at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:883)
	at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:894)
	at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
	at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
	at org.apache.lucene.tests.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:38)
	at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
	at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
	at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
	at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
	at org.apache.lucene.tests.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
	at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
	at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
	at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
	at org.apache.lucene.tests.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:47)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
	at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:368)
	at java.base/java.lang.Thread.run(Thread.java:1583)

Related component

Other

To Reproduce

Pull https://github.com/opensearch-project/OpenSearch/pull/16571 and run ./gradlew ':server:test' --tests "org.opensearch.action.admin.cluster.shards.CatShardsRequestTests.testSerializationWithOlderVersionsParametersNotSerialized"

Expected behavior

The test case should pass

Additional Details

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• CI

Additional context
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[reta]

@gargharsh3134 could you please take a look? caused by #14641 / #16455

[reta]

Blocks #16571

[dbwiddis]

The test creates a string array:

OpenSearch/server/src/test/java/org/opensearch/action/admin/cluster/shards/CatShardsRequestTests.java

Line 96 in 99a9a81

catShardsRequest.setIndices(new String[2]);

But the elements of the array are null, and thus fail when attempting to serialize for transport.

The failure didn't occur on 3.0.0 or 2.8.0 because the previous version didn't pass the "on or after" check and never attempted to serialize the array of nulls. It's failing on 2.8.1 because the previous version is 2.8.0 and does meet the earlier version on or after 2.8.0, and reads the string array.

Fix is probably populating that string array with some random strings, similar to how is done in another test in the same class:

OpenSearch/server/src/test/java/org/opensearch/action/admin/cluster/shards/CatShardsRequestTests.java

Lines 42 to 45 in 99a9a81

	String[] indices = new String[numIndices];
	for (int i = 0; i < numIndices; i++) {
	indices[i] = randomAlphaOfLengthBetween(3, 10);
	}

[dblock]

@dbwiddis Did #16590 fix this? Backported? Close?

[Catch All Triage - 1, 2, 3, 4, 5]

[dbwiddis]

Yes, this was fixed by #16590 and #16591