[Bug] Nondeterministic ordering in MongoSourceTest.testWriteBadMessage

[LucasEby]

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• I understand that unsupported versions don't get bug fixes. I will attempt to reproduce the issue on a supported version of Pulsar client and Pulsar broker.

User environment

Broker version: 4.2.0-SNAPSHOT
Broker Operating system and hardware type: Linux x86_64 GNU/Linux
Broker Java version: 17.0.16

Issue Description

The test was written with the incorrect assumption that the compared strings have a deterministic order. Since the original data was stored with HashMaps, which makes no guarantees to the order of it's map, the resulting strings that were compared could potentially have reordered contents. The ordering can change due to different environments producing the contents in different orders despite the logical contents being the same. Since the raw strings/trees were compared "as-is", harmless re-ordering could flip the test from pass to fail despite the data being semantically the same.

I discovered the problem with the NonDex tool. NonDex systematically detects incorrect tests that rely on non-deterministic behaviors in Java APIs—like assuming order of the contents of HashMaps — by exploring all specification-allowed outcomes. It does this by instrumenting undetermined APIs and randomizing the returned order/behavior within what the spec allows. Failures it exposes reliably indicate flawed assumptions in order that were never promised and should be fixed.

Error messages

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running org.apache.pulsar.io.mongodb.MongoSourceTest
[ERROR] Tests run: 2, Failures: 1, Errors: 0, Skipped: 1, Time elapsed: 3.958 s <<< FAILURE! -- in org.apache.pulsar.io.mongodb.MongoSourceTest
[ERROR] org.apache.pulsar.io.mongodb.MongoSourceTest.testWriteBadMessage -- Time elapsed: 0.017 s <<< FAILURE!
java.lang.AssertionError: expected [{"fullDocument":{"hello":"pulsar"},"ns":{"databaseName":"hello","collectionName":"pulsar","fullName":"hello.pulsar"},"operation":"INSERT"}] but found [{"fullDocument":{"hello":"pulsar"},"operation":"INSERT","ns":{"fullName":"hello.pulsar","collectionName":"pulsar","databaseName":"hello"}}]
        at org.testng.Assert.fail(Assert.java:110)
        at org.testng.Assert.failNotEquals(Assert.java:1577)
        at org.testng.Assert.assertEqualsImpl(Assert.java:149)
        at org.testng.Assert.assertEquals(Assert.java:131)
        at org.testng.Assert.assertEquals(Assert.java:655)
        at org.testng.Assert.assertEquals(Assert.java:665)
        at org.apache.pulsar.io.mongodb.MongoSourceTest.testWriteBadMessage(MongoSourceTest.java:131)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:569)
        at org.testng.internal.invokers.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:139)
        at org.testng.internal.invokers.InvokeMethodRunnable.runOne(InvokeMethodRunnable.java:47)
        at org.testng.internal.invokers.InvokeMethodRunnable.call(InvokeMethodRunnable.java:76)
        at org.testng.internal.invokers.InvokeMethodRunnable.call(InvokeMethodRunnable.java:11)
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
        at java.base/java.lang.Thread.run(Thread.java:840)

[INFO] 
[INFO] Results:
[INFO] 
[ERROR] Failures: 
[ERROR] org.apache.pulsar.io.mongodb.MongoSourceTest.testWriteBadMessage
[INFO]   Run 1: PASS
[ERROR]   Run 2: MongoSourceTest.testWriteBadMessage:131 expected [{"fullDocument":{"hello":"pulsar"},"ns":{"databaseName":"hello","collectionName":"pulsar","fullName":"hello.pulsar"},"operation":"INSERT"}] but found [{"fullDocument":{"hello":"pulsar"},"operation":"INSERT","ns":{"fullName":"hello.pulsar","collectionName":"pulsar","databaseName":"hello"}}]     
[INFO] 
[INFO] 
[ERROR] Tests run: 1, Failures: 1, Errors: 0, Skipped: 0

Reproducing the issue

You can replicate the problem with the NonDex tool command:
mvn -pl pulsar-io/mongo -Dtest=org.apache.pulsar.io.mongodb.MongoSourceTest#testWriteBadMessage -DforkCount=1 -DnondexRuns=1 -DnondexSeed=1016066 -DreuseForks=false edu.illinois:nondex-maven-plugin:2.2.1:nondex

Additional information

No response

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• I'm willing to submit a PR!