huiyang chi created CURATOR-694:
-----------------------------------

             Summary: Improve test reliability by resolving nondeterministic 
order by sorting
                 Key: CURATOR-694
                 URL: https://issues.apache.org/jira/browse/CURATOR-694
             Project: Apache Curator
          Issue Type: Improvement
          Components: Framework
    Affects Versions: 5.5.0
         Environment: # Reproduce
This error can be reproduced with the 
[NondexTool](https://github.com/TestingResearchIllinois/NonDex) with the 
following command (you can try that without modifying the pom, but feel free to 
use the plugin to protect your project and make it safer 😊 ), and this kind 
problem is widely documented in [International Dataset of Flaky Tests 
(IDoFT)](https://github.com/TestingResearchIllinois/idoft)

```
mvn edu.illinois:nondex-maven-plugin:2.1.7-SNAPSHOT:nondex -pl 
/curator-framework -Dsurefire.useFile=false 
-Dtest=org.apache.curator.framework.imps.TestReconfiguration#[methodName]
```


Let's make the curator more reliable together 👩🏻‍🔧
            Reporter: huiyang chi
             Fix For: awaiting-response


The related PR has been opened : [https://github.com/apache/curator/pull/491]

 

# Problem

For these tests:

[INFO] org.apache.curator.framework.imps.TestReconfiguration#testAdd
[INFO] 
org.apache.curator.framework.imps.TestReconfiguration#testNewMembersWithEmptyList
[INFO] org.apache.curator.framework.imps.TestReconfiguration#testAddAsync
[INFO] org.apache.curator.framework.imps.TestReconfiguration#testAddAndRemove
[INFO] 
org.apache.curator.framework.imps.TestReconfiguration#testAddAndRemoveWithEmptyList
[INFO] org.apache.curator.framework.imps.TestReconfiguration#testBasicGetConfig
[INFO] 
org.apache.curator.framework.imps.TestReconfiguration#testRemoveWithChroot

They assume the order of the QuorumServer was same, but this is not necessary 
the case because QuorumMaj aggressively use Map to store it's data

```
    private Map<Long, QuorumPeer.QuorumServer> allMembers = new HashMap();
    private HashMap<Long, QuorumPeer.QuorumServer> votingMembers = new 
HashMap();
    private HashMap<Long, QuorumPeer.QuorumServer> observingMembers = new 
HashMap();
```
so because the order of the Map is indeterministic according to the [Oracle's 
official 
document](https://docs.oracle.com/javase/8/docs/api/java/util/HashMap.html#:~:text=This%20class%20makes%20no%20guarantees%20as%20to%20the%20order%20of%20the%20map),
 so this might trigger error message in different environments:

```
[ERROR] org.apache.curator.framework.imps.TestReconfiguration.testAdd  Time 
elapsed: 0.641 s  <<< FAILURE!
org.opentest4j.AssertionFailedError: expected: 
<127.0.0.1:55254,127.0.0.1:55251,127.0.0.1:55248,0.0.0.0:55268> but was: 
<0.0.0.0:55268,127.0.0.1:55251,127.0.0.1:55248,127.0.0.1:55254>
        at 
org.apache.curator.framework.imps.TestReconfiguration.testAdd(TestReconfiguration.java:281)

```
# Solution

So the most precise way to deal with that would be change the 
configToConnectionString method to make sure when we serialize the 
configurations, we always get the same result, so that the tests will be safe 
in different environment (because the order of the map is undefined)



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