Fix flaky tests in IndexLabelTest due to non deterministic JSON key ordering

[aditya-kumbhar]

Motivation

IndexLabelTest has the following tests that are flaky, detected using the NonDex tool:
org.apache.hugegraph.unit.IndexLabelTest#testIndexLabel
org.apache.hugegraph.unit.IndexLabelTest#testIndexLabelV49
org.apache.hugegraph.unit.IndexLabelTest#testIndexLabelV56

The tests fail due to non-deterministic ordering of the properties in the JSON string created by the JsonUtil.toJson() method.

Command to reproduce

mvn -pl hugegraph-client edu.illinois:nondex-maven-plugin:2.1.1:nondex -Dtest=org.apache.hugegraph.unit.IndexLabelTest

Log

[ERROR]   IndexLabelTest.testIndexLabel:47 expected:<...ame":"personByAge","[id":0,"check_exist":true,"user_data":{},"base_type":"VERTEX_LABEL","base_value":"person","index_type":"SECONDARY","fields":["age"],"rebuild":true]}> but was:<...ame":"personByAge","[check_exist":true,"user_data":{},"id":0,"fields":["age"],"base_value":"person","rebuild":true,"index_type":"SECONDARY","base_type":"VERTEX_LABEL"]}>

[ERROR]   IndexLabelTest.testIndexLabelV49:66 expected:<{"id":0,"[name":"personByAge","check_exist":true],"base_type":"VERTEX...> but was:<{"id":0,"[check_exist":true,"name":"personByAge"],"base_type":"VERTEX...>

[ERROR]   IndexLabelTest.testIndexLabelV56:88 expected:<{"[id":0,"name":"personByAge","check_exist":true,"user_data":{},"base_type":"VERTEX_LABEL","base_value":"person","index_type":"SECONDARY]","fields":["age"]}> but was:<{"[name":"personByAge","id":0,"check_exist":true,"user_data":{},"index_type":"SECONDARY","base_type":"VERTEX_LABEL","base_value":"person]","fields":["age"]}>

Changes

Using the jackson ObjectMapper, comparing the JSONNodes instead of raw json strings would make the test deterministic, as the order of the properties will not be compared.

[imbajin]

thanks，we will take a look for it soon

and what's the influence in production env？

[codecov]

Codecov Report

Merging #398 (2e88ff7) into master (1c47673) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #398   +/-   ##
=========================================
  Coverage     62.55%   62.55%           
  Complexity     1866     1866           
=========================================
  Files           260      260           
  Lines          9405     9405           
  Branches        872      872           
=========================================
  Hits           5883     5883           
  Misses         3140     3140           
  Partials        382      382           

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[aditya-kumbhar]

A flaky test may have no direct impact on production environment, but the tests themselves may fail if moved/run in different java environments due to assumptions made about the determinism of the Java APIs. In this case the order of the elements of the json returned by JsonUtil.toJson() is assumed to be same as the predefined order defined in the expected string json.

The Nondex tool helps in identifying such assumptions by exploring different behaviors of non-deterministic Java APIs and reports the flaky tests.

Fixing the flaky tests would make the behavior of the tests consistent across java environments.

[javeme]

LGTM