Fix flaky test in JSONUtilTest

[bbelide2]

Use JSONAssert instead of Assert in JSONUtilTest to fix a flaky test

Flaky test case: cn.hippo4j.common.toolkit.JSONUtilTest.cn.hippo4j.common.toolkit.JSONUtilTest.assertToJSONString

hippo4j/infra/common/src/test/java/cn/hippo4j/common/toolkit/JSONUtilTest.java

Line 43 in 472d345

public void assertToJSONString() {

Problem

Test assertToJSONString in JSONUtilTest is detected as flaky with the NonDex tool. The test failed with the following error:

Failed tests: assertToJSONString(cn.hippo4j.common.toolkit.JSONUtilTest): expected:<{"[id":1,"name":"foo1","foo":{"id":2,"name":"foo2"}]}> but was:<{"[foo":{"id":2,"name":"foo2"},"id":1,"name":"foo1"]}>

Root cause

In this test, two JSON strings are compared using Assert.assertEquals() in this part of the code:

hippo4j/infra/common/src/test/java/cn/hippo4j/common/toolkit/JSONUtilTest.java

Line 45 in 472d345

Assert.assertEquals(EXPECTED_FOO_JSON, JSONUtil.toJSONString(EXPECTED_FOO));

Using Assert.assertEquals() will lead to flaky tests due to mismatch in the order of properties or if there are nested structures. In this particular test case, JSON object(Foo) contains a nested object of the same type leading to difference in the order of properties thus making it a flaky test.

In this test, a hardcoded JSON string "EXPECTED_FOO_JSON" is compared with another JSON string created by JSONUtil.toJSONString(). The input to this method is an object of class Foo (test class present in JSONUtilTest).

Fix

Changed Assert.assertEquals() to JSONAssert.assertEquals() which is order insensitive.

How this has been tested?

Java: openjdk version "11.0.20.1"
Maven: Apache Maven 3.6.3

1. Module build - Successful
   Command used -

mvn install -pl infra/common -am -DskipTests

2. Regular test - Successful
   Command used -

mvn -pl infra/common test -Dtest=cn.hippo4j.common.toolkit.JSONUtilTest#assertToJSONString

3. NonDex test - Failed
   Command used -

mvn -pl infra/common edu.illinois:nondex-maven-plugin:2.1.1:nondex -Dtest=cn.hippo4j.common.toolkit.JSONUtilTest#assertToJSONString

NonDex test passed after the fix.

Alternate fix

Add @JsonPropertyOrder({"id", "name", "foo"}) annotation to Foo class so that the order of properties whenever an object of this class is converted to JSON string remains same. Since the order now always remains same, the JSON string always matches with our expected string thus fixing the flaky test. This change will not impact code since Foo class is only used in tests.

[codecov]

Codecov Report

Attention: 36 lines in your changes are missing coverage. Please review.

Comparison is base (e98b106) 34.45% compared to head (148be1c) 34.33%.
Report is 16 commits behind head on develop.

❗ Current head 148be1c differs from pull request most recent head 2c91797. Consider uploading reports for the commit 2c91797 to get more accurate results

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #1495      +/-   ##
=============================================
- Coverage      34.45%   34.33%   -0.13%     
- Complexity       846      847       +1     
=============================================
  Files            262      262              
  Lines           5918     5936      +18     
  Branches         554      554              
=============================================
- Hits            2039     2038       -1     
- Misses          3686     3705      +19     
  Partials         193      193              

Files	Coverage Δ
...essage/core/platform/WeChatSendMessageHandler.java	0.00% <0.00%> (ø)
...config/service/biz/impl/HisRunDataServiceImpl.java	0.00% <0.00%> (ø)

... and 1 file with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.