Fix flaky test UtilTest.testEnhanceResponseWithShippingAddressList

[Sujishark]

Description of changes:

This PR aims to fix a test:

com.amazon.pay.api.UtilTest.testEnhanceResponseWithShippingAddressList

This was found by using the NonDex tool.

REASON AND FIX

Encountered the following error while using NonDex:

com.amazon.pay.api.UtilTest.testEnhanceResponseWithShippingAddressList -- Time elapsed: 0.002 s <<< FAILURE!
org.junit.ComparisonFailure: expected:<...pingAddressList":[{"[city":null,"addressId":"amzn1.address.ABC","phoneNumber":"8910111213","postalCode":"123-4567","stateOrRegion":"MNO","county":null,"addressLine3":null,"name":"DEF","district":null,"countryCode":"JP","addressLine2":"JKL","addressLine1":"GHI"]}]}> but was:<...pingAddressList":[{"[postalCode":"123-4567","county":null,"addressId":"amzn1.address.ABC","phoneNumber":"8910111213","countryCode":"JP","addressLine3":null,"addressLine1":"GHI","addressLine2":"JKL","name":"DEF","stateOrRegion":"MNO","city":null,"district":null]}]}>
	at org.junit.Assert.assertEquals(Assert.java:117)
	at org.junit.Assert.assertEquals(Assert.java:146)
	at com.amazon.pay.api.UtilTest.testEnhanceResponseWithShippingAddressList(UtilTest.java:257)

The tests fails when the function testEnhanceResponseWithShippingAddressList() compares both strings (expectedCheckoutSessionResponse.RawResponse and actualCheckoutSessionResponseAfterEnhancing.RawResponse) with key-value pairs in it.

The JSON object is unordered since it uses Maps as their internal data structure. According to documentation,

"This class makes no guarantees as to the order of the map; in particular, it does not guarantee that the order will remain constant over time."

Due to this a non-deterministic order of key-value pairs are maintained and hence the assertEquals fails.

amazon-pay-api-sdk-java/tst/com/amazon/pay/api/UtilTest.java

Line 257 in 3ff564e

Assert.assertEquals(expectedCheckoutSessionResponse.getRawResponse(), actualCheckoutSessionResponseAfterEnhancing.getRawResponse());

One possible solution is to have those strings as JSONObjects and check using JSONObject.similar(), which compares if the contents of two JSON objects are the same, perhaps having a different order of attributes.

amazon-pay-api-sdk-java/tst/com/amazon/pay/api/UtilTest.java

Lines 257 to 259 in ff493ba

	JSONObject expected = new JSONObject(expectedCheckoutSessionResponse.getRawResponse());
	JSONObject actual = new JSONObject(actualCheckoutSessionResponseAfterEnhancing.getRawResponse());
	Assert.assertTrue(expected.similar(actual));

Reproduce:

This was found by using the NonDex tool.

The following command can be used to replicate the failures and validate the fix:

mvn edu.illinois:nondex-maven-plugin:2.1.7-SNAPSHOT:nondex -Dtest=com.amazon.pay.api.UtilTest#testEnhanceResponseWithShippingAddressList

Environment:

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

No user-facing change.
No dependency upgrade.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[zzjas]

You might first want to explain the cause (JSON is unordered) before calling it flaky.

The JSON object is unordered and generally uses Maps as their internal data structure.

I understand the point of introducing HashMap but even if an implementation does not use HashMap, JSON still doesn't guarantee order. So I'm not sure where the focus should be for the root cause. You can think more about it.

Following your discussion on Campuswire, you would also want to include the description of similar and maybe add the link to the doc.