Ignore order of fields in snapshot.

[ftes]

The snapshot is serialized as JSON. JSON does not guarantee ordering of object fields.

RFC7159

An object is an unordered collection of zero or more name/value pairs

However, the snapshot test fails if the order of fields in the serialized JSON has changed.

Snapshot.java#L42

if (!rawSnapshot.trim().equals(currentObject.trim()))

[andrebonna]

JSON is just a way to represent the object being tested with snapshot. If the objects compared are deeply equal, default GSON serializer will serialize them equally every time. If you provide a custom JSON serializer function, you must ensure the same behavior.

[tbo]

default GSON serializer will serialize them equally every time

@andrebonna This doesn't match with my observations. The way some HashMaps are being serialized in my test cases seems to be non-deterministic. I get errors like this one all the time:

Changed content at line 22:
expecting:
  ["        "LFDNR": "1",",
   "        "KTOIBAN": "DE56940596610000008888""]
but was:
  ["        "KTOIBAN": "DE56940596610000008888",",
   "        "LFDNR": "1""]

Is there a way to avoid this behavior?

[andrebonna]

You are right, I totally forgot HashMaps serialization. Fortunatelly, Jackson serializer has a config property to solve this ordering issue, SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS. I just changed the default JSON serializer library from GSON to Jackson and used the config property to ensure always the same key ordering of a map. That should be fixed in version 1.0.14. I'm reopening the issue until you confirm the bug has been solved on your side.

[tbo]

@andrebonna It seems to be fixed. Thanks!

[andrebonna]

I'm generation a new version compiled to Java 8. Version 1.0.15

[metas-ts]

Hi @andrebonna,

it still doesn't work for me, unless I also add

objectMapper.configure(MapperFeature.SORT_PROPERTIES_ALPHABETICALLY, true);

in the method io.github.jsonSnapshot.SnapshotMatcher.buildObjectMapper()

Further reading: https://www.stubbornjava.com/posts/creating-a-somewhat-deterministic-jackson-objectmapper

Pls let me know if I can help with this issue.

[andrebonna]

Please, provide us and example. JSON properties should be in the same order as Class properties definition.

[metas-ts]

Please, provide us an example. JSON properties should be in the same order as Class properties definition.

Thx for the reply. I'm sorry, but I lack the time to look into trying to extract the case into an example. However, as we are open source, if you want you can

• check out our code,

• switch to branch gh4959-app (EDIT: added branch)

• edit https://github.com/metasfresh/metasfresh-webui-api/blob/gh4959-app/pom.xml and remove the -PR from <artifactId>json-snapshot-PR</artifactId>

• and try out the test case https://github.com/metasfresh/metasfresh-webui-api/blob/gh4959-app/src/test/java/de/metas/ui/web/dataentry/window/descriptor/factory/DataEntryTabLoaderTest.java

• Without objectMapper.configure(MapperFeature.SORT_PROPERTIES_ALPHABETICALLY, true); the snapfile sas created on the first run, and then created differently on the second run

• When I run this with #11: Format snapshots using LF only regardless of platform #12 plus objectMapper.configure(MapperFeature.SORT_PROPERTIES_ALPHABETICALLY, true);,
  then it worked in Eclipse (See next copmment for details, i believe it's related but not same same topic)