Comparing 2 objects in JUnit

Question

I am trying to learn JUnit and I have been practicing it for some time now I have a problem in comparing 2 objects. That is think of it as JSON objects. I am using GSON for this purpose

For example, I have a JSON string and I have converted it into an object and I have another JSON object which will be exactly the same, now when I write assertEquals for these 2 objects it's returning something like

java.lang.AssertionError:   
  Expected :Data@2ret9593
  Actual   :Data@7647qe21

As they are JSON objects the order of the key-value pairs may differ but I want it to check them and return the result if they are equal or not and ignore some fields whose values are not considered but the field is important like timestamp or dynamically generated id etc.

It's not just about equal method What I was trying here I to compare 2 JSON strings and ignore some fields that are dynamically allocated while testing

For example:

{"name": "ray", "age": "20"} == {"age": "20", "name": "ray", "timestamp": 03:10:54}

Is there any way to achieve what I want?

you are actually comparing references to objects, not their values. iterate over the contents and check if the other one contains it as well — Stultuske, Jan 16 '18 at 10:30
So basically I need to write my own equal method for all the fields in the Json — Srikar, Jan 16 '18 at 10:36
Or you could assert using the JSON without deserilaising into an object at all (see the answer below suggesting the use of JSONAssert). — glytching, Jan 16 '18 at 10:38

score 3 · Accepted Answer · answered Jan 16 '18 at 10:35

Rather than deserialising JSON into an object to facilitate comparison you could use JSONAssert to facilitate meaningful 'JSON comparison' in your test cases.

For example:

String expected = "{"name": "ray", "age": "20"}";
String actual = "{"age": "20", "name": "ray"}"
JSONAssert.assertEquals(expected, actual, false);

In this example strict has been set to false, this instructs JSONAssert to forgive reordering.

To use JSONAssert just download the JAR or - if using Maven - add the following to your project's pom.xml:

<dependency>
    <groupId>org.skyscreamer</groupId>
    <artifactId>jsonassert</artifactId>
    <version>1.5.0</version>
    <scope>test</scope>
</dependency>

And add assertions like this:

JSONAssert.assertEquals(expectedJSONString, actualJSON, strictMode);

More examples in the cookbook.

hey, glytching is there any way to ignore some fields if some conditions are met and check those fields if the condition fails. — Srikar, Jan 22 '18 at 09:30
You could perhaps provide your own implementation of jsonasserts' `DefaultComparator`. FWIW, there's a lengthy discussion of partial assertions on [this JSONAssert issue](https://github.com/skyscreamer/JSONassert/issues/15). — glytching, Jan 22 '18 at 09:45

Comparing 2 objects in JUnit

1 Answers1