Is there any library that helps with json introspe...

# kotest

[Jonathan Olsson]

Is there any library that helps with json introspection? Coming from spock+groovy, using kotest+serializationx is a bit ... crude for e2e testing of web services.

[Emil Kantis]

What do you want to do? There’s json assertions if that’s what you need

[Jonathan Olsson]

obj = {
    "id": "someId",
    "someList": [
        {
            "a": "foo"
        }
    ]
}

I want to be able to do something along the lines of:

obj.id shouldBe "someId"
obj.someList[0].a shouldBe "foo"

[Jonathan Olsson]

Without having to define all the necessary data classes.

[Jonathan Olsson]

I guess it would be possible to achieve:

obj["id"] shouldBe "someId"
obj["someList"][0]["a"] shouldBe "foo"

[Jonathan Olsson]

Not as "fancy" as groovy for this purpose, but would be good enough for my purposes.

[Emil Kantis]

obj shouldEqualJson {
  fieldComparison = FieldComparison.Lenient // Ignore properties not defined in `expected`
  """
  {
    "id": "someId",
    "someList": [{ "a": "foo" }]
  }
  """
}

[Jonathan Olsson]

Interesting. Yes, this will help a lot. Won't however help with another convenient thing with the dynamic approach of groovy, field extraction. For instance:

id = obj.someList[0].a

//
callSomeOtherApiWithId(id)

[Emil Kantis]

Personally I often use rest-assured for testing APIs. You can do body-assertions and extractions with it. They have a Kotlin DSL module

[Emil Kantis]

your example could look like

val id = When {
  get("/api/v1/hello")
} Then {
  body("id", equalTo("someId"))
  body("someList[0].a" equalTo("foo"))
} Extract {
  body().jsonPath().getString("id")
}

println(id) // > someId