testing - How to prepare a nested data structure for a data-driven test in Karate?

Question

I currently use junit5, wiremock and restassured for my integration tests. Karate looks very promising, yet I am struggling with the setup of data-driven tests a bit as I need to prepare a nested data structures which, in the current setup, looks like the following:

abstract class StationRequests(val stations: Collection<String>): ArgumentsProvider {
    override fun provideArguments(context: ExtensionContext): java.util.stream.Stream<out Arguments>{
        val now = LocalDateTime.now()
        val samples = mutableListOf<Arguments>()

        stations.forEach { station ->
            Subscription.values().forEach { subscription ->
                listOf(
                    *Device.values(),
                    null 
                ).forEach { device ->
                    Stream.Protocol.values().forEach { protocol ->
                        listOf(
                            null,
                            now.minusMinutes(5),
                            now.minusHours(2),
                            now.minusDays(1)
                        ).forEach { startTime ->
                            samples.add(
                                Arguments.of(
                                    subscription, device, station, protocol, startTime
                                )
                            )
                        }
                    }
                }
            }
        }
        return java.util.stream.Stream.of(*samples.toTypedArray())
    }
}

Is there any preferred way how to setup such nested data structures with karate? I initially thought about defining 5 different arrays with sample values for subscription, device, station, protocol and startTime and to combine and merge them into a single array which would be used in the Examples: section.

I did not succeed so far though and I am wondering if there is a better way to prepare such nested data driven tests?

Answer 1

I don't recommend nesting unless absolutely necessary. You may be able to "flatten" your permutations into a single table, something like this: https://github.com/intuit/karate/issues/661#issue-402624580

That said, look out for the alternate option to Examples: which just might work for your case: https://github.com/intuit/karate#data-driven-features

Here's a simple example:

Feature:

Scenario:
* def data = [{ rows: [{a: 1},{a: 2}] }, { rows: [{a: 3},{a: 4}] }]
* call read('called.feature@one') data

and this is: called.feature:

@ignore
Feature:

@one
Scenario:
* print 'one:', __loop
* call read('called.feature@two') rows

@two
Scenario:
* print 'two:', __loop
* print 'value of a:', a

This is how it looks like in the new HTML report (which is in 0.9.6.RC2 and may need more fine tuning) and it shows off how Karate can support "nesting" even in the report, which Cucumber cannot do. Maybe you can provide feedback and let us know if it is ready for release :)