Karate test framework: retry until complex condition on arrays [duplicate] - cucumber

Question

I'm using Karate framework with JUnit.
Using this feature:
Given path 'save_token'
And request
"""
{
"token": "test_token"
}
"""
And retry until response.tokens ==
"""
[
"test_token"
]
"""
When method POST
I'm having this exception:
java.lang.ArrayIndexOutOfBoundsException: 1
at com.intuit.karate.core.MethodMatch.convertArgs(MethodMatch.java:60)
at com.intuit.karate.core.Engine.executeStep(Engine.java:141)
at com.intuit.karate.core.ScenarioExecutionUnit.execute(ScenarioExecutionUnit.java:171)
When response.tokens list is empty:
{
"tokens": []
}
I don't understand why == does not work in this case (it should return false, and keep retrying).
Thanks in advance!

Answer 1

The retry until expression has to be pure JavaScript and the special Karate match keywords such as contains are not supported, and you can't do a "deep equals" like how you are trying, as that also is not possible in JS.
EDIT: in 0.9.6. onwards you can do a complex match in JS: https://stackoverflow.com/a/50350442/143475
Also note that JsonPath is not supported, which means * or .. cannot appear in the expression.
So if your response is { "tokens": [ "value1" ] }, you can do this:
And retry until response.tokens.includes('value1')
Or:
And retry until response.tokens[0] == 'value1'
To experiment, you can try expressions like this:
* def response = { "tokens": [ "value1" ] }
* assert response.tokens.includes('value1')
At run time, you can use JS to take care of conditions when the response is not yet ready while polling:
And retry until response.tokens && response.tokens.length
EDIT: actually a more elegant way to do the above is shown below, because karate.get() gracefully handles a JS or JsonPath evaluation failure and returns null:
And retry until karate.get('response.tokens.length')
Or if you are dealing with XML, you can use the karate.xmlPath() API:
And retry until karate.xmlPath(response, '//result') == 5
And if you really want to use the power of Karate's match syntax, you can use the JS API:
And retry until karate.match(response, { tokens: '##[_ > 0]' }).pass
Note that if you have more complex logic, you can always wrap it into a re-usable function:
* def isValid = function(x){ return karate.match(x, { tokens: '##[_ > 0]' }).pass }
# ...
And retry until isValid(response)
Finally if none of the above works, you can always switch to a custom polling routine: polling.feature
EDIT: also see this answer for an example of how to use karate.filter() instead of JsonPath: https://stackoverflow.com/a/60537602/143475
EDIT: in version 0.9.6 onwards, Karate can do a match in JS, which can simplify some of the above: https://stackoverflow.com/a/50350442/143475