How to inject Groovy closure variable into Spock mock predicate argument? - groovy

Question

I found an interesting line in Spock interactions documentation:
http://spockframework.org/spock/docs/1.3/interaction_based_testing.html#_argument_constraints
last line of constraints, example with closure predicate:
1 * subscriber.receive({ it.size() > 3 && it.contains('a') })
My question is: is there a way in Groovy to pass this predicate as variable?
My testing environment code:
class Something {
Doer doer
Something(Doer doer) {
this.doer = doer
}
boolean doSth(x) {
if (!doer.validate(x)) throw new RuntimeException()
true
}
}
class Doer {
boolean validate(int x) {
x == 2
}
}
and test code:
def "some test"() {
given:
def d = Mock(Doer)
def s = new Something(d)
when:
s.doSth(2)
then:
1 * d.validate({ it == 2 }) >> true
}
what I would like to achieve:
def "some test"() {
given:
def d = Mock(Doer)
def s = new Something(d)
def myClosureVar = { ??? }
when:
s.doSth(2)
then:
1 * d.validate(myClosureVar) >> true
}

Answer 1

The closure takes an argument, as indicated by it having a defined value. That value is the corresponding method parameter. So whatever closure you define outside of your interaction, you need to make sure that the interaction hands over that parameter to the closure, i.e. you need to create your own (small and simple) closure evaluating the outer (potentially lengthier, more complex) closure with the parameter it:
1 * d.validate({ myClosureVar(it) }) >> true
Sorry for the repetition, but I always prefer a full MCVE in my answers so you can easily copy, paste, compile and run:
Application classes:
package de.scrum_master.stackoverflow.q60341734
class Doer {
boolean validate(int x) {
x == 2
}
}
package de.scrum_master.stackoverflow.q60341734
class Something {
Doer doer
Something(Doer doer) {
this.doer = doer
}
boolean doSth(x) {
if (!doer.validate(x)) throw new RuntimeException()
true
}
}
Spock specification:
package de.scrum_master.stackoverflow.q60341734
import org.junit.Rule
import org.junit.rules.TestName
import spock.lang.Specification
class SomethingTest extends Specification {
#Rule
TestName testName
def "some test"() {
given:
def d = Mock(Doer)
def s = new Something(d)
when:
s.doSth(2)
then:
1 * d.validate({ println "$testName.methodName: closure parameter = $it"; it == 2 }) >> true
}
def "another test"() {
given:
def d = Mock(Doer)
def s = new Something(d)
def myClosureVar = { println "$testName.methodName: closure parameter = $it"; it == 2 }
when:
s.doSth(2)
then:
1 * d.validate({ myClosureVar(it) }) >> true
}
}
Console log:
some test: closure parameter = 2
another test: closure parameter = 2