Validation of parameter passed to mock call in Spock

If you use Spock, sometimes you want to check mock method call. You can of course do it like this:

	def "Should pass expected parameter to method"() {
	given:
	Service service = Mock()
	def person = new Person("Paweł", "Stawicki")
	when:
	service.method(person)
	then:
	1 * service.method({
	it.firstname == "Peter" && it.surname == "Stawicki"
	})
	}

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Problem here is that when the parameter passed to the method is wrong, you won't know what is wrong with it:

Too few invocations for:

1 * service.method({
            it.firstname == "Peter" && it.surname == "Stawicki"
        })   (0 invocations)

Unmatched invocations (ordered by similarity):

1 * service.method(eu.vegasoft.spocktest.validateparam.Person@40f892a4)

Sometimes we want to validate also parameter passed to the mock method. We can do it like this:

	def "Should pass expected parameter method and validate it"() {
	given:
	Service service = Mock()
	def person = new Person("Paweł", "Stawicki")
	when:
	service.method(person)
	then:
	1 * service.method(_) >> {Person p ->
	assert p.firstname == "Peter"
	assert p.surname == "Stawicki"
	}
	}

view raw gistfile1.groovy hosted with ❤ by GitHub

Now when the passed parameter does not match, we can see exactly what was wrong with it:

Condition not satisfied:

p.firstname == "Peter"
| |         |
| Paweł     false
|           3 differences (40% similarity)
|           P(aw)e(ł)
|           P(et)e(r)
eu.vegasoft.spocktest.validateparam.Person@34b23d12