Spock - test fails after interaction testing - spock

Question

This test works only when condition is tested. When mixed with interaction testing, it fails.
class Test extends Specification {
class Inner {
public String greet() {
return "hello"
}
}
def "simple test"() {
given:
def inner = Mock(Inner)
inner.greet() >> { "hi" }
when:
def msg = inner.greet()
then:
1 * inner.greet() // Below will pass when this line commented out.
msg == "hi"
}
}
The test will pass when interaction testing is removed.
Condition not satisfied:
msg == "hi"
| |
| false
null

Answer 1

It should be:
#Grab('org.spockframework:spock-core:0.7-groovy-2.0')
#Grab('cglib:cglib-nodep:3.1')
import spock.lang.*
class Test extends Specification {
class Inner {
public String greet() {
return "hello"
}
}
def "simple test"() {
given:
def inner = Mock(Inner)
when:
def msg = inner.greet()
then:
1 * inner.greet() >> "hi"
msg == "hi"
}
}

Answer 2

Let's talk a bit about what's going on. (Or if you don't want to, read the "Scope of Interactions" section.)
What's happening is an issue of scoping. As you may know, you can have multiple sequential when/then pairs; any Mocking done in a then block is actually scoped to only its when block. What happens if the Mocked method was already defined outside the when/then scoping? The Mock defined in the then block takes precedence.
Congratulations! You've stumbled across the only way to overwrite established Mocked values/methods. I spent a long time figuring out how this worked before the new documentation was released.
So we know you're overwriting your mock that defines a value to return. How do we proceed from here?
given:
def inner = Mock(Inner)
1 * inner.greet() >> message
expect:
"hi" = inner.greet()
where:
message = "hi"
Parting thought... I hope you're not testing a value that you set within your test. That's effectively asserting 1 == 1. If you want to test your actual code while testing behavior I'd suggest using a Spy
given:
def inner = Spy(Inner)
1 * inner.greet() >> {
callRealMethod() // Actual method, read the documentation I linked
}
expect:
"hi" = inner.greet()