Boolean getter methods prefixed by `is` are not properly mocked

[piotrminkina]

Describe the bug

In Groovy, it is possible to declare a getter method for a returned Boolean value, where the prefix get can be replaced by is. A subsequent reference to such a method in shorthand notation works correctly in both cases, but Spock cannot correctly mock such a method when the shorthand notation is used.

To Reproduce

Consider the following example specification:

class SimpleSpecification extends Specification {
    def 'test stub assertions'(VcsDetails vcsDetails) {
        expect:
        verifyAll(vcsDetails) {
            lastTag == 'current-tag'
            cleanTag == true
            isCleanTag == true
        }

        where:
        vcsDetails << [
            Stub(VcsDetails) {
                lastTag >> 'current-tag'
                cleanTag >> true // condition will be NOT satisfied
                isCleanTag >> true
            },
            Stub(VcsDetails) {
                lastTag >> 'current-tag'
                isCleanTag() >> true // condition will be satisfied
                isCleanTag >> true
            },
        ]
    }

    static interface VcsDetails {
        String getLastTag()
        Boolean isCleanTag()
        Boolean getIsCleanTag()
    }
}

Expected behavior

Spock will correctly mock the isCleanTag() method using shorthand.

Actual behavior

Spock does not mock the isCleanTag() method using a shorthand. The example specification posted ends with an error only for the first test case, where shorthand is used.

test stub assertions [vcsDetails: Mock for type 'VcsDetails', #0]
Condition not satisfied:

cleanTag == true
|        |
false    false

	at com.example.SimpleSpecification.test stub assertions_closure1(SimpleSpecification.groovy:10)
	at app//groovy.lang.Closure.call(Closure.java:412)
	at app//spock.lang.Specification.verifyAll(Specification.java:276)
	at com.example.SimpleSpecification.test stub assertions(SimpleSpecification.groovy:8)

Java version

openjdk 11.0.26 2025-01-21
OpenJDK Runtime Environment Temurin-11.0.26+4 (build 11.0.26+4)
OpenJDK 64-Bit Server VM Temurin-11.0.26+4 (build 11.0.26+4, mixed mode)

Buildtool version

---

Gradle 8.2.1

Build time: 2023-07-10 12:12:35 UTC
Revision: a38ec64d3c4612da9083cc506a1ccb212afeecaa

Kotlin: 1.8.20
Groovy: 3.0.17
Ant: Apache Ant(TM) version 1.10.13 compiled on January 4 2023
JVM: 11.0.26 (Eclipse Adoptium 11.0.26+4)
OS: Linux 6.13.6-200.fc41.x86_64 amd64

What operating system are you using

Linux

Dependencies

+--- org.spockframework:spock-core:2.3-groovy-3.0
| +--- org.junit:junit-bom:5.9.0
| | +--- org.junit.platform:junit-platform-engine:1.9.0 (c)
| | +--- org.junit.platform:junit-platform-launcher:1.9.0 (c)
| | --- org.junit.platform:junit-platform-commons:1.9.0 (c)
| +--- org.junit.platform:junit-platform-engine -> 1.9.0
| | +--- org.junit:junit-bom:5.9.0 ()
| | +--- org.opentest4j:opentest4j:1.2.0
| | --- org.junit.platform:junit-platform-commons:1.9.0
| | --- org.junit:junit-bom:5.9.0 ()
| --- org.hamcrest:hamcrest:2.2
+--- net.bytebuddy:byte-buddy:[1.14.0,1.15.0) -> 1.14.19
--- org.objenesis:objenesis:[3.4,3.5) -> 3.4

Additional context

No response