Spock data driven testing with classes to test for "instanceof" assertions

Question

I have a test where I want to test a specific result to be of a kind of a class. Asserting this with the instanceof keyword. Sadly I did not figured out how to actually provide a data value expectedClass in the data table without having a Problem to actually call it with instanceof. I think the keyword instanceof is the issue here because it only accepts class/interface names. Any idea how I can test what I want to test in another way?

class BattleResolverFactoryTest extends Specification {

    def uut = new BattleResolverFactory()

    @Unroll
    def "should return proper BattleResolver for given ConflictType"(Conflict.ConflictType conflictType, Class<? extends BattleResolver> expectedInstance) {
        when:
        def battleResolver = BattleResolverFactory.getResolver(conflictType)
        then:
        battleResolver instanceof expectedClass
        where:
        conflictType                            | expectedClass
        Conflict.ConflictType.INFANTRY_CONFLICT | TestInfantryResolver
        Conflict.ConflictType.ARMOR_CONFLICT    | TestArmorResolver

    }
}

Answer 1

You can use isCase like so:

class BattleResolverFactoryTest extends Specification {

    def uut = new BattleResolverFactory()

    @Unroll
    def "should return proper BattleResolver for given ConflictType"(Conflict.ConflictType conflictType, Class<? extends BattleResolver> expectedInstance) {
        when:
        def battleResolver = BattleResolverFactory.getResolver(conflictType)

        then:
        expectedClass.isCase(battleResolver)

        where:
        conflictType                            | expectedClass
        Conflict.ConflictType.INFANTRY_CONFLICT | TestInfantryResolver
        Conflict.ConflictType.ARMOR_CONFLICT    | TestArmorResolver

    }
}

Answer 2

As tim_yates said you can use the groovy function isCase or the java function isAssignableFrom, or you could use the groovy in keyword (which delegates to isCase).

• expectedClass.isCase(battleResolver)
• expectedClass.isAssignableFrom(battleResolver)
• expectedClass in battleResolver