when:
        createRunner().withTestKitDir(null)

        then:
        def t = thrown(IllegalArgumentException)
        t.message == 'testKitDir argument cannot be null'
    }

    def "can set custom test kit directory"() {
        given:
        def testKitDir = testDirectoryProvider.createDir('some/dir')

        when:
        def runner = createRunner()
            .withProjectDir(workingDir)