file('a/build.gradle') << """
ext.foo = "Moo!!!"
"""
        file('a/child/build.gradle') << """
task printExt {
    doLast {
        println "The Foo says " + foo
    }
}
"""
        when:
        run(":a:child:printExt")

        then:
        outputContains("The Foo says Moo!!!")
    }