given:
        def extraSource = file("src/main/${app.sourceType}/extra.${app.sourceExtension}")
        extraSource << sourceFile.text.replaceAll("main", "main2")

        outputs.snapshot { run "mainExecutable" }

        and:
        objectFileFor(extraSource).assertExists()

        when:
        extraSource.delete()

        and:
        run "mainExecutable"