def resource = new AccessorBackedExternalResource(name, resourceAccessor, resourceUploader, resourceLister, true)

        when:
        expectResourceRead(name, "12345")
        def result = resource.writeToIfPresent(file)

        then:
        result.bytesRead == 5
        file.text == "12345"
        0 * _

        when:
        expectResourceRead(name, "hi")
        result = resource.writeTo(file)

        def outFile = tmpDir.file("out")
        file.text = "1234"

        expect:
        def resource = new LocalFileStandInExternalResource(file, TestFiles.fileSystem())
        def result = resource.writeToIfPresent(outFile)
        result.bytesRead == 4
        outFile.text == "1234"

        file.setText("abc")
        def result2 = resource.writeTo(outFile)
        result2.bytesRead == 3