private static void assertLayerSize(int expected, String imageReference)
      throws IOException, InterruptedException {
    Command command =
        new Command("docker", "inspect", "-f", "{{join .RootFS.Layers \",\"}}", imageReference);
    String layers = command.run().trim();
    Assert.assertEquals(expected, Splitter.on(",").splitToList(layers).size());
  }
Lists the files in the {@code resourcePath} resources directory and builds a {@link
FileEntriesLayer} from those files.
jib-core/src/integration-test/java/com/google/cloud/tools/jib/api/ContainerizerIntegrationTest.java