default public Graph openTestGraph(final Configuration config) {
        return GraphFactory.open(config);
    }
Creates a new {@link Graph} instance from the {@code Configuration} object using {@link GraphFactory}.
The assumption here is that the {@code Configuration} has been created by one of the
{@link #newGraphConfiguration(String, Class, String, LoadGraphWith.GraphData)} methods and has therefore
already been modified by the implementation as necessary for {@link Graph} creation.
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/GraphProvider.java