public static String makeTestDataDirectory(final Class<?> clazz, final String... childPath) {
        return Storage.toPath(makeTestDataPath(clazz, childPath));
    }
Creates a {@link File} reference that .  For example, calling this method with "a", "b", and "c" as the
{@code childPath} arguments would yield a relative directory like: {@code test-case-data/clazz/a/b/c}. It is
a good idea to use the test class for the {@code clazz} argument so that it's easy to find the data if
necessary after test execution.

@return UNIX-formatted path to a directory in the underlying {@link Storage}. The directory is relative to the
supplied class in the {@code /target} directory. Each {@code childPath} passed introduces a new sub-directory
and all are placed below the {@link #TEST_DATA_RELATIVE_DIR}
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/util/TestSupport.java